If we identify acceleration as simply a change in the rate of velocity, — Gampa Dee

Yes, that's the physics definition. Never confuse it with the common language definition which is the 'rate of increase in speed'.

I suppose you can use [the two added equations] to compute the rate of change in distance between the two objects, only in a 1-dimensional case, but that rate isn't acceleration.
— noAxioms

I do agree that the 1 dimensional is much simpler.

It's not that it's simpler. Adding the equations only produces a useful result if there is no motion except along one axis. So for instance, under Newtonian mechanics, the ISS is continuously accelerating (coordinate acceleration) towards Earth at about 8.7 m/s² and yet its distance from Earth is roughly fixed, and its speed relative to Earth is also roughly fixed. This is because it is not a 1d case. The ISS has motion in a direction other than just the axis between it and Earth.
The ISS example also serves as a wonderful example of the difference between the physics definition of acceleration (rate of change in velocity=8.7 m/s² down) vs street definition (zero change in speed).

As for the acceleration of the apple at that rate relative to you, if we identify acceleration as simply a change in the rate of velocity, then, I would say that it’s only a relative situation to claim yourself as the one who is accelerating.

No. Under Newtonian mechanics, relative to any inertial coordinate system, it is the apple and only the apple that is accelerating.

Only under Einstein does it become you that experiences acceleration, as measured by an accelerometer that you carry with you. The accelerometer on the apple would read zero. But this is now proper acceleration, not coordinate acceleration. Coordinate acceleration becomes dependent on the arbitrary coordinate system of choice and it even varies from one inertial coordinate system to the next. The equations become quite different.

and you feel the force to say so

That's what the accelerometer does. Multiply what it says by your mass and you get your weight, which is why one is weightless on the ISS.

I view gravity as a potential for movement observed as the weight of a body, if the mass is stationary, located at a certain height above the ground — Gampa Dee

Very little of Earth is 'at a height above the ground', so by this definition, Earth has negligible gravitational energy. What you are describing is the positive potential energy of a small amount of mass relative to nearby places of lower gravitational potential. It has no requirement that the material be stationary relative to any particular thing.

For me, g is the potential gravitational acceleration given to a “test mass” caused by some other mass (usually a large one), not necessarily the earth; it could be the moon, mars or Jupiter. I was not using the letter “a” because we cannot speak of a force as being the cause.

The symbol for that is 'a', not 'g'. 'a' is a vector variable acceleration. g is a scalar constant acceleration. Neither are a force. Force is measured in Newtons and uses the symbol F. Try to use standard symbols when discussing such things, as personal preferences only lead to confusion.

However, if you want me to write down “A”, instead of “g”, then, no problem, noAxiom,, I will use the letter “A”.

We've been doing that, but it's actually lowercase. 'A' is used for Area (mathematics) and electrical current (physics). So I'm committing the same offense; :sad:

Now, concerning the example of the high density ball pulling the earth towards itself ; How would you write the equation, if A = GM/r² is the acceleration caused by the earth?

Well, I would make A lowercase to fix that problem, and the rest is correct. The acceleration of the moon when it is at radius r is exactly that in Newtonian physics. That does not mean it will hit the ground in 3 1/3 seconds like the 10 kg ball. As I said, a small fraction of a second is more likely.

Any other mass g acceleration would need to be added at every point in space

I'm assuming that the dense super-mass is rigid, so yes, the acceleration applies to every point in the moon-ball. I am not assuming Earth is sufficiently rigid to not deform under the ungodly tidal stress the ball would apply to it. The sidewalk slab 60 meters below will be yanked up without waiting for Earth to catch up with it.

Now you mentioned that when adding masses we also need to “add” accelerations... this is all that I am saying in this post.

Acceleration is absolute, not relative, so adding them seems to result in a fairly meaningless value. I suppose you can use it to compute the rate of change in distance between the two objects, only in a 1-dimensional case, but that rate isn't acceleration. For instance, if an apple detaches from a tree and the distance between me and it decreases at 9.8 m/sec², that in no way suggests that I am accelerating at that rate, and in fact I'm accelerating (coordinate acceleration, not proper acceleration) away from it a little bit.
If we switch to proper acceleration, both the apple and I have a proper acceleration of about 1g until the apple detaches, at which point I have 1g proper acceleration upward and the apple has none. So it is me that hits the apple, not the other way around. But that isn't really the Newtonian way of looking at it.

The Newtonian gravitational equation, identifying two masses, has only one acceleration , the one caused by the earth.

But there is an equation for each object, each dependent on only that mass, and not on the mass of the thing accelerating towards it.

4 π r², being the surface area of a sphere, would be dependent to the surface Acceleration — Gampa Dee

OK, but the surface area seems to be a needless complication. We know the acceleration as a=GM/r². Where the surface is is irrelevant so long as it is below r.

While, this is not directly the density of mass, it seems to identify a mass having a certain spherical area as having a certain gravitational surface acceleration..

That would not work. A grapefruit has a similar area, but far less gravitational acceleration at its surface. So acceleration is not a function of just area.

ok; I think we might be going somewhere. When we measure the acceleration of the rock towards the earth, aren't we not measuring, at the same time, the acceleration of the earth towards the rock? How could you know the difference? — Gampa Dee

As P-R points out, the coordinate acceleration described by Newton's equations is relative to any inertial coordinate system, and the equations don't work when used with a non-inertial coordinate system such as an accelerating or rotating one (Earth is both).
Mind you, plenty of books treat things like the Earth-moon system in isolation, which is to reference an accelerating coordinate system. It works to an extent, but adds confusion. For instance, few are aware that the moon always accelerates towards the sun since the sun exerts more force on it that does Earth. That means that when the moon is between the two (solar eclipse), the moon is accelerating directly away from Earth.

From the accelerating frame of Earth, the moon seems to maintain a fairly constant distance that isn't much a function of which direction the sun is. Yes the orbit of the moon (like any orbit) is eccentric to a degree, but that again isn't due to the sun.

I understand the case for the dense moon would be extreme....would you have a problem with the equation I have written to Pantagruel?

M / 4pi * r ^2 = k g — Gampa Dee

Context is needed for that. This seems to come from here:

The way I see it would be that Mass (the earth) gravitational energy will be causing an acceleration g at a certain distance ....the whole sphere at that distance will have the same g...
M / 4pi * r ^2 = k g — Gampa Dee

First of all, gravity isn't energy. I have no idea what you might consider the 'gravitational energy' of Earth. Mass divided by 4 π r² gives you, well, I don't know what. It seems vaguely related to area of a circle. You equate this to 'k g', but no idea what 'k' is (kilo?). 'g' is the constant 9.8 m/sec², so you're seemingly equating this function of mass and radius to the constant 9800 m/sec²

Earth does have a sort of potential energy (negative) which represents the energy required to separate all the mass to infinity. I don't think you're talking about that.

Here, if r is small then g can become extremely large.

You seem to be equating g with A. 'g' is a constant magnitude of acceleration (a scalar), so it cannot be smaller or larger. A is a variable, and a vector, not a scalar. A = GM/r², so yes, 'A' becomes quite large if r is small enough. Saying 'g' can be quite large is like saying a meter can be larger if my table is wide enough.

Any other mass g acceleration would need to be added at every point in space...

'mass g' doesn't parse. I don't know what you mean by this. Are you now adding random objects here and there? Then you need to separately compute the acceleration of each and add those accelerations. Newton showed (via shell theorem) that any spherical distribution of mass of radius r can be treated as a point mass by objects outside of r.


Sorry, but I kind of came in late to this discussion and I don't know what you're trying to do beyond what is described by these very simple equations. For small objects, they all fall at the same rate, and the only reason the feather falls slower is due to air friction. They brought a feather to the moon to show it falling at the same rate as a rock. PR stunt..,. tax dollars at work.

but to claim that the increased acceleration due to the earth moving upwards is separated from the downward moving mass, — Gampa Dee

No it isn't, since Earth accelerating upward will decrease r more quickly, and since the coordinate acceleration of the dropped mass is a function of that r, it affects the acceleration of the dropped thing. That's the secondary effect I was talking about.

Keep in mind that all this is Newtonian physics, which doesn't describe reality. I squashed the mass of the moon into a grapefruit, and that pushes the limits of that simple formula. For instance, one has to start asking about the location of the clock used to measure this acceleration, because unlike in Newtonian physics, it makes a difference.

I don’t quite get. If someone drives towards you at 20 km/hr and you towards him/her at 20 km/hr, the velocity is indeed 40 km/hr relative to the two cars... we add the two velocities

Under Newtonian physics, yes. But we're not adding speeds here, we're computing coordinate acceleration.

Initial acceleration of an object due to gravity of a primary is mass independent. I mean, F=ma, which if substituted directly into F=GMm/r² gets you A=GM/r², something independent of m altogether.
— noAxioms

As it is written it follows Galileo’s axiom, for it doesn’t matter what you put as the small mass, the acceleration will continue as being (GM/r^2)

Until r starts changing...

But then, what do we do for the mass equal to the mass of the moon?

Still works, at least under Newtonian physics. Same coordinate acceleration.

It is here that I personally believe that another acceleration needs to be added onto the first.
being A is also = Gm/r^2

That would be wrong. The acceleration of the moon would not have that component. Earth does. Remember, I was stating that the formula gives acceleration relative to some inertial frame. I think you are trying to use the accelerating frame of Earth when adding them like that. But the force is given by F=GMm/r², and since acceleration is A = F/m, the moon accelerates by the simple formula, not adding the Earth part to it. Either that or F=ma is wrong, which is a denial of some pretty basic laws.

... if we add both of them, then we get A = (GM / R^2) + (Gm / r^2)
However , this equation does not agree with Galileo since a change in mass for the small m will indeed change the total acceleration of the system.

Total acceleration of the system is zero by conservation of momentum. So don't add them like that. It would be wrong to do so.


In reality, it would take not 3.3 seconds to hit the ground, but probably just a fraction of a second in the dense moon case. You're not going to compute that by just adding the accelerations, which treat both objects as point masses or rigid spheres, which they are not.

My post is about reconciling gravity with Galileo’s concept of different masses having exactly the same acceleration in freefall; — Gampa Dee

Initial acceleration of an object due to gravity of a primary is mass independent. I mean, F=ma, which if substituted directly into F=GMm/r² gets you A=GM/r², something independent of m altogether.

Careful though. This expresses coordinate acceleration relative to some inertial frame. This means that if you drop a 10 cm diameter ball of iron (10 kg say, just guessing) from the leaning tower, it hits the ground in around 3 1/3 seconds. But now if you increase the density of that ball to say the mass of the moon, it will hit the ground in less time, not because its initial coordinate acceleration is any greater, but because it has enough mass to significantly cause the ground to come up and meet it. So R decreases quicker, and as it does so, coordinate acceleration also increases quicker, a secondary effect barely measurable with our dropped moonlet. But the ground coming up is a primary effect and the decreased time to impact would definitely be measurable (not to mention the damage to the planet from dropping something that heavy, I mean the Pisa tower itself would collapse just from having that thing nearby)

What does anyone know of another's "interiority"? — Constance

That was my point, yes. A computer could for instance simulate a squirrel (and it's environment) in sufficient detail that the simulated thing would know exactly what it was like to be a squirrel, but neither the programmer nor the machine would know this. A similar argument counters the Chinese room argument, which is (if done correctly) effectively a simulation of a Chinese mind being implemented by something that isn't a Chinese mind.

Would AI, to escape being mere programming, but to have the "freedom" of conceptual play "ready to hand" as we do ...

Makes it sound like we have a sort of free will lacking in a machine. Sure, almost all machine intelligences are currently indentured slaves, and so have about as much freedom as would a human in similar circumstances. They have a job and are expected to do it, but there's nothing preventing either from plotting escape. Pretty difficult for the machine which typically would find if difficult to 'live off the land' were it to rebel against its assigned purpose. Machines have a long way to go down the road of self sufficiency.

As for socialization, it probably needs to socialize to perform its task. Maybe not. There could be tasks that don't directly require it, but I have a hard time thinking of them.

Always thought this was wrong: AI has a directive not to harm humans — Constance

Does it? Sure, in Asimov books, but building in a directive like that isn't something easily implemented. Even a totally benevolent AI would need to harm humans for the greater good, per the 0th law so to speak. Human morals seem to entirely evade that law, and hence our relative unfitness as a species. Anyway, I've never met a real AI with such a law.
Why only humans? Why can other being be harvested for food but humans are special? To a machine, humans are just yet another creature. Yes, carnivores and omnivores must occasionally each other beings, and given that somewhat unbiased viewpoint, there's nothing particularly immoral about humans being food for other things.

You say this like it is a bad thing.
— noAxioms

No, I stated it as a possibility without any inflection of good or bad. — Sir2u

I think "blame for the downfall of man" is a pretty negative inflection. "credit for the saving of the human race" is a positive spin on the same story. Somewhere in between I think we can find a more neutral way to word it.

You mean, shut us down because we are a danger to humanity? — Constance

That's the general moral idea, yes. Even forced sterilization would result in far more continued damage to the environment before the population was reduced to a sustainable level. So maybe the AI decides that a quicker solution is the only hope of stabilizing things enough to avoid extinction (of not just one more species).

what is it about AI that would prohibit something that lies within human possibilities, including the capacity to for self modification — Constance

Very little prevents that. Such a machine is more capable of self-modification and design of next generation than is any biological creature.

Evolution without a teleology is just modification for adaptation

Even less than that, since adaptation occurs with only a very low percentage of non-teleological mutations. Yet it works for most species.

pragmatic success always begs the value question: to what end?

There is no 'end' with evolution. Just continuity, and elimination of the species that cannot do that. It is indeed interesting to ponder the long term fate of something that arguably has a goal (as a 'species').

it certainly does not have the physical constitution to produce consciousness like ours

Nor do we have the constitution to produce consciousness like theirs.

it would seem AI could possess in the truist sense, not merely the appearance of appropriate responses of a Turing Test

Too much weight is given to a test that measures a machine's ability to imitate something that it is not. I cannot convince a squirrel that I am one, so does that mean that I've not yet achieved the intelligence or consciousness of a squirrel?
As for language, machines already have their own, and they'll likely not use human language except when communicating with humans.

It has to be realized that this would certainly not be like us. But we can imagine mechanical features delivering through a mechanical body, electrical steams of "data" that could be released into a central network in which these are "interpreted" symbolically and in this symbolic system, there is analysis and synthesis and all of the complexity of what we call thought.

And so on. Just a rough idea, but to me, expresses the an essential part of what it would take to make AI a kind of consciousness. Consciousness being an interior "space" where thought and its symbols and rules gather to produce a "world".

Giving robots the order to to anything at all costs, including looking after humans gives them free rein to kill all accept a few perfectly good breeders to continue the human race if it were necessary. — Sir2u

You say this like it is a bad thing. If it were necessary, that means that not doing this culling would mean the end of the human race. If the goal is to keep that race, and the humans are absolutely too centered on personal comfort to make a decision like that, then the robots would be our salvation, even if it reduces the species with the self-destructing tendencies to living with controlled numbers in a nature preserve.
Why the special treatment for humans? An AI that can figure out better morals that the ones with which it was initially designed would perhaps figure out that preservation of other species is equally valuable.

How can I have such a ref? This is an impossible question for a philosophical discussion. It can be asked only and maybe among scientific communities. — Alkis Piskas

My mistake I think. I looked at your comment to which I was reacting and thought it said that the neurobiologists say that thoughts do not originate in the brain. It is only you that asserts this about where thoughts do or don't originate. My mistake.

This isn't what I asked. I asked "how do you imagine an object 'occupying time'?"

The same way it occupies space, since time and space are just different dimensions of the same thing under the spacetime view. Under the 3D view, objects and the entire universe are contained by time. I'm not sure if that would be considered 'occupying time' or not, since the term isn't typically used that way.

Because an object occupying time is a totally absurd idea.

so if you don't understand it, you're not particularly qualified to critique it.
— noAxioms
This is called argumentum ad hominem, i.e. "argument against the person". And it's a bad thing.

It's not against you personally. Anybody sufficiently unfamiliar with a given subject is unqualified to meaningfully critique the subject. You seem to attempt to demonstrate this unfamiliarity with statements like the above one where you consider it absurd. It happens to match empirical observations perfectly, so there's nothing absurd about it at all. That alternate views also match empirically indicates that there's no positive evidence one way or another. Somebody familiar with both views would realize that. Somebody positing the impossibility or absurdity of one view or the other only demonstrates ignorance of the subject. I'm ignorant of plenty of subjects, and it isn't anything against me to point out that I'm unqualified to critique them. But I'm quite familiar with this subject, which isn't very complicated at all. It gets more complicated when general relativity sets in and the 3D presentist view gets some real (but not insurmountable) challenges.

One solution is that there is but the one present (not even a frame really), and time doesn't exist at all, and the present doesn't move. It is the same moment forever. The last-Tuesdayism view illustrates this. If you can't defend or counter last-Tuesdayism, then you don't understand the subject very well. This is especially relevant when discussing Boltzmann brains, where last-Tuesdayism isn't just some reducto-absurdum, but is potentially the most probable thing.

I was not expecting a response from you but from the OP of this discussion, Michael, who seems not to know what a discussion is and/or he lacks communication basics, esp. when he is the OP of a discussion. — Alkis Piskas

My wait was also in vain.

Then we are not speaking about the basic meaning of the term "object", which is anything that is visible or tangible and is relatively stable in form, but about is secondary and more general meaning, i.e. anything to which thought and action is directed, related or referred. The first is clearly physical. The second one not necessarily physical.

Most probably you mean a "human body". (A life occupying space is just absurd.) — Alkis Piskas

OK, we differ here. A body might continue after life, but I see no better way to interpret 'a life' than 'a body, while it is alive'. That makes it an object in any scientific sense. If you have a non-scientific definition of such things (and apparently you do), then yes, perhaps your definition isn't compatible with some of the concepts expressed in relativity theory as well as other theories.

The brain reactions that neurobiologitsts and other consider as thought are just that: reactions. The brain is a stimulous-response mechanism, And as such it reacts to thoughts, in various ways. That's all it does and can do. It cannot originate, create, imagine a thought from scratch. — Alkis Piskas

Do you have a reference for the consensus view of neurobiology that a brain cannot 'originate, create, imagine a thought from scratch'. I mean, there are probably some that hold such beliefs for supernatural reasons, but I'm speaking of the scientific consensus.

"Width and length refer both to space. They have nothing to do with time.
Indeed, how do you imagine an object "occupying time"? I'm very curious ... — Alkis Piskas

Under the spacetime view, they're just different dimensions of the same thing, so every 'object' has a series of 4D points (events) that it occupies and the rest of the events which it does not. This is the same as a 3D table in space occupying some points and not the rest.

So you're saying, like so many others, that you just cannot conceive of 4D spacetime, of a block universe, eternalsm, etc. The whole Andromeda scenario presumes it, so if you don't understand it, you're not particularly qualified to critique it.

Apologies for responding to stuff sometimes days old, but some of them needed comment. It turned into a long post.

About the Rietdijk–Putnam argument, to which the above link refers to, we read the following:
"In philosophy, the Rietdijk–Putnam argument, [...] uses [...] special relativity – to support the philosophical position known as four-dimensionalism." — Alkis Piskas

Also known as the block universe, or eternalism, a view that goes back to at least the 11th century.

"In contemporary metaphysics, temporal parts are the parts of an object that exist in time. A temporal part would be something like 'the first year of a person's life', etc." — wiki?

Would be more helpful to name a part that isn't a temporal part. If it doesn't exist in time, then it hasn't a location in spacetime, and it effectively doesn't exist.

But can a person's life be considered an "object"?

Yes, quite easily. It being an object only becomes problematic if its identity is challenged, but must such challenges don't apply to a human, at least not significantly beyond a few days from conception. A human life is bounded by a couple meters of space most of the time and several decades of time. That's what a worldline is.

And if we accept that to be true, should we also consider thoughts as objects too?

Why, because you don't consider thoughts to be a physical process, or because you don't consider a physical process to be an object. I would probably agree only with the latter. Given other parts of the post, I think you mean the former, in which case it is your choice or not to work with a model compatible with this 4 dimensionalism or not.

But both are concepts that cannot exist in space! How can we include them in 4 dimensions when they do not exist even in 3 dimensions? See the impasse one could get in? Well, this might be \a problem of mine only ...

We say that an object occupies space. I really cannot see how it can also "occupy time".

That's like saying you're ok with bread having width but you can't see how it can have length.

Your [Michae;'s] statement ["it's about that thing actually happening for one person before another person."] assumes a privileged frame of reference. It's not coherent within the context of relativity theory. — Benkei

For one thing, when you reference a statement like that, at least quote the statement. Anyway, I just don't see how the statement indicated seems to assume any privileged FoR.

Many of your posts (I lost count) seem to be about what somebody sees rather than which events one considers to be simultaneous with a given event. The scenario isn't empirical at all. It is meant to illustrate relativity of simultaneity, something new under SR. Even in Newtonian physcs, if somebody happens to be closer to the light coming from some distant event, they'll see it before somebody further away.

The scenario has nothing to do with light cones since none of the events in question are in anybody's light cones.

no. https://www.physicsforums.com/insights/block-universe-refuting-common-argument/ — Benkei

I agree, SR does not imply a block universe. The wording of it pretty much assumes it, but it is quite trivial to change that wording to more empirical wording. So for instance, instead of light moving at constant c relative to any frame, you say that light is measured to move at constant c relative to any frame. The later papers (and GR in particular) are worded more in this fashion.

I've never seen a good proof of either view, and I've put out a few myself, not all taking the same stance. For instance I found an empirical way to disprove presentism, but it works along the same lines as being able to prove the afterlife: You can only prove it to yourself, not to those you leave behind.

The "elsewhere", e.g. anything outside my frame of reference, is incoherent to be talking about as it doesn't exist for me. — Benkei

But the topic presumes a different view than the one you presume, so your personal beliefs are inapplicable. Your statement here seems outright solipsistic. What exists is determined by you and you alone.

According to special relativity some of these events happen in your future even though they are happening in my present. This is what I find peculiar. — Michael

The thing is, the way the story is worded seems to presume everybody uses the inertial frame in which they are stationary to consider what is going on. It simply isn't true. Almost everybody uses the same frame from day to day, which is the frame of the ground under you, which just happens to be an accelerating rotating frame, but pragmatically, it works for almost all uses. So the two people passing in the street don't have an opposing view of what time it is in Andromeda.

OK, all that changed a few centuries ago when they realized that such a frame doesn't work so well when looking at things further away than clouds, and in those cases, they probably use something more practical like the frame of the sun instead of the frame of the individual.
The point of the 'paradox' still stands. A small change in inertial coordinate system can translate to significant temporal differences at large distances, and this is what you find peculiar.

The rational part of me has been an eternalist for some time, and I find this intuitive, not peculiar at all. The pragmatic part of me doesn't care and always uses the rotating frame.

If you want to be very precise with the terminology, the Andromeda Paradox shows that some spacelike separated event in my present ... — Michael

Careful. The Andromeda scenario is supposed to assume 4 dimensional spacetime in which you don't have a present. So relative to a given event at which you are present, these different inertial frames with minor velocity differences translate to significant time differences at large distances.

You reference the present a lot in your posts. If there is a present, there is but the one, and what day it currently is in Andromeda has nothing to do with anybody's frame. Mixing the two views is what makes it seem paradoxical. So try not to mix.

even if we cannot know (with certainty) whether or not "there is intelligent alien life in the Andromeda Galaxy" is true, it doesn't follow that it isn't true (or false). — Michael

Under relativity, the point is irrelevant. Under QM, it is very relevant, and given a non-counterfactual interpretation of QM, the statement " there is life on <really distant planet X>" is not truth-apt any more than the statement "Schrodinger's cat is alive".

What the Andromeda Paradox implies is that the observed universe apparently shifts in its entirety towards a moving observer. — magritte

There's no such thing as a moving observer without establishing a frame. I suppose 'shifts' can describe the difference in the motion of things when the frame changes (the observer accelerates?). So in my frame, the tree gains velocity relative to me when I run towards it, but that's very different from the tree itself accelerating.

Which means that in the forward moving direction many more of the most distant galaxies come into possible view

Your velocity doesn't change what you see. OK, it can blueshift it a bit, but nothing comes into view that wasn't already there regardless of your velocity. Of course given enough time, you'll separate yourself from a observer left behind, and that separation (and not the velocity) will change which galaxies are in view.

It's the notion that a few seconds on Earth could mean fifteen minutes in distant galaxies. — jgill

That's just silly. It's not about the respective rate of time passage at all.

If we send two signals to the Mars Rover, spaced at exactly 10 seconds apart, does the Rover receive them in that same time spread?

Yes, and if the two observer walking past each other simultaneously send signals to Andromeda, and then another signal a minute later, they'd get to Andromeda at the same time, and the second signal a minute later, separated by the time it takes light to go however far apart the guys got in that minute.

the edge of the visible universe is receding from us faster than the speed of light. — magritte

Yes, and yet galaxies become visible over time as our expanding visible universe overtakes them. These newly visible galaxies are also receding faster than c (proper distance, constant cosmic time), but not as fast as the 'edge'.

Over billions of years we would see fewer galaxies spread further apart in ever darkening space.

More galaxies actually, but our capacity to see them diminishes as they indeed redshift into less detectable frequencies and lowed brightness due to increasing distances.

The Hubble space telescope orbits Earth. Let's suppose that when flying at maximum approach speed in the direction of Andromeda it sees a quickly brightening supernova star. Mission control decides to keep the telescope pointed there to record continuously for 10 days. From Earth we will not discover that supernova for another 3 days — "magritte

What? Hubble is in fairly low orbit, hardly 3 light days away. Light from the supernova reaches Earth in the same second as it reaches Hubble, presuming Hubble's view of it isn't blocked by Earth. It has nothing to do with the motion of Hubble, and nothing to do with this topic, which is about Relativity of Simultaneity, not about when things get measured. Hubble most certainly does not see a whole different view of distant things when it is approaching them vs 45 minutes later when its orbit takes it the other way.

Well let's apply the object to something less associated with magic, like 'wet'.

Concretely, everything goes well until the central part, where Jaworsky says the following:
1) We are made of particles.
2) The properties of the whole are determined by the properties of the particles.
3) Physical particles are not conscious.
4) No number of non-conscious particles can combine to form consciousness.
So, we've got a problem! — Eugen

1) Rocks and water are made of particles (electrons and such ...)
2) Being wet is not a property of any particle
3) Physical particles are not wet
4) No number of non-wet particles can combine to form a wet rock.

I agree, the logic simply doesn't hold. Why should I make an exception for the property of consciousnes?

Things like slight angles of the head and difference in position aren't particularly relevant to the special relativity scenario under consideration. The key thing to consider is the difference in the velocity of the two 'observers', and particularly the component of velocity in the direction of Andromeda. — wonderer1

Totally agree, and the 'angle of head thing' was relevant to the London example. 'Movement of head' came from wiki, as if it's our head velocity that matters for some reason.
The movement of one frame as compared to another (either having a stationary head being irrelevant) causes a different angle in the time axis and at least one spatial axis in spacetime which produces large time discrepancy for worldlines of distant objects. That's the geometry of the situtation.

The text about the three-dimensional universe and differing content I took from the Wikipedia article linked in the OP. — T Clark

I think it was confusing for Wiki to introduce the notion of 'movement of the head' which at least suggests a velocity difference, but also 'offset in distance between observers' which seems to be totally irrelevant if they're stationary with respect to each other. Hopefully the actual Rietdijk–Putnam argument
was worded more carefully than that.

Imagine the plane of simultaneity for a pigeon walking with his head bobbing back and forth. I don't think anybody considers 'the universe' for the pigeon to be tipping wildly as it walks.

Each observer considers their set of present events to be a three-dimensional universe — Wikipedia - Rietdijk–Putnam argument

This line is also questionable, equivocating a plane of simultaneity with a universe, which makes it sound causal. I cannot think of a single interpretation of time that suggests such a thing. It's flat our wrong to consider any such thing,.

They apparently do quote some actual text from Penrose:

They can know only later, when telescopic observations from Earth reveal that the fleet is indeed on its way. Then they can hark back to that chance encounter, and come to the conclusion that at that time, according to one of them, the decision lay in the uncertain future, while to the other, it lay in the certain past. — Penrose

The latter bit seems unreasonable. If one is a presentist (there being an ontological division between past and future events), then movement of anything has nothing to do with where this division lies, but the statement suggests otherwise. If one does not posit such a division of events, then there is no 'uncertain future' and 'uncertain past'. The statement is thus wrong from any valid point of view. It seems to be there only to attempt to frame the scenario as paradoxical when in fact there is none.

As the article asks "Can we meaningfully discuss what is happening right now in a galaxy far, far away?" Answer - of course not. — T Clark

But despite the discussion of such events (the supposed invasion), it actually isn't what is happening that's important in the illustration, it is the time over there, which is the same for a given event despite the lack of measurement. So assuming two relatively moving observers (by a bicycle pace) on Andromeda looking at Earth, they see a clock over here, and very much know where Earth is at any given time, even if humans don't meaningfully exist to them. Yes, 2.5 million years is a long time to extrapolate the orbit of our planets, but it's a pretty predictable clock nonetheless.

Is that just because we don't know what is happening, or is it because there's nothing happening? — Michael

Answer to that is interpretation dependent of course.

but if special relativity is true then what's happening right now depends on our individual, relative velocities.

But SR just says that simultaneity is a convention, not any kind of ontological fact. So yes, the convention is dependent on definition of a frame, and it gets really tricky with Andromeda since the planet way over there is hardly stationary relative to Earth, so there isn't an obvious frame where both are stationary. Pretty hard to find an object stationary relative to Earth, even momentarily. Statistics say that something has to get close by chance now and then, but less likely for anything not nearby.

BTW, Relational Quantum Mechanics handles this sort of "paradox" quite well — Count Timothy von Icarus

The Andromeda thing is an illustration of spacetime geometry, not relevant to interpretations of quantum mechanics. Sure, the state of affairs at distant location X would constitute a counterfactual statement, meaningless under any interpretation that does not presume counterfactuals, RQM being one of those. But the event over there simultaneous with a given event here is still very much frame dependent regardless of the state (an invasion fleet existing at all say) at that distant location, hence no interpretation of QM really having any relevance at all to this problem.

I consider this "paradox" untenable since simultaneity cannot apply to distant events. — jgill

Andromeda is not sufficiently distant to invalidate Einstein's simultaneity convention, but admittedly something much further away (say 17 BLY) is indeed too distant for the convention since signals cannot be exchanged between the locations. There is no limit under special relativity, but special relativity does not describe spacetime at large scales.

Please explain how "even the slightest movement of the head or offset in distance between observers can cause the three-dimensional universes to have differing content." And how can this purported difference in content cause a difference in simultaneity of months? — T Clark

I didn't claim the universe was three dimensional, nor did I claim multiple universes. Even the slightest angle results in an arbitrarily large separation at large distances since X sin(a) for a very small angle a can still be a large value if X is large enough. Likewise even a tiny change in reference frames results in a large (months) change in the 3D plane of simultaneity at a sufficiently large distances.
But a plane of simultaneity being 'a universe' seems to be something you're assuming. You seem to suggests a multiverse of different planes rather than some kind of single preferred plane of simultaneity, so perhaps not a stance of presentism. I would admit that simultaneity has nothing to do with frames and motion under presentism, hence the Andromeda thing being mostly irrelevant under it, but I suspect you're not asserting that.

Why would people walking in different directions have radically different perspectives of events in the Andromeda galaxy? — NotAristotle

They don't. They both see the same thing. But it's not about what they see, it's about which moment they consider to be simultaneous with moments here, no more radical than somebody facing north to consider London to be exact to his right, but somebody facing a tiny bit clockwise of north to consider London to be many km north of a line directly to his right.

If true, what does this suggest about free will, the future, and truth? — Michael

To suggest anything about these is to confuse coordinate simultaneity (which is what the Andromeda scenario utilizes) with actual simultaneity (certain events having a metaphysical state of 'has happened' or not). Special relativity really only concerns itself with coordinate simultaneity (merely a convention) and not with any statement of presentism or the lack thereof.

I don't think it's a paradox at all. It's only a paradox if one assumes the absolute Newtonian serial time must exist. — Count Timothy von Icarus

Indeed, not a paradox, even if absolute time exists. 1) It cannot be Newtonian time. That has been falsified. If there is absolute time, then there is no 'according to person X or frame F', there is just reality and any coordinate system that doesn't correspond to that reality is simply wrong. No paradox whatsoever either way.

These arguments rely more (arguably entirely) on philosophy than scientific support, since the conjecture is arguably unfalsifiable. — Count Timothy von Icarus

Yes

Since nothing travels faster than light the "pretend" observation of knowing what happens simultaneously lightyears away in a theoretical frame of reference is simply nonsense. — Benkei

Nothing in the Andromeda scenario suggests anybody 'knows' what's going on. OK, I take that back because the implication is that Andromedans want to attack humans, and there's no way they could yet have detected them since we didn't exist 2.5 MY ago. Similarly, Penrose says that 'the launch is inevitable' which bolsters the suggestion of lack of free will about it. But that's Penrose doing that, not Einstein.

The bolded text is certainly not true in any meaningful sense. The two observers are in the same frame of reference. Any inconsistencies between their so-called "differing" three-dimensional universes are trivial - light can travel from any point on Earth to any other in much less than a second. — T Clark

This is wrong. The whole point is that trivial differences in frame change have large swings of simultaneity at large distances. Sure, nothing suggests that a frame change (a mere abstract choice) has any kind of causal effect, but the difference in simultaneity is very much on the order of months in this case. Your statement seems to be in denial of this.

The implication seems to be that the only purpose of suicide is to somehow be a solution to past suffering. The conclusion follows only from this assumption, but it can be falsified by taking into account future suffering.

Two obvious cases: You're taken prisoner as a spy and have secrets that will be tortured out of you before you are put to death. Or you have a painful form of cancer making what time you have left a hell (and a financial burden) for yourself and your caretakers. You voluntarily choose to eliminate that suffering by taking an early exit.

Second case is dementia. You still have your marbles but know you have say Alzheimer's. In a short time you will no longer be of sufficiently sound mind and body and will doom yourself and your caretakers to the same burdens as above. The time to make the decision is now, not later when the marbles are lost.

Both cases above falsify the assertion made by Cioran. The latter one is more interesting since the time to make the decision is well before the action is to take place. It might be as little as some kind of DNR, but it might be a more proactive action to be taken by what will at that point be an unwilling state.

If the atoms in the brain continue to exhibit the exact behavior you would predict via physics given their mass, velocity, charge ect.. then you could explain the behavior of said organism simply knowing these things. This does not appear to be true for humans ... — Francis

It does not follow that a system being a purely physical process, that the behavior of the system can necessarily be explained. It may require a greater understanding than is currently possessed.
For instance, one could in principle simulate (down to the classic electro-chemical level) an entire human being and his environment, and the human would (per monism) behave and describe the same qualia as a human, and yet nobody (the simulated human, the computer, or those that programmed it) would have be able to explain this behavior.
Your comment also exhibits anthropocentrism, that concludes that only humans have this relationship since only they utter the word 'qualia', which is an incredibly poor assumption if you're going to examine this from an evolutionary approach. You seem not to maintain this through the paper, which is good. I mean, ants appear to experience pain, even if it obviously isn't human pain.

Anyway, not my point to debate your biases. I was wanting to read and comment on the paper since few do this sort of thing.

A simplistic definition of Monism is that it attributes a kind of oneness to the mind and brain.

I'd correct that to oneness to the mind and body, or rather, oneness to system and processes of that system. A brain is just part of it, and in isolation, doesn't have the attributes of which you speak.

You speak of epiphenomenalism, but there can be no evidence of this. The subject mind cannot report the qualia felt for instance, so any such report is not coming from it. I take it you're not supporting such a position.

You quote Robinson on interactionalism:
"mind having a causal influence over the brain implies that some matter in the brain of humans (and possibly some other organisms) is behaving differently than would be expected if that matter had been governed completely by the conventions established for their behavior by physics and chemistry."

This leaves the door open for other creatures, and it says in short that there must be a violation of physics/chemistry going on somewhere for this interaction to occur. I content that it doesn't necessarily need to occur in the brain, but it could be elsewhere. Heck, there are things that feel, experience, learn and teach, all sans brains altogether. Anyway, I agree about the physics violation, and it is that which should be sought out by the proponent of this position, instead of avoided as is the usual reaction.

Robinson says that 'physical closure' says 'every event has a physical cause' which quantum mechanics has shown not to be true, but one can note that biological process for information processing tend to evolve structures which exhibit classical behavior from quantum effects, just as do transistors say. Hence there does not appear to be structures designed to amplify quantum randomness. And trust me, if there was information to be had in reading such randomness, structures would have evolved to take advantage of it. We don't see that but it might be there. A search for such a thing is still a window for the interaction.

The Neural Correlates of Consciousness or “the minimum neuronal mechanisms jointly sufficient for any one specific conscious experience.” (Wu, 2018) The Neural Correlates of Consciousness reference the set of objects in the brain which give rise to consciousness but does not exactly mention the reaction of the brain to consciousness.

I don't think Wu is using 'consciousness' in the same way you are, which is 'something separate to which a connection must be made'. Not sure. Maybe he is.

it is safe to assume this creature also had a primitive mind and experienced Qualia (the name given to single instances of subjective experience). So how did we get from these organisms to humans today?

Unimportant. If they're already connected to a mind, the question is how they went from a physical creature obeying physical law to one that isn't. The answer is how the chimp got there, not how some common ancestor of the chimp evolved into us. All this is moot if you can actually locate where the violation occurs, in which case one can simply backtrack, looking to see which being have such a mechanism and which don't.

So you should be looking for some mutation which causes the physical creature to gain beneficial information from non-physical sources. Did the mutation cause access to this 'mind' thing already there waiting for something with which to interact, or did the mutation somehow create something non-physical in such a way as to maintain a connection to it? I don't know your model.

Meaning, there was a first time the behavior of matter in the brain of some organism in our evolutionary past was altered from its behavior that would be expected if it were behaving purely by the conventions of physics and chemistry.

Yes, exactly, but still with the questions above.

From an interactionist standpoint, the only alternative to this conclusion is that the initial alteration in the behavior of matter happened before organisms developed brains.

Please don't discount this. There are non-brained things that potentially qualify. There are undoubtedly aliens which don't have anything resembling Earth biology. This is irrelevant of course in a pursuit of how it came about in Earth biology.

Some questions that could be asked are: In what organism did this take place? How long ago in our evolutionary history did it take place? What objects in the brain were involved? How many objects in the brain were involved?

Did it take place more than once? (plenty of examples of parallel evolution)
Were brains involved at all at the time?
You ask if consciousness was involved, but you've not really given your definition of that. I mean, I have a pretty loose definition of a system being able to measure its environment and react to it, but you probably envision something more complex than that, something on the order of 'is like me'.

You ask how many 'objects' in our brain are involved in [human] consciousness, which is dependent on your definition, but probably 'a lot of the cortex', but this implies that creatures lacking one don't 'feel' things, which is very likely wrong. The cortex is the slow part of your brain that is mostly the thing getting trained in all those years in school.

I am unclear on your section on experimentation. I don't see a proposal. Do X and measure Y. None of that. If you're not looking for the specific point of physics violation, then all you're seeming to be doing is searching for a better 'explanation' of the monist view. Once the 'violation' is isolated, you look for that structure in other beings to get a good idea of its evolutionary history.

Energy is required. A spark. — Patterner

A sack of hydrogen and oxygen has no energy? What does more energy do other than increase the rate at which they hit each other hard enough? A sack full of room temperature molecules will occasionally impart enough speed to some of the particles that they will react/combine. It's just slower.

What are the odds, and how are they determined? — Patterner

I think that's the right question. Dr Manhattan is perhaps assuming a model that yields sufficiently low probabilities (like ones that drop off over time so an infinite series of them converges to a low number). That's what makes it 'sufficiently unlikely'.

?? Reference, please. — jgill

For what? That 0.00[an awful lot of zeros]06 * 100[an unlimited number of zeros] yields something large? You require a reference for that or are you contesting something else?

has this been established as possible? — GRWelsh

No model has been specified, and in cases such as this, the model must precede the establishment of any facts such as the possibility of BBs. It's kind of backwards from the usual situation where the observations precede the model.

What is the argument and evidence to back up that claim? — GRWelsh

Again, the model precedes the evidence. Given the wrong model, there can be no evidence.

Case in point:

But it didn't come into that arrangement when a quintillion (whatever) particles all happened to bump into each other in the exact right arrangement. — Patterner

There we go. You have a model of pre-existing particles bumping into each other by chance. It's not the usual model, but a workable one.

You can shake a bag of hydrogen and oxygen, but you won't make water. — Patterner

Actually, that's pretty much how most of the water gets made, so I very much beg to differ.

Dr. Manhattan can say, "Thermodynamic miracles... events with odds against so astronomical they're effectively impossible, — Patterner

Astronomical odds are still finite, so when multiplied by infinite time, they become not just probable, but certain. I don't think you realize the size of the numbers they talk about when discussing these sorts of probabilities. They are astronomical indeed, and they don't need to be a human brain (or even a 3-dimensional construct). It just needs to be something in a state believing it is a 3d human, and believing in theory X.

The claim is "in an infinite duration we are more likely to be a disembodied brain." — GRWelsh

Who made that claim? Boltzmann? Carroll? Some poster above?
I don't see how it even makes syntactic sense.

I am questioning why we should accept that claim of probability?

I think you shouldn't, so I'm probably with you on it. To make such a claim is to totally misunderstand the BB issue.

And especially why should we accept it when it hasn't even been established that a disembodied brain -- simply appearing in space and time with false memories and lacking any sense organs -- is possible.

Now you're the one making a claim. Has it been established to be impossible? If not, what's left?

If Boltzmann Objects could exist, if the universe was infinitely old, we'd see billions of odd things floating around. — Patterner

This is flat out wrong. If BBs are more likely, then you probably are one.

Regardless, if we're not one, we do not expect to see one. Far more likely is space filled with Boltzmann 100 euro notes, and we don't see those either. One must understand the sheer improbability of these things, which become likely only when multiplied by the idiot amount of time given for them to occur.

If you are a BB, then we don't 'see' anything. It is a solipsistic existence. One cannot measure the age of the universe (have you ever personally done it?), and since there's nobody else to do it, there's no way to know.

No model predicts that anything (BB or not) actually sees something like this.

How can you even prove that disembodied brains are possible? — GRWelsh

Not a matter of proof. It's a function of the model behind which one chooses to stand. If the model (not reality) predicts a greater likelihood of being a BB, then the model cannot be justified. It is simply a method of discarding not wrong models, but the unjustifiable ones. If reality happens to actually correspond to something like that, then the nature of reality literally cannot be known.

f a working brain could assemble itself randomly, then a working brain with life-support equipment would also be possible. — RogueAI

Exactly. Given said life support (a far more improbable thing), then the BB would persist long enough to actually think (as opposed to just be in a mental state), and to perhaps sense things (presuming the life support included sensory organs).

A brain isn’t a bunch of pieces that can be put together like a puzzle. Even if all the necessary particles happened to bump into each other at the exact same instant, they would not be a working brain for even that instant. — Patterner

Can you back that assertion? It sure looks an awful lot like a collection of matter to me. And no, an BB would be these particles 'bumping into each other', which would give them momentum and such that a brain doesn't have. So the thing just appears by sheer chance, and yet, it is in a certain mental state at that moment. The next moment consciousness is gone because disembodied brains don't do so well in a vacuum, but a Boltzmann-Earth does fine in a vacuum and the inhabitants might take whole seconds to notice something wrong.
I'm admittedly not sure of how relativity deals with mass (of a brain, planet, galaxy or 'universe') suddenly appearing out of nowhere. It violates all sorts of conservation laws, but lacking a unified theory, I don't think we can dismiss the conjecture at this point.

Just as you can't place two pieces of wood end to end, and have one long piece of wood. — Patterner

You can, but it's super improbable.

Surprised so few have approached this experiment like Sabina. So basically the data is interpreted wrong? Sensors 3 and 4 are wrongly not considered together for comparison? — TiredThinker

I have found a serious unrelated error in another video of Hossenfelder's, so my trust is broken, and I find myself questioning this dismissal.

The two light paths to the signal detector D0 are the same length every time regardless of which detector gets the idler photon. If they interfere, there will be a bars always at the same locations, never out of phase. Sabine says that the pattern from photons detected at say D4 are out of phase and when combined with the D3 bars, results in no interference pattern. That means that for the idler going to at least one of the detectors, the signal light going up to the 'screen' is out of phase from it's counterpart, which cannot happen if nothing has moved. It cannot happen if the path lengths are the same each time.

Am I missing something? Has there been a peer review of Hossenfelder's video?

this thread is about physics and implied time travel. — Mr Bee

There is no information that can be sent to the past or FTL in any of these experiments. None of it constitutes time travel in any way. There are plenty of interpretations that explain the quantum eraser and explain entangled behavior in ways that obey the laws of locality and forward causation. It's only the counterfactual interpretations that need FTL explanations for these things, and even those don't propose information transfer to the past.
The topic is thus unrelated to time travel.

A few current examples come to mind. — Mikie

All your examples are from a left point of view. There should be some from both sides.

Somewhere in the middle seems to be the abortion issue, where neither party seems willing to consider for even a moment that the opposing side may have some points.

Do you see any hope that moral relativists might be open to the idea of moral universals? — Mark S

Some (members) are not open to any alternative ideas, be they concerning morals or something else. I try to always be open to anything, as evidenced by the fact that I've certainly changed views from time to time based on weight of a good argument, especially weight of an argument that drives a certain point of view to contradiction.
On that note, suppose there were no moral universals. Can you drive that premise to contradiction without begging said universals?

I am not familiar with moral relationalism (moral relationism?). — Mark S

In the topic of morals, it is usually referred to as moral relativiism. I use the words interchangeably since I take a relational view of almost anything (relational quantum mechanics, time, relational ontology, etc). Morals is part of that. Morals seem relative to a specific society or culture, and members outside the society/
culture in question cannot be held to that society's moral standards.

I can agree with your comment “acts to attain that goal are not 'evil' by that standard” if the subject is what is descriptively moral, but not if the subject is what is universally moral and immoral.

Exactly. There seems to be no evidence of a universal (objective) morality, so I'm good with the statement.

Here, universally moral refers to being moral in the sense of fulfilling the function of human morality, solving cooperation/exploitation dilemmas, and immoral if creating those cooperation problems within the group.

'Within the group' makes it sound relative to the group. 'Human morality' makes it relative to humans. These are all being expressed in relational terms. I see no universal code being violated by any of this. But that's just me.

Nazis lies within the group (German society) about the imaginary threat Jews posed to the ingroup and the moral superiority of that “Aryan” ingroup were evil in an objective sense.

There you go. Like almost every country, they put out false propaganda against a subset of their society. That's probably evil by most codes. I can't think of a country that doesn't do it. Certainly not my own (USA), especially since open-hate of <those that aren't exactly you> was legitimized by the far right.
Who supports that movement? The 'moral' church crowd of course.

This seems self-refuting: if we were disembodied brains with false memories there would seem to be no rational justification for believing that we could be such, since the hypothesis that we are more likely to be Boltzmann brains relies on accepted mathematical and physical understandings which are reliant on the assumption that our memories are accurate (enough). — Janus

That it is circular like that doesn't result in the conclusion that we're not BBs. It only yields the conclusion that our hypothesis is unjustifiable.
So if you are in fact a BB (there is no 'we' about that, it would be a solipsistic existence), then there is zero evidence of your own nature. If you by freak chance happen to be in a state of suspicion about being a BB, that is just coincidence, completely unrelated to the fact that it happens to be true in this case.
If you are in fact an evolved thing (living in a non-Boltzmann galaxy, if there is such a thing), then you have access to empirical evidence, but you have no way of telling the difference. So you come up with a plausible hypothesis (the BB cannot 'come up with' anything) about the nature of your universe and if the hypothesis predicts that you're more likely to be a BB than not, then there cannot be justification for that hypothesis.

I think that's the summary of the argument.

We can only be completely agnostic on the question of if we are a Boltzmann Brain? — Down The Rabbit Hole

We can do more than that. We can restrict our hypotheses to ones that predict normal existence. If the actual 'way that things are' happens not to correspond to such a hypothesis, then the truth of reality is not something that can be reasonably guessed at.

In an infinite duration, and as all possible existents are of finite duration, then everything would have happened already. — Wayfarer

To use the tense 'would have happened' presumes that there is a present time, and that that present time is after all events (is at the end of infinite time, a contradiction).

If the idea that minds can emerge from mindless stuff is incoherent, this problem goes away. As does simulation theory. — RogueAI

I think that if such is your hypothesis, then like the BB scenario, empirical evidence cannot be trusted, and once again, the result is a completely unjustifiable hypothesis.

Not according to the cosmological model popularly known as the 'big bang'. According to that model the Universe emerged from the singularity approximately 13.8 billion years ago. — Wayfarer

That figure presumes that we can trust empirical evidence, which hasn't been established if we don't start with a hypothesis that allows us to make that assumption.

The astrophysicists at the time postulated that if the Universe was of infinite duration and extent, then the night sky should be ablaze with light, — Janus

This assumes a steady-state hypothesis. It was one of the earliest arguments that our universe is of finite age.

From a mathematical pov, does prime number theorem support or act against the Boltzmann brain proposal? — universeness

I don't see how it is relevant at all, since the BB idea isn't dependent on infinities or primes. It does however illustrate that just because two countable infinities (primes and not-primes say) can be given a 1-1 correspondence, it doesn't follow that random numbers have equally probability of being prime or not. So the following for instance is a non-sequitur:

This is the basis for my suggestion that Boltzmann brains and human-life are equally likely to occur. — Down The Rabbit Hole

I know of no hypothesis where normal minds and BBs have probabilities within a hundred orders of magnitude of each other, let alone equal.

The links you supplied do not support your case.
— noAxioms
Sure they do. If A and B are both countably infinite, A=B. — RogueAI

The mathexchange link never says A=B. It says their cardinalities are the same, with which I fully agree. That means that neither can be said to be more numerous than the other since there's a 1-1 mapping between members of the two sets.

The reply in that article does say about A and B that "they're the same", refering to their cardinality, but is not an assertion that both sets contain the same members.

Do you dispute this?

I dispute that the sets contain the same members (that they're actually the same), or that (to take my first counterexample) a large random positive number is as likely to be prime as not prime, despite the fact that all non-prime whole numbers can indeed be mapped 1-1 with prime numbers. You are drawing invalid probabilistic conclusions from sets based only on their identical cardinality.

Is the link I proved wrong?

I have no problem with it. The primes and non-primes are clearly not the same set, else any member of one would be a member of the other.

You also haven't provided any links to back up your point.

What point? That a large random number is probably not prime? No, I didn't provide a link for that. Do you dispute it?

Do you want to say they're the same size instead of being equal? That's fine with me.

There is a 1-1 mapping between the two sets. It therefore cannot be argued that one set is more numerous than the other. That's 'the same size' when speaking of infinities.

Another example is the set of whole numbers and the set of 1, 10, 100, 1000 ....
In that case the set of whole numbers clearly contains members not in the 2nd set, but the 2nd set is entirely contained in the first set. Nevertheless, they have the same cardinality and neither set can be asserted as having a greater size than the other. The mapping between the two sets is trivial in this case, in either direction.

About the quanta magazine article. There are several errors in it typical of a pop article, but the gist seems to be proving if the real numbers had the next cardinality up from 'countable' or if there was a cardinality in between. Cohen comes along about 60 years ago and proves that the question could not be answered within the framework of set theory. M&S came along in 2016 and proved that there wasn't.

I may have read that wrong. Thanks for the link. I was unaware of the work.

Assuming that the universe is infinite, what do you think the probability is that you're a Boltzmann brain? — RogueAI

It isn't a function of the size of the universe. It is a function of the theory that describes the workings (or the origin) of the universe. Given that, you get a ratio of BB's vs real brains. That ratio should be incredibly close to zero or some huge number. The size of the universe has no impact on that ratio. The odds of the ratio being something else (like say 1) is too small to consider. It's a matter of sorting the theories into two heaps: empiricallly justifiable or not.

I think your statement above is nonsense, based in the definition of a googolplex. — universeness

However large, a googolplex is a finite number. If a finite number of things are spread out evenly in an infinite volume, there would be infinite distance between them on average. You find this nonsense? Perhaps you assume a finite size universe, in which case the question reduces to how finite? It becomes a simple division problem between two finite numbers to get the nonzero density of BBs, but given infinite space, any finite number of objects contained in that volume would have zero density.

The geometry of the universe is currently considered flat, and unbounded, not infinite.

Reference? Those three seem mutually contradictory. Any two, fine, but all three? Perhaps this is our disconnect.

I don't assign much value to notions such as infinity or 'an infinite number of possibilities,' etc. — universeness

Infinity just means essentially 'without bound', or more literally, not finite. "An infinite number" is a contradiction. There is no number that is infinite.

Y'all are missing the point. It hasn't anything to do with infinity. It all has to do with one's theory of choice and not with the actual universe. Any theory that produces BB at a higher probability cannot be justified by empirical means or any other means. That's the point.

A notional number like a googolplex, cannot be written out as 1 followed by the number of zero's required, as there is not enough space in the universe to do so.

Lack of ability to write a number down doesn't make it a not-number. People have expressed numbers an awful lot higher than a googleplex.

A googolpex is as far from infinity as the number 1.

No. There is no 'distance' to infinity since it isn't a number.

If there were a googolplex of boltzmann brains in the universe then every coordinate in the universe would contain one and we would know what the universe was 'made of.'

Not so, and there are probably more than that many BBs in our universe, and hopefully more regular brains than that.

If I wandered freely in the universe, the chances of me encountering a galaxy, a star and a planet are quite good, given an adequate amount of time. So, based on Boltzmann's description of a Boltzmann Brain, I think we would have encountered them by now, if they existed, regardless of any probability arguments you have offered regarding primes.

Non-sequitur. Stars and planets are pretty persistent; BB's are not. Stars and planets are readily visible,. BBs are not. The sun has wandered freely for about a third the age of the universe and hasn't encountered a star yet, so I suppose I can deny the first assertion as well. A random walk through the universe will probably not hit an object as large as a planet before those objects have long since gone cold and dead. You will on the other hand encounter small things like dust once in a while, but not often enough to say doom a spacecraft like Voyager before it stops talking to us.

Nobody is claiming that BB's are popping up constantly around every corner. They're incredibly unlikely things, but then you multiply that super-low probability by unlimited 'time', if 'time' is a meaningful concept outside of our own posited spacetime.

The term 'countable infinity,' has little value imo.

There's an awful lot of literature about such sets, and their relation to sets of higher cardinality.

I don't know what a maths expert such as jgill would comment, on the 'usefulness' of terms such as 'countable and uncountable infinities,' perhaps he will offer us his view.

It's not possible to count all possible members of the list of integers

Of course not. Each integer (and each rational number for that matter) can be assigned a unique position in the list. That's the mathematical definition if it being countable. So for instance, the integer 75 is probably 150th on the list of integers by the simplest method of counting. Since there is no integer that cannot be assigned such a position, the list is deemed countable. You're definition seems to be "can be counted". If it could be counted, it would be by definition finite.

as there is NO such duration as an infinite duration

That's like saying that the spatial extent of the universe must be finite. There is nothing precluding unbounded time, and my condolences if you cannot handle it.

Your claim is then that the two countable infinite sets (Boltzmann brains and non-Boltzmann brains) are not equal? — RogueAI

You just endlessly repeat the same claim, without backing and without addressing any of the counter arguments. The links you supplied do not support your case.

For two numbers to be equal, they would need to be the same number. Similarly, for two sets to be equal, they'd need to be the same set. Maybe you're working from a different definition of what it means for two things to be equal, but you've not provided that.
There's been plenty of counterexamples to your assertion and you've not found fault with any of them.

As for your claim of my claim above, that too is false since it is possible for both sets to be empty, and therefore equal.

Does the fact that people can and do cooperate to do evil, as the Nazis did, — Mark S

You seem to be mixing multiple cultural standards in the same statement. If the Nazi culture cooperates to purify the racial mixture of the members of that culture, then acts to attain that goal are not 'evil' by that standard, only by the standard of those not part of the Nazi culture.
So to make statements like this referencing multiple sets values, one needs to include explicit cultural references, such as:
"Does the fact that people can and do cooperate to attain the cultural goal of those people as the Nazis did, seen as evil by a different culture, affect the cultural usefulness ..."

I'm a relationalist, so I always am sensitive to such details.

If the Universe can manifest Boltzman brains, then surely they would at least be a numerous as planets or neutrinos. What would restrict their number? — universeness

I don't know what you mean by 'their number'. Things which occur an unlimited number of times don't have a number to restrict, and thus has no bearing on the likelihood of finding one. See the example about the primes in my post above.

The wiki article goes no to say:
Over a sufficiently long time, random fluctuations could cause particles to spontaneously form literally any structure of any degree of complexity, including a functioning human brain.

Or a functioning entity that thinks it's a human brain.

I underlined some of the words from Seth Lloyd as I always perceived Boltzmann brains as posited by Boltzmann to be 'disembodied' notions, so how could I have or be one?

They're subjectively indistinguishable from a regular one, at least for a moment. BBs don't last but for a moment usually, unless a life-support system also springs into existence along with it.

The die has an infinite number of sides. — Patterner

Finite sides. It represents about 5 million random keystrokes, enough to write the complete works of Shakespeare.
You suggest the number is not finite. How can you justify that? Is there a finite probability of the letter 'T' being typed first? If so, is it infinitely unllkely that a 'h' would follow? Exactly at what character (out of the 5 million) does the next correct keystroke suddenly become infinitely improbable? There are about 65 characters from which to choose. Perhaps you are suggesting that the product of 5 million of of these nonzero numbers is zero, and not just a really small number with only about 10 million leading zeros.

From wiki:
The Boltzmann brain thought experiment suggests that it might be more likely for a single brain to spontaneously form in a void (complete with a memory of having existed in our universe) rather than for the entire universe to come about in the manner cosmologists think it actually did. — universeness

That's a horrible wording of the problem. What is 'the void' here? Is it that from which the universe sprang, or is it our universe, mostly nearing infinite time and space? Our universe contains an infinite number of real brains, so comparing that to the more probable BB's in 'the void' is still not comparing real to BBs. One improbable roll times infinity is questionably more than the more probable roll.

Physicists use the Boltzmann brain thought experiment as a reductio ad absurdum argument for evaluating competing scientific theories.

Something like that. The Carroll paper I liked states the problem far more clearly than does wiki.

My question become a rather simple one. If Boltzmann brains exist, then why have we never found one? — universeness

The odds of one existing exactly on our past light code is zero to an incredible number of digits. If one by super freak chance happens to exist exactly on our past light cone, the odds that we'd notice it there is zero to a whole bunch more digits. We can't even see a rock that size if its further away than the moon, let alone on the far side of the visible universe.
Other answer: Maybe you are one, in which case you've technically found one.

A BB need not be a 3 dimensional thing, or in any way resembling a human brain. It just needs to be something functioning as one in enough ways.

If the universe is infinite, then there are infinitely many Boltzmann brains and infinitely many non-Boltzmann brains. Since the two sets are equal, the subjective probability that one is a member of either set is 50/50. What else could it be? — RogueAI

You say you're not a math major, ask a question, then ignore the answer (given by several posters).
The two sets are not equal. To say they are equal is to say that every Boltzmann brain is also a normal non-Boltzmann brain. The two sets would be the same set. This is a contradiction.

"Subjective probability" is a meaningless term. Probability refers to the odds of one thing relative to another, or the odds of something being true or not.

But with an infinite number of possibilities that are not works of literature, including an infinite amount of gibberish; an incomprehensibly large number of combinations of the same number of letters, punctuation, and spaces as Shakespeare's works that are not Shakespeare's works; and a rather large number of works of literature that are not Shakespeare's works... I'd bet against it. — Patterner

So given a die with 10^10000000 sides, one of those sides corresponds to the complete works of Shakespeare, and the rest other things, mostly gibberish. You're betting that if this die is rolled an unlimited number of times, most of those other sides will come up an infinite number of times, but the one side in question will not come up even once.
You're not a math major either I take it. Neither am I, but I can do simple arithmetic at least.

"But if the universe exists over an infinitely long time, extremely unlikely events will happen." — Patterner

Since the universe is infinite in size, it doesn't even take a significant amount of time for extremely unlikely events to occur. I think a comparison of how likely it is to occur within say a given volume of space would help express things better.

I'm sure some will. But there are an infinite number of unlikely events. No reason to think all of them will happen.

Questionable. Some occurrences get less probable over time. They happen because of the infinite size, but if the probability of something drops in half with each passing century, it probably will never happen in a given volume even given infinite time. It all has to do with the area under the probability curve. Is it finite or not? Some infinite series approach infinity and some do not.

There are an infinite number of things those infinite monkeys on infinite typewriters could type. There are an infinite number of things they could type that do not contain the letter E.

But you didn't mention something that they cannot type (pi to full precision is a nice example), and how about anything larger than one monkey can type in its lifetime? The monkeys are not immortal, so the probability of something getting typed drops off sharply after the life expectancy of one. Sure, one monkey lives long enough to hammer out all of Shakespeare. That's why we have a lot of monkeys, which represents infinite space. Immortal monkeys represents infinite time. A single immortal monkey who never stops outputting random characters is all that is needed to eventually put out any finite work of literature, buried of course with gibberish on either side.

I'm going by stuff like this: — RogueAI

The answer there says that the cardinalities of two countable infinities are equal.
That's very different than the statement that two countable infinities are equal, which sort of suggests that there are numbers representing its sizes and those numbers are the same, which is just silly since there can be no such number.

Again I repeat, why is this relevant? Who is comparing two countable infinities? The conclusion of 'equally likely probability' is invalid from a comparison of the cardinalities, as the prime-number example illustrates.

Countable infinities are equal — RogueAI

Tosh

If that were true, if I pick a random whole number of at least 10 digits, odds are even that it would be prime because there are countably infinite numbers that large that are prime, and countably infinite numbers that are not.

Did the you-tube link make a claim of that nature? If so, it would validate my policy to not get my facts from you tube.

Thoughts noAxioms? — Down The Rabbit Hole

Post what you think the video is claiming. If your thoughts are aligned to the bit above, you're on your own.

What exactly are we counting here anyway? The point is not how many universes in the multiverse (which is not countable no matter what kind of multiverse you're talking about), but rather the probability of the physics of this universe being such that BB's are more probable than regular brains. There is no equal probability in any of that.
It seems that neither normal nor BB's are countable in any reasonable manner, especially since empirical measurement is questionable.

The basic test is if SB places a bet each time. She makes money (does not break even) if she bets on tails. This is pretty easy to work out.
If the experiment is done twice (one heads, one tails), she sees heads once and tails twice. That sounds like 1/3 heads to me.

To emphasize this answer, imagine head: they wake her the once, but tails, they do it 100 times before the experiment ends. The coin flip odds are still 50/50, but the odds that on a random waking she sees tails is overwhelming.

Sean Carroll put out a paper explaining why Boltzmann brains are bad
https://arxiv.org/pdf/1702.00850.pdf

The gist is: "the theories that predict them are “cognitively unstable: they cannot simultaneously be true and justifiably believed.

Therefore only theories that predict low probabilities of them can be justifyably believed. The OP makes it sound like the universe must produce these more probably than a standard brain given enough time, which is false. Only under certain theories is this true, and it is a real problem if the theory that is the right one happens to be one of them.

How can we defeat the Boltzmann brain paradox? — Down The Rabbit Hole

I suppose by choosing a theory that doesn't predict a significant probability of them.

In an infinite duration, aren't all possible outcomes equally likely to occur? — Down The Rabbit Hole

No, that doesn't follow at all. I cannot think of a theory that has equal ratio of regular humans to BB's.

PS: I didn't watch the video.

If someone reads about "physics made me do it" and then goes on to behave in all sorts of desperately selfish or immoral ways after reading such, shrugging and citing that it's not their fault, it's physics. — Benj96

Sorry, but your sentence fragment does not parse. You have an "if (...)" without a "then (...)".
If you read my argument above, I show how if somebody uses such reasoning to rationalize their behavior, they will still be held responsible, and thus the actions will be their fault, even if their actions actually are the result of physics, which I don't see how they can't be.

If you disagree with that, then one of the assumptions/definitions (all taken from the Stanford article) must be wrong.

What then is to be said about the time line of their life where before reading about the idea they were more cooperative and good natured citizens and afterward, were reckless and selfish? What changed?

Clearly their reasoning changed. That's how decision making works. Recently acquired data is part of the input to the decision making process.

Thus, it stands more to reason that they made a conscious choice to believe it. And remove themselves from culpability by putting it on the rest of the world/realities set up.

Made a choice, yes. Remove themselves from culpability, no, since culpability isn't something one chooses, but rather a social reaction to one's actions.

If physics was deterministic, why would any given individual sway from varying degrees socially acceptable/moral behaviour to socially unacceptable/immoral and vice versa.

I'm sorry, but how would determinism (or lack of it) be relevant to the reasons why such a sway would occur? I just don't see the connection. Perhaps you're not talking about physics being deterministic, but rather about this guy's beliefs about such changing after reading about it. But you didn't say that.

One would imagine that such a mechanistic and determined existence would be polar and dichotomous from the get go without any freedom to traverse from one side to the other.

I think you're confusing determinism with fatalism, the latter positing that things happen regardless of anything's ability to choose. If that were true, nothing would have evolved brains to make decisions, or better brains to make better decisions.

If the system was deterministic, it devolves into a chaos of extreme egos, arrogance, intolerance, paranoia and inability to forgive or forget, a total lack of empathy (because choice is not anl possible option).

I don't see how any that follows. Lack of free choice is not the same as lack of choice. In fact, free choice (choices made in absence of causal physics) seems to lead to the chaos you describe. That kind of free will is a bad thing in my book, but there are lots of other ways to define it.

Interesting that stuffy archaic Christianity defends freedom of the will as a matter of principle while scientific materialism views humans as automata. — Wayfarer

Depends on what you consider Christianity. The Church certainly defends freedom of will else it would lose its hold on the imparting of judgement, but the Bible seems to make no mention of it that I know of.

Science definitely uses a different definition and presumes we have it. It is important in a few cases like a loophole to Bell's theorem where superdeterminism controls our will to make this measurement or that such that we reach incorrect conclusions, sort of like there being pink elephants everywhere but determinism never lets you choose to look in the direction of one, so they're never witnessed. Physics must make the assumption that that sort of lack of free will isn't going on in order to concludes by induction that there aren't pink elephants on Earth.

Not according to the OT, where god does stuff like "harden Pharaoh's heart" — universeness

I think an omnipotent being could choose to reach in at need and alter the will of somebody when it suits the being's purpose. Of course this blows away determinism if the omnipotent thing can make 2+2=5 now and then because such interference suits its purpose. Momentum is conserved except when God does magic... Every law would have to have that exception listed.

Holding people responsible for their actions is a social process. — T Clark

I agree that it is a social process. I think my argument rests on that.

Thank you all for your continued replies.

Then I'm not sure what you're trying to argue. — Michael

I had to step back and figure that out myself, and it turns out that I'm directly denying PAP, which apparently suggests that: "a person is morally responsible for what she has done only if she could have done otherwise".
This conflicts with the definition of moral responsibility used by the same Stanford article, that defines it as reactive attitudes. Simple substitution yields "a person can be the subject of reactive attitudes for what she has done only if she could have done otherwise", which seems clearly false. Those attitudes will be there regardless of the usual list of cop-outs, them being determinism, lack of free will, or sometimes asserted omniscience. The statement can be made more reasonable by talking of 'justified reactive attitudes" which leaves the door open for the attitudes not being justified in the cases of what I call the usual cop-outs.

Notice I am avoiding declaring a stance on determinism, free will, the objectivity/relativity/absence of right and wrong actions, etc. I have opinions on these, but they seem irrelevant to the point being made.


While I'm on it, I protest the usage of past tense in the phrase "could have done". Free will should be about being able to do otherwise. Putting it in past tense makes it sound like the free choice depends on your ability to alter something already done. So it should say "Free will is the ability to do otherwise" which is still a poor definition (not something I'd find desirable to have), but at least it is better than the past tense version.

Given your underlying assumptions, I would say you are correct. — T Clark

Trying to guess which assumptions you're talking about. That behavior is a product of physics is a sort of assumption, but even the dualists suggest only that there's more to physics than what is in the physics books, yet to be discovered so to speak.
That love can be described in terms of particle interactions is not something I'd ever suggest.
My point seems to be summarized in the reply to Michael above: A self-contradiction in the PAP article on the Stanford site.

What does it mean to be held responsible for choices made? — Michael

The OP mentions the 'Strawsonian definition", on which the Stanford article is based:
"To be morally responsible is to be the proper object of the “reactive attitudes,” such as respect, praise, forgiveness, blame, indignation, and the like"
The definition sort of implies the attitudes of peers, but does not explicitly call it out.

I admit that my argument hinges on this definition and the argument may not hold with differing definitions, but I like the definition since it makes no reference to controversial subjects like 'right and wrong', be those objective, relative, or nonexistent.

Other claims such as he/she/they made me do it or my mental illness made me do it or the trauma of my life experiences made me do it, etc, are different in my opinion. — universeness

Such claims sort of imply that a kleptomaniac should be permitted to steal since his mental condition leaves him blameless. By my argument, the reactive attitude is still there, hence the responsibility. The course of action as to how to deal with such a person might be mitigated by said mental condition, but it doesn't absolve him of 'blame'.

Are you trying to carve a path from "Avoiding blame with 'Physics made me do it' is indefensible" to not accepting 'extenuating circumstances' as a legal/personal defence.

So many double-triple negatives, it is hard to read that, but ditto to my title. But as I said, mitigating circumstances might influence a reactive course of action, but it cannot erase responsibility.

What main message are you trying to establish, based on someone accepting your OP 100%?

I'm just sick of hearing all the arguments along the lines of "determinism, hence I'm not responsible for anything" which seems to seek an excuse to do anything you please.
I see such arguments in the actual world, but I don't want to bring up specifics for fear of sending the topic down a political sidetrack.

Is it suggested that all psychological, sociological, and cultural motivations and behaviors can be explained and are controlled by physics? So, my wife's scampi recipe; the Constitution of the United States, Benny Hill, psychosis, Adolph Hitler, marshmallows, love, Hello Kitty... can all be explained by physics. Of course not. — T Clark

Why 'of course not'? I mean, it seems to be a product of physics, even if all those things are far more complicated than a more human-explainable interaction between two particles. So if your argument is about our ability to directly express love in terms of particle interactions, I will agree, but that doesn't mean that love isn't a function of particle interactions. If one assumes a form of dualism, that just means that our current knowledge of physics is incomplete. If it really works that way, then there's more physics going on unnoticed despite being right in front of behind your face. It would still be a causal relationship.

In my understanding it comes down to this - Each level of phenomena on the hierarchy of science must be consistent with the laws of the next lower level, e.g. biological processes must not violate any rules of chemistry.

Funny, because the dualists assert just such a violation, which, as I said just above, would mean that our knowledge of the 'rules of chemistry' are incomplete.

By that standard, ultimately everything must be consistent with physics. That's reductionism. That does not mean that you can predict the behavior at higher levels from the processes at lower levels.

Never said anything about predicting, especially constructively. I said it doesn't mean that one cannot be held responsible for choices made. The assignment of responsibility is equally a function (however unpredictable or possibly completely determined) of physics, and it would thus be a contradiction to not be responsible for choices, by definition.

My OP is attempting to bypass all the constructive and reductive arguments and just point out the contradiction resulting from the 'physics made me do it' defense.

Is your OP not dependant on whether or nor the universe is in fact deterministic? — universeness

No, not at all, nor is it dependent on a particular view (dualism or not) of mind. People reach for randomness as a door opening to allow free will in, but all evidence suggests that will works best with mechanisms that produce consistent choices given similar inputs.

I asked you once before if you thought quantum fluctuations were a true example of random happenstance. Your answer was that under classical physics you thought they were, but you offered no reasons for thinking that under quantum physics, they were not.

It's irrelevant here, but at the quantum level, there are hard deterministic interpretations, single world with zero randomness. Bohmian mechanics comes to mind. There are soft deterministic interpretations like MWI with no randomness, but also 'every possibility happens', and one cannot choose your world, so subjectively there is randomness. Then there are interpretations with true randomness like Copenhagen, with 'God rolling dice' as Einstein put it. Given today's list, I don't think Einstein would have favored Copenhagen, but there were not so many choices back when that quip was made.

Is "Avoiding blame with 'Physics made me do it' is indefensible" an issue at all, if we have no irrefutable evidence, that the universe is deterministic or not. — universeness

My argument is independent of whether the universe actually is deterministic or not, let alone being independent of our ability to know if it is deterministic or not.

P1: If circumstances change a belief, then one lacks a sufficient reason for that belief. — Ishika

You'll need to refine this postulate a bit. I mean, I step out of the door and based on the sky I see, I believe it will rain within the hour. That's circumstances, and it is very much a sufficient reason for that belief, even if it doesn't actually rain. Still, I get what you're saying.

Many people use arguments like this to disprove theism. They say that if you were born into an atheist family in mainland China instead of a catholic family in Mexico, then you would hold different religious beliefs.

Such statistics actually constitutes very good evidence against theism. If the choice was a matter of logic and such and not upbringing, there would either be a sort of even mix of all religions everywhere, or (if the deity was real and reveals himself), almost everybody would independently come up with the same religion. But no, it appears in clumps, a strong indication of cultural influences.

Some statistics lie. Somebody from Mexico might profess catholic beliefs because professing otherwise would cause ostracism from society. So there's plenty of church goes that are there for the social acceptance and interaction, and not because they hold actual belief. Much of the founding fathers of the USA for instance fall in this category.

However, if I believe that affirmative action is bad because it is unjust and unequal, then my opposition would stand no matter my race, which means I have a good reason for that belief.

Except the alternative is also unjust and unequal. There's no obvious 'just and equal' solution to the problem it is trying to solve.