Why in the world would Einstein suggest... 2

@layman,

No, i don't see the significance of that. Care to explain what you're thinking of?

@Olivier5,

Quote:

No, i don't see the significance of that. Care to explain what you're thinking of?

Well, let's take it one step at a time. With respect to the following quote:

Quote:

It's often said that special relativity is based on two postulates: that all inertial frames are of equal validity, and that light travels at the same speed in all inertial frames. But in real world scenarios, objects almost never travel at constant velocity, and so we might never find an inertial frame in which such an object is at rest.

1. Is there anything you don't understand about it?
2. If you understand, do you agree?
3. If you agree, is there any significance to what's being said?

1 Reply

@layman,

That's something I've been saying here forever. Glad you paid attention... The point which relevance seems minor to me was the observation that acceleration in and by itself does not impact time dilatation.

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@Olivier5,

Quote:

That's something I've been saying here forever. Glad you paid attention

Yes, indeed, you have been saying that here forever. Many, many, many, many times.

Quote:

The point which relevance seems minor to me was the observation that acceleration in and by itself does not impact time dilatation

Does this point "seem minor" to you in connection with what you been saying forever?:

Quote:

To allow us to make predictions about how accelerating objects behave, we need to introduce a third postulate. This is often called the "clock postulate"...clock postulate says that the rate of an accelerated clock doesn't depend on its acceleration...The clock rate won't be affected by circular motion at constant speed....

1 Reply

@layman,

Whatever.

1 Reply

@Olivier5,

If you had ever read it, you might recall that Einstein, in his original 1905 paper, said that a clock at the north pole would run faster than a clock on the equator. Why? Because the clock on the equator is moving in a circle at a constant rate, whereas the other is not. It is, after all, the (faster) moving clock that runs slow.

He did NOT say: "My theory has nothing to say, and certainly no predictions to make, about those two clocks, because they are not in an inertial frame."

That's why wiki says:

Quote:

The clock hypothesis was implicitly (but not explicitly) included in Einstein's original 1905 formulation of special relativity. Since then, it has become a standard assumption and is usually included in the axioms of special relativity...

Another way of looking at it is that it only relative SPEED, not relative velocity, which causes the resulting time dilation. You can ignore changes of direction.

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@Olivier5,

Quote:

Whatever

Am I to take that as a statement that you now see the significance of the clock hypothesis?.

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@layman,

Quote:

If you had ever read it, you might recall that Einstein, in his original 1905 paper, said that a clock at the north pole would run faster than a clock on the equator. Why? Because the clock on the equator is moving in a circle at a constant rate, whereas the other is not. It is, after all, the (faster) moving clock that runs slow.

It is also worth noting that Einstein here posits an absolute difference between the clocks, and presumes to know WHICH one is ACTUALLY MOVING (relative to the other).

These days, the relativists like to pretend that such things are "unknowable." Go figure, eh?

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@layman,

Quote:

He did NOT say: "My theory has nothing to say, and certainly no predictions to make, about those two clocks, because they are not in an inertial frame."

How could a physical object like a clock possibly be IN a mathematical object like a frame of reference? It's like saying "these two physical elephants here are not in Beethoven's 9th symphony." You should think this stuff a bit deeper, lay. Now you're just making a joke of yourself.

1 Reply

@Olivier5,

OK.

Are you going to answer my question?:

Quote:

Am I to take that as a statement that you now see the significance of the clock hypothesis?.

Or are you through commenting on that topic?

1 Reply

@layman,

As I see it, it's a computation shortcut based not on the theory, but on observation. It has no theoretical importance that I am aware of. But then I don't know everything...

1 Reply

@Olivier5,

Quote:

It has no theoretical importance that I am aware of. But then I don't know everything...

Whatever else you may or may not know, you clearly don't know how "important" a hypothesis is to a "theory." This is presented as a necessary 3RD "postulate" or "axiom." Just so you know, these types of things are ABSOLUTELY FUNDAMENTAL AND INDISPENSABLE to any "theory." That means they are of "theoretical importance," get it?

Quote:

As I see it, it's a computation shortcut based not on the theory

Of course it's not "based on" the theory. It can't be. Being a postulate, it IS the theory.

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@layman,

layman wrote:

Quote:
...neither a train nor the earth surface can reasonably be considered inertial.

Why not? You claim to know, understand, and subscribe to SR, don't you? Are you suggesting that you have somehow discovered a way, in contradiction to all the tenets of SR, to determine that the earth is accelerating (or otherwise moving) through absolute space?

I'm not trying to solicit an answer from you, by the way. Just a rhetorical kinda question, to myself, really. ...

We've been there several times already. You lack the conceptual tools necessary to understand the answer. Eg you keep confusing objects and frames.

Also, you used the term "absolute space". What's that? A preferred aether-based frame of reference? Where is it? Where is this aether? Even your preferred theory (LET) says it's undetectable... One difference between LET and SR is that in SR aether is treated as non-existent, as any non-necessary hypothesis should be according to Ockham and indeed Poincaré himself. One full century after this debate, no aether has ever been found, even with the most modern tools...

Another essential difference between Lorentz and Einstein lies in their interpretation of length contraction: for Lorentz it was a physical contraction of atoms and molecules in the direction of movement. For Einstein it's about space itself being contracted... Now, if it was a molecular effect, you'd think some compounds would be more resistant to it than others, but no such thing has been found.

Meanwhile, countless observations have been made that are consistent with SR and GR. We've discovered black holes thanks to their theoretical possibility in GR, etc. Propping up Lorentz at this late hour seems anachronic.

1 Reply

@layman,

Yes, but more importantly, i like the idea that this spacetime diagram corresponds with our own innate intuition about time.

1 Reply

@Olivier5,

All that, and you don't answer the simple question of "why not?"

Quote:

One difference between LET and SR is that in SR aether is treated as non-existent, as any non-necessary hypothesis should be according to Ockham and indeed Poincaré himself. One full century after this debate, no aether has ever been found, even with the most modern tools...

Time after time after time you prove that you do not understand the "significance" of what is said to you. Or maybe you just don't understand it, period.

1. I have repeatedly given you authority which says, and I have in addition repeatedly pointed out to you that I have given you, the "news" (for you, that is) that the ether hypothesis is NOT a necessary element of LR. Yet you never "see the significance," do you?

2. As I have also pointed out (and have quoted several prominent phyiscists (including nobel prize winners to show) that the CMB is currently being treated by astrophysicists as what one called "the rest frame of the cosmos" (with apologies to Al, of course). It is NOT the ether. But it does provide a frame which has been shown to homogenously fill the universe to an accuracy degree of at least one part in 100,000.

Quote:

propping up Lorentz at this late hour seems anachronic

.

You seem to be a little behind the times on your grasp of modern physics eh? LR is used day in, day out, by astronomers, astrophysicists, the global positioning system, etc. on a mass scale these days.

Quote:

Meanwhile, countless observations have been made that are consistent with SR and GR.

Great, and as you have been told by experts (whose comments were produced by me) every such observation is ALSO consistent with LR. Are you now suggesting otherwise?

1 Reply

@Olivier5,

Quote:

this spacetime diagram corresponds with our own innate intuition about time.

That's kinda strange. Just yesterday you were (parroting what you heard from Poincare, no doubt) announcing that simultaneity is not an intuitive notion. I guess you forget that Poincare also said that TIME is NOT an intuitive notion, and that simultaneity depends on time.

Quote:

Why clinch on simultaneity? It's not even an intuitive notion

Those minkowski diagrams you are now so found of also have a "line of simultaneity," don't they? More innate intuition with that, I suppose?

1 Reply

@layman,

Quote:

All that, and you don't answer the simple question of "why not?"

That question has been answered many many times already. You are amazingly obtuse.

1 Reply

@layman,

That diagram does not speak of simultaneity, and Poincare never said that time was not intuitive. On the contrary, he says in the opening statements of that chapter ("The Measure of Time") that psychological time is a given, and non-problematic. How obtuse can you be?

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@Olivier5,

Quote:

That question has been answered many many times already

Great, then it should be easy to refer me to one of your many, many answers, eh? Or simply succinctly restate it. Indulge me, eh?

To refresh your memory, the issue arose when you said:

Quote:

...neither a train nor the earth surface can reasonably be considered inertial.

I then asked: Why not? In what way are they both accelerating, and how do you know that?

1 Reply

@layman,

If you haven't understood my wording before, why would you understand it now? Some people just can't understand some stuff. That stuff is beyond you, period.

1 Reply

Why in the world would Einstein suggest... 2

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