My thoughts are that I'd like to play poker with you.

Hmmm. What I think we've observed is red shifted galaxies relative to us. It could be that those closest to the centre (we need a centre for a big bang or for a new convergence place) are moving faster than us toward the centre, just as those further from the centre are moving slower relative to us. It would make sense as gravity grows stronger - almost like a singularity toward the centre. — MikeL

If this were so, the red shift would be greatest towards the mass that is pulling everything in since acceleration would be greatest there. Smaller red shift in the opposite, and blue shift in the other 4 directions as things parallel to us all get sucked closer to this mass. This tendency is called tidal force: expansion in 2 dimensions and contraction in the other 4, and is a signature of a strong gravitational field.

As for us or the other galaxies dong the receding, it doesn't matter if it is us or them receding. Those are just different choices of frames. Point is, separation between us is increasing.

I find it reassuring that not any objection to the consensus is blindly accepted. I understand the need for Science to be conservative, and set the bar higher. At the same time, discussions of what seems to be an eternal truth should not be silenced. — Hachem

Challenging accepted view is fine, but doing so without bothering with the work of making some predictions (this idea makes plenty, and they all fail) is not science. Great minds do the work when positing something new. The rest of us get educated.

The universe hasn't changed in terms of physical laws since animal life emerged.
— fdrake
We have no evidence of this one way or another.

Nothing requires consciousness
— fdrake
No evidence one way or another. — Rich

You seem to be unclear on the difference between evidence and proof. Yes, there is no disproof of idealism, but evidence abounds. It is also illogical to debate idealism since you're having a debate with a consciousness that cannot be experienced, and hence doesn't exist.

Probabilistic is not determined. — Rich

Didn't say it was.

There is zero support for determinism.

So you've repeatedly asserted. You are free to deny any evidence that does not convenience your faith.

You and the OP late looking for some hidden variables that are deterministic.

I think hidden variable interpretation is bunk, but it would be an example of deterministic physics if it were the case.

QM reigns and it is probabilistic. Zero determinism. — Rich

Probabilistic is not undetermined. For that matter, determined does not mean determinable.

an intent and subsequent action may have quantum origins but the effect is macro-scale (the world we see, hear and feel) and this world is deterministic.
— TheMadFool

People often say this. They can't, however, model it.

Planning would be pointless if the world weren't predictable.
— TheMadFool

On the contrary: if the world were predictable, there would be no need to plan. — mcdoodle

Agree with TMF here, sort of. The world is for the most part predictable, but that does not in any way imply deterministic.

Planning would indeed be pointless of the world were not predictable. No point in planning if there is zero idea of what's to come. Most life forms are evolved to be excellent predictors despite the imperfect nature of any prediction made. I draw breath not because it benefits me, but I predict it will benefit me in 15 seconds.

If the world were no predictable, planning would be pointless I would think.

You mean, for example, we can derive the laws of motion from QM principles? — TheMadFool

Yes.

I thought for a choice to hold the math has to make sense.

The math makes sense in all of them, else they'd not be valid interpretations, but rather disproved hypotheses.

Fine, then give some evidence for determinism. — Rich

The primary one that drove Einstein which is relativity of simultaneity. There seems to be no ontological status difference between different times of a given object. Is it possible that Napoleon of 1781 does not become emperor and die 40 years later? Quantum theory is oddly mute on this point.
To say that 'it could have happened differently' is very interpretative language and implies that things can be put back into a not-yet-happened state, in violation of the ontological status consistency suggested by Einstein's work.

Of the three more major interpretations of QM, two (hidden variables, no-collapse) are deterministic. But this is evidence only of consistency, not direct evidence for or against determinism.

On a less scientific and more philosophical front: A non-deterministic universe seems in need of creation, meaning it is a byproduct of a larger universe in which it was created, and thus not really a universe at all, but just another object/process among other things. That's a circular inconsistency that is too often dismissed by asserting that is against the rules to question the logical consistency of the parent universe.

Some qestions i have for anyone with environmental and wether sciences knowladge is:

Can the relase of methane cause widespread increase in forrest fires and how does it work? — XanderTheGrey

Have not heard this. Hmm, climate change makes it rain less on certain forests and increase fire risk? This is just a guess.

Can it cuase an increase in hurricanes and or tornadoes and how does it work?

Any global warming makes for warmer oceans, and ocean heat is what fuels hurricanes. Tornadoes is different dynamics, and I don't see a methane connection. Methane or global warming has little effect on conditions of cold air above warmer air.

Will it effect lightning? In what way, and how?

Methane would seem to have no effect on this. Not like concentrations would reach levels where it could ignite.

What temperature can a human being survive at individually?

About 35c skin temperature I'm told.

The standard determinism story (and all if it is just a story) is that if everything is known coupled with the musical Laws of Nature then everything can be known. — Rich

It is trivial to disprove such epistemology even given a simpler natural law that is not probabilistic. Determinism is not a claim of what can be known.

as for determinism zero evidence to support it. — Rich

No proof perhaps, but zero evidence is a pathetic claim. There is in fact quite a bit of evidence for both sides of the debate. You seem to have chosen a side and justify that bias by refusing to acknowledge existence of evidence to the contrary. Cherry picking is always a good way to bolster your biases, but it sucks as a method for real discovery. Embrace contrary evidence and win past it. Hiding from it only demonstrates that you fear to face it.

If you are a determinist, — Rich

Haven't stated my position. Not sure if I have one,
You have a stated faith in God. I suppose that usually necessitates a non-deterministic stance, but said stance is then backed by the faith, not by any evidence.

I guess if everything is unpredictable then there is zero evidence to support determinism. — Rich

And you repeat the mistake again.
Determinism makes no claim of predictability, and lack of predictability is zero evidence against determinism. Is that the 'quite clear' evidence against it?

It just becomes a matter of faith, — Rich

If the evidence was as clear as you claim, it would not be a matter of faith, but rather a matter of holding a belief in a position inconsistent with evidence.

And as science understands the behavior of matter it all probabilistic, which hopefully answers the OP. — Rich

It does answer the OP, but the OP wasn't about determinism. I'm saying that your dragging that into the conversation was irrelevant to the subject at hand.

Determinists? You know, all those who believe that everything is fated ever since the Big Bang blew its top. — Rich

They don't claim predictability though, and your arguments are against that perceived claim of predictability.

In any case, science is quite clear, there is no determinism though it doesn't stop scientists and educators from perpetuating the belief.

What 'clear' evidence have you against the determinism aspect? The fact that we can't predict things (trivial, isolated systems for instance)?
For that matter, what evidence is laid out there FOR determinism, that it would be perpetuated as fact as you say is done?

If course. Old ideas die hard. There is no such thing as precise prediction of anything. — Rich

Who is clinging to these old ideas of perfect predictability? Anybody who knows their mathematics, never mind their physics?
Or is your stance that lack of predictability implies lack of determinism that you so spit against?

Materialists-Determinists who view themselves as objective scientists seem to have a very difficult time with their faith. — Rich

Materialist-Determinist is a philosophical stance, not a scientific one. Science does not depend on the stance, even if some scientists hold the stance in faith, as you do whatever yours might be.

Quantum physics, which I don't understand, aside, the world on the human scale (macroscopic world?) is governed by fixed natural laws of matter, energy and force. — TheMadFool

Quite the opposite. Natural law is derived from QM, not the other way around.

Even the roll of a dice or the toss of a coin are governed by laws of mechanics.

In a pure Newtonian set of physical rules, this is true.

I've heard that, for instance, radioactive decay is objectively a chance thing - which atom will decay is entirely random (so they say).

QM does not say it this way. This is interpretive language, which you are free to use, but such language is not QM.

He is restating a 17th century philosophical faith that someday science will discover the Laws of Nature that will enable scientists to predict everything. — Rich

Even in hard deterministic universe without QM, such predictability is easily disproved. Inability to predict has nothing to do with determinism or lack of it. You seem pretty bent on a different stance.

I'm saying that probability is deeply linked to ignorance. The process by which we conclude whether or not a certain process/thing is probabilistic or not is exclusion.

What I mean is, first, we assume the existence of a general law that governs a process. If we find one, we name the law and express it mathematically. Only if not, are we warranted to think the process/entity is probabilistic. — TheMadFool

Wait, what if the law above is a probabilistic one? It means the mathematical model has probability baked in. Interpretation of that model on the other hand is open. There are multiple consistent (valid) interpretations, and if it is meaningful that one of them is more correct, then that's where the ignorance comes in: There is no way to choose among valid interpretations, so the typical course of action is to choose based on what you want to be true.

Mr. Reductionist says that the actions and behaviors of anything in that ecosystem can be explained by the motions of its constituent particles, since it's all made of matter anyway. — Pneumenon

While I do think the situation can be reduced to particle physics, at no point in that view is there a 'thing' which does an 'action'. There is never a definition of a fist or the anger that drives it. I voted for talking past each other.

I voted substantive mainly because you seem to have ruled it out by setting up the idea that an ecosystem is equivalent to a bunch of billiard balls. So the image you provoke in my mind is of a deterministic system, such as life-game. In such a world, glider guns, gliders, and all the myriad more complex constructions are strictly reducible to the deterministic laws. In such a world, Mr Irreductionist is simply wrong, and the disagreement is substantial.

On the other hand, if the world is not deterministic, Mr reductionist is simply wrong. — unenlightened

The lack of determinism seems to have little impact on reductionist particle descriptions of an ecosystem. OK, in neither the reductionist nor the holistic view can future states be determined, but absent agency from outside the ecosystem (which would be information actually leveraged from the dice rolling), behavioral states seem to follow the classic predictable rules of billiard balls. The only quantum amplifiers I know about are those in physics labs.

Will try to take the time to watch that. Would prefer a transcript.
<edit> Will be looking through the atlantic link instead. Far better.

I tend to agree with the base concept: The world as we see it is effectively mind-derived naive realism, and the thing-in-itself behind snakes and trains bears pretty much unrecognizable correspondence to the 'desk icons' that are our representations of them.

But I draw no dualism conclusions from this. Mind still seems to be a physical process supervening on this thing-in-itself matter. I see no reason to suppose that mind is special in this sense. A machine observer would have the same naive realist view, even if it comes from the biases put there by its programmer instead of evolution. I want to see Hoffman's take on that to see what conclusions are drawn on this front.

Found a pretty comprehensive article on the problem. Goes on for 5 pages and leaves few stones unturned, including the accretion suggested this thread posits. Also higher Earth spin (shorter day) and all sorts of physical and not necessarily biological explanations. So looking only to the biologists might indeed not be the right thing.

It considers a different gravitational constant G, and doesn't reject it for enough reasons. If G was less back then, the Earth would be cold because it would be much further from the sun. The author seems unaware of that part, but at least is unwilling propose such a fundamental hit to physics.

Some interesting points: The descendents of dinosaurs are birds, most of which are already far less dense than water. Maybe the dinos had that as well and simply didn't mass as much as would an alligator that size.

In the end, a pretty plausible explanation relates to the know small variance in temperature between various latitudes back then. The poles were nearly as warm as anywhere else, suggesting a much more dense atmosphere which would buoy up the large creatures. Maybe Earth was more like Venus back then. What evidence do we have against that? Such a suggestion implies we're losing atmosphere quickly and there won't be much left after not too long. They already predict the oceans will be gone soon, but I thought it more from a warming sun than from just losing it all to space.

I did acknowledge that earlier in the thread. It remains mysterious, however, why the mega-fauna of that age was so much bigger than anything that exists today. Some of the brachiopods weighed as much as today's whales. I was wondering if there is any global change that might explain this disparity. — Wayfarer

So look to the biologists for answers. As a side note, I visited the Alaskan rain forest and also a small patch of woods just outside that zone which we dubbed 'honey I shrunk the kids'. Many plants were recognizable (the same ones I have at home), but about 4x the size I normally see. The dandelions stood about a meter high for instance.

Concerning gravity: Of the eight planets, five of them (including Earth) have pretty similar gravity, but the closest one to us is Saturn, despite massing over 100x as much. So additional mass alone does not necessarily translate to a weight difference. Mars and Mercury weight are almost identical at 3/8 Earth, and Jupiter is in a class by itself at 2.5x.

2. Then, according to Gödel’s theorem, F cannot prove its own consistency.
3. We, as human beings, can see that F is consistent.
4. Therefore, since F captures our reasoning, F could prove that F is consistent. — deepideas

3 is worded entirely differently. You've not stated that F cannot see that F is consistent, nor that humans can prove that F is consistent. So nothing seems to have been demonstrated at all. Line 4 does not follow at all.

Perhaps you can restate your steps using consistent terms.
I did not read linked page. The argument posted here thus far has not enticed me to do so.

All the responses so far seem to revolve around a good-female partner.
In absence of her suitability as a partner, what might be meant by a 'good woman'?

↪noAxioms

The first, and best-known, ontological argument was proposed by St. Anselm of Canterbury in the 11th. century C.E. In his Proslogion, St. Anselm claims to derive the existence of God from the concept of a being than which no greater can be conceived. St. Anselm reasoned that, if such a being fails to exist, then a greater being—namely, a being than which no greater can be conceived, and which exists—can be conceived. But this would be absurd: nothing can be greater than a being than which no greater can be conceived. So a being than which no greater can be conceived—i.e., God—exists
— Stanford Encyclopedia of Philosophy

I'm thinking conceive = imagine

Am I wrong still? What's the difference between ''conceive'' and ''imagine''? — TheMadFool

I stand corrected. It really was about an imaginary or conceptual god.
From a strictly logical standpoint, the argument seems to fall apart since it references an existing god, and the nonexisting one does not meet the criteria specified. In effect, the argument seems to say that if God doesn't exist, he wouldn't be God, and the conflict stated isn't conflicting at all.

From a modal logic point of view, a world in which there is this god would be consistent, and a world in which there is not this god is also consistent. The argument seems to be a simple tautology. St Anselm tried to argue that the later world is inconsistent there because the nonexistent god did not meet the existing-god requirement.

To state that God is the greatest being imaginable is to state up front that God is imaginary. Surely an existing god would be greater than the limits of our imagination.

I don't think you got the argument right. I don't think it was built around imagination like that. Try to restate it.

When we hear that a certain experiment 'proves relativity' we get the impression that scientists are one step closer to establishing relativity as absolute reality. — FreeEmotion

What do you mean by 'proves reality' and which scientific finding lays this claim?
It sounds like a philosophical assertion, and you're hearing one person's asserted interpretation of some particular finding, and not what the experiment actually demonstrates.

So in the above example, it is possible to synchronize clocks, and it is possible to measure the one way speed of light? — FreeEmotion

Given an arbitrary choice of frame, yes, this measurement can be done.
Given a different frame choice, the chock synchronization would be different and therefore the time between the same two events E1 and E2 would be different, but the spatial distance between them would be different as well, so the measurement of light speed would still come out the same each time.

I'm curious what percentage accuracy? — FreeEmotion

Within 10% error

If we have the spatial separation between events E1 and E2, and know the times at E1 and E2, we can calculate the light speed. (not measure?). Why assume it a constant when we are trying to measure it in the first place? — FreeEmotion

This can be done, but the synchronization of the two clocks is frame dependent. For that matter, so is the distance measurement since E1 and E2 are not simultaneous.

Now I know that the clocks need to be synchronized, or the other option is slowly moved apart.

If we are able to have control over how fast the clocks are moved apart, we can establish the error bounds due to non-synchronization and take this into account.

Slowly moving apart doesn't necessarily work. You start at a midpoint and move the two clocks symmetrically in opposite directions. That defines a frame, but the two clocks stay synchronized despite the speed at which this might be done. Now you can measure your light speed. Painful way to do it, but valid.

Why "compute" and not "measure"? — FreeEmotion

If you use synchronized clocks, it is a measurement. If I know light speed, I can compute the time and don't need the clocks. But synchronization is frame dependent.

All the thought experiments you reference assume as a postulate that light speed is constant. None of the thought experiments involve the measurement of it. I have performed a light-speed measurement in a lab exercise using the length of a hallway and only an RPM meter as my clock. We got about one digit of accuracy with that setup.

It concerns the speed at which light is transmitted. It's known that the speed of light is different in different mediums, and this involves refraction. I believe the classical way of understanding this, understanding light as waves, involves the wavelength of the light. The quantum understanding of this difference in speed involves the light photons being absorbed and reemitted by the atoms of the material. — Metaphysician Undercover

Didn't know this. Looked it up, and pretty much yes. They said that light was absorbed by the lattice, not the atoms, as evidenced by the absence of absorption lines in the refracted spectrum.

I believe that when light is transmitted through a substance, there is an interaction between the electrons of the material, and the light energy. — Metaphysician Undercover

I've not heard of anything like that, but I'm no expert either. All descriptions I read are from light being absorbed, not just passing by if it was merely being transmitted through a material that passes light like glass. Yes, glass interacts, but not by giving off electrons.

What does any of this have to do with relativity thought experiments that F-E is asking about?

Let me clarify my argument:

x and y are omnipotent beings.

x being omnipotent can do anything. — TheMadFool

You need to redefine omnipotent then, since most-powerful carries no implication of 'can do anything'. You asked if the logic was sound, and I responded without preconceptions of what alternate definitions you gave.

OK, so you're going with more classic definition of omnipotent then. Then we're back to true-Scotsman fallacy. God is not dependent on your insistence of certain qualities. God need not be all-powerful to do any of the acts attributed to God. God needs only be sufficiently powerful, and maybe this universe is a failed practice attempt in a class project in which a C- was given.

So you're saying the most powerful being is NOT an all-powerful being? So, in what sense is the most powerful being the most powerful if it's not all-powerful? — TheMadFool

My example was the most-powerful bunny, which by your definition is God if there's nothing more powerful than it. There's plenty of things it cannot do (not all-powerful), but that doesn't preclude it from being the top of some arbitrary ranking according to power.

My postulate is omnipotent beings exist. My assumption is that there are two. All propositions in my OP follow logically from there being two omnipotent beings. If they contradict each other that much the better as contradictions are proof that there can only be 1 omnipotent being. — TheMadFool

Then none of the other statements follow from your one postulate of god being the most-powerful and there being two of them.
For instance, 3: X being omnipotent does not imply that X can kill Y. It just means Y is no more powerful than X. There is also an unstated assumption that X is a living being than can meaningfully be dead or not dead.
5: Inability of Y to be dead similarly does not follow from Y being omnipotent. The logic is not valid at all.

None of the numbered points follow from the postulate you gave.

If preconceptions are allowed, then Poseidon is not a God because Zeus is more powerful. Sounds an awful lot like a no-true-Scotsman fallacy.

Omnipotent being = The most powerful being

God(s) is/are omnioptent being(s).

Assume: there are TWO omnipotent beings, x and y.

1. x is omnipotent
2. y is omnipotent
3. If x is omnipotent then x can kill y
4. If x can kill y then y can be dead
5. If y is omnipotent then y can't be killed
6. If y can't be killed then y can't be dead
7. y can be dead AND y can't be dead (contradiction)
So, our assumption that there are TWO omnipotent beings is false. This reasoning can be applied to any number of Gods.

Is my proof sound? Is there another proof that there exists only 1 god. — TheMadFool

First of all, you need to label your points as postulates or conclusions. Hard to tell.
Second of all, the soundness (or lack of it) of your logic is hidden by the biases assumed by the reader. I for instance agree to none of your postulates or definitions.

So never mind my preconceptions. You've reduced deism down to a game of Stratego and defined god as the most powerful being, even if just a bunny rabbit, so long as it is at least as powerful as any other being.
I already see a flaw in the soundness in that you've left unstated that there are any beings at all. If there are no beings, there is no most-powerful one that would be the god.

1 and 2 contradict your stated goal: You postulate two identically powerful beings in hope to drive it to contradiction. All very well if it can be done.
3 does not follow, so I assume it is another postulate. 3 also implies that if there are two identically most-powerful beings, they can kill each other.
5 is contradictory with 3. 3/4 says they can be dead if both most powerful, and 5/6 says the opposite.
If these are conclusions, they don't follow. If they're postulates, they're mutually contradictory and thus proof of nothing.

What is the underlying method of light transmission that relativity ultimately describes? With Newton, you had a mechanism - photons, if relativity is a description of reality, then what is the underlying reality? — FreeEmotion

Relativity is not a full description of reality. A full description would need to include relativity. Light is still photons, and relativity is based on the observed fact that the speed of photons is a constant in a vacuum. It says that they have zero rest mass and frame-dependent nonzero energy. Relativity says little more than that at the level we're discussing here. Look to quantum mechanics for a better description of what a photon actually is.

It is called the photoelectric effect. — Metaphysician Undercover

The photoelectric effect concerns emission of electrons when light shines on a surface and has nothing to do with light transmission mechanism or relativity.

OK, but the distance and time to D1 is not needed, just take the event consisting of light reaching D1 and the event of light reaching event D2, and measure the speed in between. — FreeEmotion

OK, those are events, but how do you measure speed between events? There is no frame-independent definition of that in physics. So you've not specified a frame for these two events. Essentially you need to tell me the spatial separation between events E1 and E2, and given that we know light speed, we can compute (not measure) the time it takes for light to make the trip in the frame you've specified. This is obviously not a measurement of light speed since we're assuming a constant for it in our calculation.

Most (all??) light speed measurements are done via round trip so the emission and detection events are in the same place and the duration can be measured by a clock. That doesn't work if the events are spatially separated. Most of the thought experiments you reference in your early posts assume an already known light speed and from there find geometric implications about the ordering of events and the distance between them.

Let's take the first instance. You have a two detectors, that measure when light passes one and then when light passes the other, D1 and D2. You then have light emitted from an emitter of course, from somewhere outside the detector, along the same axis as D1 and D2.

E >>>>>>>>>>>>>>>>>D1>>>>>>>D2>>>>>>>

It makes no difference if the emitter is moving towards or away from the detecting apparatus, the speed of light they measure will always be the same. Is that correct? — FreeEmotion

You're describing objects, not events. The above setup needs a defined frame to take a measurement, and none has been specified. So for instance, the D1 detector doesn't know when the light was emitted and thus how long it took to get there or how far it traveled. That needs definition, so the measurement of elapsed time can be taken. You've not provided that.
That said, if the experiment is expressed as three events instead of three potentially moving objects which are not events, then the measurement can be taken in any frame and it will always result in the same speed of light.

One explanation is that E, D1 and D2 all are immersed in an invisible medium just like air is to sound, that transmits light by first responding to the disturbance at E and then transmitting the light at the natural speed that the ether transmits light to D1 and D2.

I suppose no alarm bells need to be raised here, this is the explanation involving ether.

This explanation has been falsified long ago. You persist in a model that predicts different results than those that are empirically observed.

What I think I meant was, in the absence of ether, what other explanation is possible? The ballistic theory will be ruled out by the independence of the speed of the emitter.

The wave theory would work, but it needs a medium.

How would you describe the way in which light is transmitted, without using either the ether, waves in ether or the ballistic theory? What is this concept and can it be put into words?

Relativity is not a statement about the mechanism of light getting from here to there. It is about the geometric implications that directly follow from a fixed light speed.

It isn't the case that no solutions can be suggested; suggestions have been made. There are two problems with the suggestions: The tolerable suggestions do not result in enough of a reduction in CO2 and other greenhouse gases such as methane or CFCs to help a lot. The intolerable suggests could (probably) result in large enough reductions in green house gases to limit warming, but would also be extremely, and intensely, disruptive to most aspects of life.

Were we to abruptly stop processing petroleum, stop burning coal, switch to a 95% vegetarian diet, sharply reduce manufacturing, begin massive reforestation projects, reduce total world population, and so on we might bring global warming to a halt -- not instantly, but in a century or so. Some side effects of this approach would probably include: Economic collapse; massive social upheavals including revolutions; extreme dislocations of population; increased deaths due to exposure to heat and cold (not in the same places at the same time); a loss of health care infrastructure; and so on, and on.

"Severe disruptions" should not suggest inconvenience; it should suggest hell on wheels. — Bitter Crank

Indeed. But still a smaller hell than the current path. A preemptive bubble burst might wipe out over half the population, an intolerable situation. But doing only tolerable measures will be far worse. It is the trolley problem. Do nothing and the calamity is 5x worse and history wonders why nobody acted. Do something and the weight of the consequences rests on those that altered the path and history remembers them. Heroes or Hitlers?. Probably depends if those that choose go down with their own ship.

If historians 500 to 1000 years from now are worth their salt, they will understand what we were up against in the 21st century. — Bitter Crank

This rings true.
What we are up against seems to be an inability to even suggest a solution. Pushing for greener energy will help delay the change, but I've never seen a suggestion for an actual way out of this mess. I don't have one myself except possibly the wild-card of the AI singularity.

and experiencing it through an exclusively objective framework — Anonymys

I would have thought that experience is by definition subjective. One can consider something in more objective terms, but that wouldn't be an experience.
The fact that this wasn't obvious means I probably don't know what is being asked in the OP.

So there is no philosophical objection to light, or light waves or photons or whatever, being measured at the same speed no matter how fast the emitter and receiver are moving relative to each other?

None? — FreeEmotion

None, yes. Emission and detection of a photon are two events and events do not have velocities and do not define frames. The relative velocity of the apparatus involved is thus completely irrelevant.

Can the concept of an object whose speed always is your speed + its natural speed raise any alarm bells?

That's the intuition, and intuition is wrong here. All measurements (light in a vacuum) always yield the same number. Light is slowed if it goes through water, glass, etc.

I think the one relevant to this thread is eternal-inflation theory, where other worlds have different physics.
Modal realism pretty much covers any of them. I don't think of think of that as any kind of metaphysical stance, but rather a set of tools for describing them and an assertion that there is no preferred world that is more actual.
For instance, a universe that is undetectable just because it is outside the Hubble-sphere is another world just like the worlds of inflation, QM, or whatever. Is it not real? Some say not.

How is this hypothesis backed up? Because if the other universes are undetectable, then I am guessing that it was not brought up from empirical data. Then was it deduced somehow?
— Samuel Lacrampe

It apparently fell out of some interpretations of quantum mechanics, and later some string theories.
Quantum mechanics is well-established, string theories aren't. — jorndoe

The theory in question is a cosmological one (theory of big things explaining what we see in telescopes), the other end of the scale from QM interpretations (explanations of observed behavior of little things). Oddly, the two are sometimes related, especially in the realm of string theory.
These other universes are not QM worlds, but other spacetimes with different physics and numbers of dimensions and such. They're more an answer to the teleological argument than the cosmological one. The view doesn't answer the first-cause issue, it just puts it further behind our big bang.