Why in the world would Einstein suggest....

@oralloy,

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Expansion of the universe is not the same thing as acceleration within the universe.

Why not? Isn't the universe "expanding" precisely because because the "things" in it accelerated (and are, perhaps, accelerating now).

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@layman,

layman wrote:

Why not? Isn't the universe "expanding" precisely because because the "things" in it accelerated (and are, perhaps, accelerating now).

The expansion of the universe does not involve objects accelerating within space. Rather, space itself is stretching.

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@oralloy,

Quote:

The expansion of the universe does not involve objects accelerating within space. Rather, space itself is stretching.

Yeah, so I've been told. I don't buy it, though. "Space" is now a "thing" which stretches? I tend to think the whole concept is just an ad hoc "epicycle" designed to avoid fessing up to dogmatically prohibited "superluminal speeds."

"No, those things aren't "really" moving apart from each other faster than the speed of light. Actually, they're completely motionless. It's just that the space between them is "expanding."

Yeah, right, eh?

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@layman,

layman wrote:

Quote:
The expansion of the universe does not involve objects accelerating within space. Rather, space itself is stretching.

Yeah, so I've been told. I don't buy it, though. "Space" is now a "thing" which stretches? I tend to think the whole concept is just an ad hoc "epicycle" designed to avoid fessing up to dogmatically prohibited "superluminal speeds."

"No, those things aren't "really" moving apart from each other faster than the speed of light. Actually, they're completely motionless. It's just that the space between them is "expanding."

Yeah, right, eh?

In a way I agree with you on this one Layman.

When we plot the locations of galaxies there is a structure that can be seen. They call these structures filaments where the gravitational influence of the galaxies attract and clump up creating larger and thicker filaments. So when you look at the distribution of matter in the universe on a large scale you don't actually see everything moving away from each other as would be suggested by a uniform expansion rate.

The other problem is, you can't measure space itself, instead you have to look at the objects that we can see. Well these objects are not stationary they are moving. So how can you actually get a proper perspective on expansion when everything is constantly moving? Being attracted in different directions?

I have a different take on why light appears to be red shifted the further out you look. It has to do with gravity itself. We know that light can be influenced by gravity. The higher the gravity the larger the impact it has on light. This impact happens in a shift in frequency thus stretching out the light as it travels through space passing in and out of massive gravitational fields. The more fields this light passes through the greater the shift towards the red, giving the impression the object is speeding away when in fact the light itself was being altered by the gravity fields it passed through.

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GR? Gravity warping space-time? If it's not stretchy, that's out the window, too.

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@FBM,

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GR? Gravity warping space-time? If it's not stretchy, that's out the window, too.

As I've said before, I know very little about GR. But I have been told by seemingly reliable sources that in the so-called "spacetime" of GR the vast majority (like, over 99%) of "distortions" in the "fabric" of spacetime are due to "time" distortions, not so-call "curvature." In the entire diameter of the earth, the "curvature" is said to be less than one inch.

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The density of the universe also determines its geometry. If the density of the universe exceeds the critical density, then the geometry of space is closed and positively curved like the surface of a sphere....

If the density of the universe exactly equals the critical density, then the geometry of the universe is flat like a sheet of a sheet of paper, and infinite in extent....

WMAP has confirmed this result with very high accuracy and precision. We now know (as of 2013) that the universe is flat with only a 0.4% margin of error. This suggests that the Universe is infinite in extent; however, since the Universe has a finite age, we can only observe a finite volume of the Universe. All we can truly conclude is that the Universe is much larger than the volume we can directly observe.

http://map.gsfc.nasa.gov/universe/uni_shape.html

Well, that was 2013, two whole years ago. God only knows how many new theories have come out since then, and what NASA would say TODAY, eh? If you knew that, you still wouldn't know what they're gunna say tomorrow, so, what the hell, eh?

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@layman,

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Generically, the gravitational pull exerted by the matter in the universe slows the expansion imparted by the Big Bang....

Very recently it has become practical for astronomers to observe very bright rare stars called supernova in an effort to measure how much the universal expansion has slowed over the last few billion years...

Surprisingly, the results of these observations indicate that the universal expansion is speeding up, or accelerating! While these results should be considered preliminary, they raise the possibility that the universe contains a bizarre form of matter or energy that is, in effect, gravitationally repulsive. The cosmological constant is an example of this type of energy. Much work remains to elucidate this mystery!...

The main attraction of the cosmological constant term is that it significantly improves the agreement between theory and observation...

http://map.gsfc.nasa.gov/universe/uni_accel.html

Articles I have already posted in this thread argue that the acceleration of expansion would disappear if SR was rejected in favor of an AST (absolute simultaneity theory) as an explanation of relative motion. "Disappear" simply means that it would explain why it's not actually happening in the first place---just a matter of faulty interpretation of the facts.

FBM thinks SR "works." Maybe it doesn't. Maybe it has merely gotten us to the point where these seemingly unexplainable phenomena are thought to "truly occur, when they don't.

I agree with Krumps. Some explanations other than those currently being offered must be better.

Btw, an AST does not dogmatically prohibit superluminal speeds either, so there is no a priori need to "stretch" space with an AST.

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@FBM,

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Then knowledge is impossible and chaos ensues.

I swear you're an unusual case, FBM. Generally speaking, people who are truly "new" to SR have a great deal of trouble accepting its (inherently conflicting) premises. You appear to be the exact opposite. It appears to me that you try to INSIST that SR is "somehow" right, even to the point of interpreting experiments in an idiosyncratic fashion, fully accepting illogical assertions such as "both are correct," and denying every day "common sense" (e.g., that it is the guy on the train or plane, rather than the guy on the ground that is (the one) relatively moving).

Maybe the ignorance and chaos you fear is caused by the acceptance (rather than the rejection) of SR as in any way representative of "reality." Ever think of that?

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@layman,

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I swear you're an unusual case, FBM.

Absolute drivel ! The unusual case is YOU who appears to think modern physics (not to mention Euclidean geometry) needs to conform to classical logic and Aunty Nelly's view of "common sense". If you think SR is "problematic", how do you cope with wave-particle duality, or non-locality, or the Pauli exclusion principle ?

Just because you have a chip on your shoulder about your educational experiences it does not mean that you are representative of the majority. Any fool can research websites for mavericks who will fuel their obsession. And if you think your hundreds of postings here are indicative of anything more than a neurosis, you have even less intelligence than I originally gave you credit for.

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@fresco,

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If you think SR is "problematic", how do you cope with wave-particle duality, or non-locality, or the Pauli exclusion principle ?

SR raises all kinds of problems for QM too. John Stuart Bell himself said that the simplest solution would probably be to simply revert to a lorentzian (AST) theory of relative motion.

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@FBM,

FBM, I said:

Quote:

What your frame "tells" you is not always what's really happening. Again, think travelling twin.

Your response was:

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Then knowledge is impossible and chaos ensues.

Why, in your opinion, is a (highly artificially and misleadingly defined in SR) "frame of reference" somehow the one and only criterion for knowledge and order?

If an astronaut who has been blasted off for the moon "actually thinks" that he, not the earth and moon, is the one moving, then he is saying that what his frame "tells" him (per SR, mind you, not per se---what your frame "tells" you depends on your theory of motion) is wrong.

Is HE wrong, when he says that, you think? Has HE suddenly lapsed into a state of ignorance and chaos?

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@layman,

Duh!
Of course, relativity raised objections to its rebellious offspring QM. So what !
You signally avoid the "reality" and "common sense" issues you milked to death in your diatribe. Are you trying to tell us that non-locality is more "logical" than equivalence of reference frames ? Pull the other one !

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@layman,

If an astronaut blast off from the moon and achieves a speed that matches the CMB, then who is moving, The moon or the astronaut?

No matter how you slice this, it always comes back to frame of reference and your insistence that your decision to only use one frame that you unilaterally decide is the only way to tell time. SR doesn't rely on you for frame of reference.

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@FBM,

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My clock doesn't tell me that I'm either losing or gaining time.

Of course not. How could it?

Nor does a "frame' tell you anything.

It is only your theory of relative motion (which itself may be right or wrong in terms of it's correspondence to what's "out there") that can "inform" you about that.

Clocks don't talk. Nor do frames of reference. It is only within the framework of a "working theory" that you can derive any meaning about what a clock, or a frame of reference, "says."

Definitions and tautologies can tell you nothing about physics (1.e., matter in motion). To simply DEFINE a "frame of reference" as being "absolutely motionless" does not, and can not, make it so.

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@parados,

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SR doesn't rely on you for frame of reference.

True. And, likewise, I don't rely on SR for a meaningful, consistent, conception of what a "frame of reference" is, or "tells" me.

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@parados,

What SR deceptively presents to you as "equivalent frames" quickly gets transformed, by way of verbal "sleight of hand." to frames that are DECIDEDLY UNEQUAL.

1. First SR tells you that, for purposes of doing experiments in a room where you are stripped of any extended use of your senses and of ALL external knowledge and information, "all frames are equivalent."

Fine, I have no problem with that. I agree completely.

2. Then SR tells you that, since frames are equivalent, it is perfectly "legitimate" to use any old frame you want, and there are, and can be, no "preferred" frames.

This is quite debatable, actually, but let's just say I agree, what now?

3. That means you are "entitled" to treat your own frame as being absolutely motionless.

Really? Why would THAT follow? But, lets say I agree. Now what.?

4. Here comes the switch: So since you are "entitled" to treat yourself as "motionless" we now say you MUST treat yourself (your frame of reference) as absolutely motionless (if it's inertial).

Can I treat it as "possibly" moving with respect to another object? Like, maybe just a little bit, like, say 10 mph while the other is doing maybe 1000 mph? NO!

Can I treat the other guy as being stationary, when there is relative motion between us? MOST DEFINITELY NOT!!

But I though all frames were "equivalent?" SR: Well, think again, Pal. Some frames are more "equivalent" than others. YOUR frame is always it's own "ether," completely motionless.

But isn't that what you would call a "preferred frame?" NO!! We NEVER call it that.

1 Reply

@layman,

You can only see (measure) things from your own frame of reference. The other frame can only see (measure) things from their frame of reference.

You keep insisting that all frames have to see (measure) things from the same reference. That is nonsense. It doesn't make all other frames wrong. It only means they see (measure) different from your frame.

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@parados,

Quote:

It doesn't make all other frames wrong. It only means they see (measure) different from your frame.

Of course not. But it doesn't prove that your frame is "right," in terms of ultimate "reality," either. It can be seen as "right" in terms of how it "measures" things, but you can always mismeasure--such as if you mistake a 1/2 cup for a full cup when "3 cups" are called for.

In as AST theory, for example, a person might justifiably assume that his own clocks and rods are accurate. And using them he definitely WILL find the speed of light to be c.

But that same theory would say that his measurement, though carefully and accurately made within that frame, could still be wrong. In fact such a theory would say that the person doing the measuring IS wrong, if he fails to take his own relative motion into account before arriving at his "final" conclusion.

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@layman,

Quote:

In fact such a theory would say that the person doing the measuring IS wrong, if he fails to take his own relative motion into account before arriving at his "final" conclusion

Note that this does NOT require an absolute rest frame, just as it did not require an absolute rest frame to determine that the travelling twin was the one really moving (and hence aging more slowly) in the twin paradox. It does, however, require one to resort to a "preferred" frame (which needn't be "absolute").

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@parados,

Likewise, a guy sitting on a jet plane travelling at 600 mph with a clock in his lap is quite free (if he is that stupid) to INSIST that he is not moving, and this his clock IS NOT slowing down, relatively to an earth clock.

He can likewise INSIST (and he can scream it at the top of his voice for all in the aircraft to hear) that Washington, D.C. (and only Washington, not him) is moving.

But, no matter how loud he screams, his clock will show less time elapsed when he lands and holds his clock up next to the Washington clock. According to SR, this proves that his clock was the one moving, not the one in Washington.

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Why in the world would Einstein suggest....

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