But that's exactly my point. How can they be identical?


Imagine a spot near the edge of each bubble. The same spot in both (as you assumed both identical). From these identical spots you can look to the space outside the volumes. You will see different things, as the outsides diverge. Then how can the insides be identical?

Yeah, if you're living near the edge, you will see different things outside. But if you're living in the middle, you will see the same thing.

But you can see the one living near the edge.

Yeah, nah. They're living many light years away from you. You'll be dead by the time you can see them and the divergence.

Maybe that's why we aren't seeing other living creatures around us

Yeah, I'm talking about the single infinite 3D universe introduced in the OP: "In an infinite universe <...>". I think you contributed with the idea of a 4D space with many 3D universes, but for the purpose of the OP I'm assuming a single infinite 3D universe. I'm also assuming that the universe has a finite age and it's expanding similar to our universe. — pfirefry

This is by far, my favorite stuff to discuss. I am on a few 'cosmology' sites, with a wide range of folks who discuss this stuff. I also enjoy TPF as I am also interested in the philosophical aspect of all issues. I watch Sam Harris, Dan Dennet, Steve Pinker, Jordan Peterson etc on YouTube for the more Scientific side of Philosophy and I watch recorded lectures on the classical philosophers and on those who became historically well known for philosophy since. On TPF I see how their musings are debated by many contributers from Garret Travers through to Agent Smith et al. I do like the cosmological threads the best however.

If you think that the Universe has a finite age (and I agree) then how do you arrive at 'infinite?'
If at an earlier time it was smaller then it expanded then an infinity of time would have to have passed for space to be infinite due to the spacetime concept. We still move towards a future, every second so has enough time passed for space to be infinite? is it possible for space to be infinite, given the constraints I am suggesting? I think that this suggests at least a 4th extended spatial dimension. You confirm your own doubts about 'infinite space' with:

I don't find the idea of infinity very realistic. — pfirefry

The finite age allows us to consider the regions of the infinite universe so far removed from each other that there is there no way for them to interact with one another. If they sent beams of light towards each other at the moment of the Big Bang, the light wouldn't have reached the destination by today. — pfirefry

Yep, I agree but only if 'information travel' and movement from A to B at light speed is the only way one part of 'existence' can 'affect' another. The only way I can conceive this is that I can touch two parts of an object at the exact same moment in time, using two fingers as I can stand above it. If there is a 4th extended dimension then I wonder if any two parts of its 3D components can be affected instantly due to the existence of the 4th D. I can touch any two parts on a 2D shape, within the extent of my arms.

This sets the ground for a multiverse within a 3D universe. — pfirefry

Yep, If we define a single universe in accordance with light speed since 'our singularity' and reject Mtheory and the brane idea with many singularities starting many universes.

Exactly. I'm assuming that singularity was uniform. When the universe started expanding, the areas of space appeared everywhere at the same time, so that space was already infinitely large the moment it appeared — pfirefry

I don't understand this one? Already infinite space? so why to we need inflation and expnsion?

I'm allocating a chunk of space in which an observer will exist. This area of space can be the size of our observer, or our planet, or our galaxy. Arbitrarily, I chose the size of a Hubble volume to connect with the OP. I will introduce the second circle to outline the observable/detectable 'section' of the universe, where the first circle acts as the observer. — pfirefry

Yeah I get this, the observer can't get any information from anything moving away at faster than light speed, even if the observer was traveling at light speed, light would still move away from the observer at light speed. This is a really difficult concept. Especially when trying to think about light source.

let's say that yeast bacteria is living inside the dough. It can travel through the dough over time, regardless of its expansion. — pfirefry

Yep, I understand but does the yeast bacteria move through in a 'ghost like' way. Some quantum effects seem to do this OR does it compress/warp the space around it to 'move through it'. Perhaps I warp surrounding space in some way to allow me to move or be dynamic in anyway. To be animated is an old meaning for 'spiritual' interestingly.

The first circle is the boundary of your heart. — pfirefry

I digress but, this should be a line in a song :lol:

It just expands because new space appears for it to expand into. New bubbles of space are forming in the dough, while no new dough is being created. We don't know where the space is coming from, but we know that it just appears and it causes the expansion of dough. It's not important where the space is coming from for the purpose of the OP. — pfirefry

Yeah, I share your feelings of frustration at this point. We just don't have all the answers yet so conjecture or projecting possibilities based on what the current evidence gives us, is all that Max Tegmark is doing and I for one, label him a 'Truth Seeker' for that. You are doing similar thinking in your own head. Another truth seeker! Keep going! Someone will make progress eventually. I have FAITH in that, but I would never insult it with the God label.

I don't understand your last comment.

Suppose we look at a galaxy near the edge. Far away in spacetime. My copy does the same. The galaxies are different because of interaction with stuff outside the two volumes. But if I see a different galaxy than you, we are not the same anymore.

If you start with two identical regions in infinite space, same particle configuration in phasespace, then... indeed there could be two or more copies of you and me if the diverging surroundings find themselves at distances greater than the time it takes light to travel from there to you and me typing. If not, I could look through my 80 meter telescope and see a different thing, far away.

Enter entanglement...

It just expands because new space appears for it to expand into. New bubbles of space are forming in the dough, while no new dough is being created. We don't know where the space is coming from, but we know that it just appears and it causes the expansion of dough. It's not important where the space is coming from for the purpose of the OP. — pfirefry

That's the problem with dark energy. It generates new space, apparently. How can that be? Dark energy doesn't have a related particle. The inflaton? Maybe. What if our (finite) universe is a 3D structure immersed in a 4D structure. Say all matter is confined to this 3D structure. And that the vacuum energy (closed propagators in Feynman diagrams) give this 4D substrate space negative curvature (repulsive gravity). Then the particles in the (two) universes will accelerate away from each other. I imagine the hole of a torus. There is negative curvature there. On the Planck-sized mouth of a 4D torus two 3D universes might be ejected, two big bangs, like two 1D circles can be ejected from the mouth of a 2d torus. If the torus is open on the outside, the circles (universes) can accelerate to infinity and a new bang can start at the mouth.

Suppose we look at a galaxy near the edge. Far away in spacetime. My copy does the same. The galaxies are different because of interaction with stuff outside the two volumes. But if I see a different galaxy than you, we are not the same anymore. — Cornwell1

I don't conceive the same depth of problem with this general issue of a replicant.
In general, replication is fundamental in our own local. DNA does it all the time.
Cloning claims that its possible to replicate humans in the future. It's already been done with sheep etc.
Surely the idea of 'multiverse replication,' is to deal with the mathematical posit that every member of a set must be an outcome. Every possibility that can happen must happen. But the point of replication would be the only point where 'identical' is true. Divergence will occur one instant after the state 'identical.'

Dark energy doesn't have a related particle — Cornwell1

Maybe it does or perhaps we will never find the graviton either and dark energy like gravity may be a 'consequence of the structure of the Universe' rather than a force. Perhaps gravity and dark energy are both different aspects of the same affect.

Well, in fact there could be two identical parts in the universe. Imagine the space that banged into existence. It had a diameter already of 10exp11 times the diameter of the observable universe. If this universe comprised two identical halves then the centers of these halves are surely still the same, so J realize now, thanks to pfirefry (nice name, but WTF does it mean?). I almost started a chapter to attack Tegmark, but I have to find new ways now. Maybe entanglement, which is non-local, will do. But copies on both sides of the 4D mouth I have in mind (I'm
a bigmouth!) will always stay the same, even if made of antimatter.

Dark energy has no related particle. It must be a particle that can curve space negatively. Virtual particles can have negative energy or mass, so.

The first circle is the boundary of your heart.
— pfirefry

I digress but, this should be a line in a song :lol: — universeness

:grin:

The bloody bull at the center
Hit by my poisoned arrow

Well, in fact there could be two identical parts in the universe. Imagine the space that banged into existence. — Cornwell1

But why would two identical parts, remain identical over time. Why would every event in each remain identical? Under which scientific imperative?

It had a diameter already of 10exp11 times the diameter of the observable universe. — Cornwell1

Are you referring to the singularity here?

Dark energy has no related particle — Cornwell1

But this is just your opinion, there is no accepted proof of this.

But why would two identical parts, remain identical over time. Why would every event in each remain identical? Under which scientific imperative? — universeness

Well, if two halves on a 2d sphere contain particles that have identical relative positions and velocities , then they will develop identically. From the circle where they meet the two halves will diverge until both halves will be different.

Are you referring to the singularity here? — universeness

I assume the singularity to be the Planck-sized mouth on the 4d torus on which two 3d universe inflate from Planck diameter into 10exp11 times the size of the observed universe (about 90 billion ly).

Dark energy, the negative curvature of space, can be caused by the virtual particles in QFT. Real particles yield positive curvature.

So here we go guys:

Title: Tegmarks Lover

Verse I
The first circle is the boundary of your heart
The bloody bull at the center
Hit by my poisoned arrow
Will the sound replicate baby?
Can ya hear me now?

Chorus:
We cant talk no more baby
There are too many stars
The distance between us
Is just too far

Do you think we can finish this song before we finish with this thread?
All titles and words are fully open to review and editing by anyone.
No copyright is claimed!
Life has to be as fun as we can make it!
Hey! maybe that line should be in the song!

Well, if two halves on a 2d sphere contain particles that have identical relative positions and velocities , then they will develop identically. — Cornwell1

I assume you mean 3D sphere. You cant get a 2D sphere. But two such particles can still have some different attributes? You are talking about aspects such as spin, charge, mass, wavelength etc but there could be other attributes that we have not yet identified which are different in each one.

I assume the singularity to be the Planck-sized mouth on the 4d torus on which two 3d universe inflate from Planck diameter into 10exp11 times the size of the observed universe (about 90 billion ly). — Cornwell1

So does the singularity still exist as the nexus between your two universes?
I know you cant graph a 4D torus but what shape do you posit for the two universes?
Flat? But what is flat in 3D? a cube or cuboid?
Is this 4D torus what you suggest is the inside volume of the ballon?

I know you cant graph a 4D torus but what shape do you posit for the two universes?
Flat? — universeness

Sorry, earlier you said your universe was curved, so curved in what way? curved and closed?
I think you said before that you think the universe is closed. If so do you mean closed in the form of your 4D torus and if so, what shape would that cause in our 3D universe?

Yes, say two halves on the sphere of the balloon. I think that they live parallel, separate, simultaneous lives makes both non-identical. How can a parallel copy of you and me be the same as us?

So does the singularity still exist as the nexus between your two universes? — universeness

Yes. Behind us, in the fourth spatial dimension. Imagine the 2d case of the torus (the outside is not closed though). From the small mouth, two 1d circles (two universes) can spring into being. They contain all matter and the circles get larger when diverting from the center away. Space seems to appear in both of them. Expansion. At the same time, the both influence the curvature around the mouth. When they have accelerated into infinity, a new bang can inflate two new universes into being (two circles). The center of a torus has negative curvature (repulsive gravity).

If so do you mean closed in the form of your 4D torus and if so, what shape would that cause in our 3D universe? — universeness

Yes, two closed 3d universes moving on the 4d torus. The outside of the torus is open though and extends to infinity. Two 4d spaces connected by a 4d wormhole, the singularity, fountain of life.

Probably like most people, I read each word/label you or anyone else types, access its traditional meaning and try to garnish an overall understanding of the idea/opinion being expressed. But I am 'tripped' by combinations such as '1D circle,' 'space seems to appear,' 'accelerated into infinity,' etc.
I cast no blame for this as I have the same struggles.

So far, I am unable to conceive your 'big picture' of the structure of the Universe but I would ask the following.

Do you think there has only ever been one singularity in existence and if so, what's at the center of every super-massive black hole?

How can a parallel copy of you and me be the same as us? — Cornwell1

By parallel, do you mean 'can never meet?'
"You and me be the same as us?"
In the literal sense, I think these are synonymous aren't they?
If I was standing next to you then I could use the reference 'You and me'
If I was talking about you and me to a third party then I might use the label 'we' or 'us'

So you must be talking about 'how a third observer' would view identical copies of you or me, in which case I would use 'them.'
If they could observe both the copy and the original. I think they would see them act differently(diverge), but are you sure Tegmark is suggesting they would be tied to a kind of 'Simon says' duality of action and that every event that happened to one copy would happen to the other in the exact same order? I don't think he is claiming that but I say that not having read everything he has written about his Level 1 multiverse.

Do you think there has only ever been one singularity in existence and if so, what's at the center of every super-massive black hole? — universeness

The center of a BH is no singularity as the one at the center of the 4d torus. In a bh all matter is compressed to a planck volume. With point particles a true singularity would have formed. I don't think particles are point-like though. But neither strings. You can think of them like Planck-sized circles on a long closed cilinder. But the circles replaced by small 3d torus shapes, a 6d space of which 3 dimensions are curled up into circles, ie, an S1xS1xS1 torus. Like this they fit around the Planck-sized mouth of the open 4d torus. They are tied to a closed 3d space, a sphere, that is wrapped around the 4d mouth like a 1d closed line, a circle, is wrapped around the mouth of a 2d torus.

Ok, well thanks for trying to make your hypothesis clearer to me.

Tegmark litterally says that there exist collections of particles and surroundings that are identical. A twin that cts, thinks, and feels like you or me. So the other me is typing this words too, at the same you. But two copies can't be identical.

Like this they fit around the Planck-sized mouth of the open 4d torus. They are tied to a closed 3d space, a sphere, that is wrapped around the 4d mouth like a 1d closed line, a circle, is wrapped around the mouth of a 2d torus. — Cornwell1

Is this as close to pornography as physics gets? :gasp:

Incoming message:
"The father of modern-day bouldering is kindly requested to go hang on one arm on a branch of the closest tree in the neighborhood."

Mr. Gill! 84 and these thoughts? Shame on you! :grin:

Well if that is what he suggests then I would require irrefutable evidence, that he is correct.
If that is not available then I would put this idea of duplication of events to the levels of the entire history of the Earth or even an individual life, as nonsense.

Is this as close to pornography as physics gets? :gasp: — jgill

You should have visited the last year college at university here... :mask: