TRAVELLING TWINS

@Olivier5,

From the link:

"Draining in bathtubs and toilets.
Contrary to popular misconception, water rotation in home bathrooms under normal circumstances is not related to the Coriolis effect or to the rotation of the earth, and no consistent difference in rotation direction between toilet drainage in the Northern and Southern Hemispheres can be observed."

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@maxdancona,

Quote:

The effect has also been measured in the laboratory (where there are two identical particles and one experiences more "time" than the other).

You talk about what happens "in the lab" in a way that suggests that the mathematical caculations somehow "correspond to reality." For example, you go on to say;

Quote:

The math works and laboratory experiments with particles confirm that it is correct.

Here claiming that the "math is correct" clearly is intended to go beyond math itself and suggest something like "the math corresponds to objective physical reality."

Elsewhere you (quite correctly) explicitly qualify some of your claims as "mathematical" claims, for example"

Quote:

But mathematically speaking, a twin can (and quite often does) have a zero velocity.

Yet overall, you seem to believe that an "understanding" of SR merely comes down to an understanding of math. But math is NOT physics, and does not necessarily have the slightest thing to say about physical reality. As Einstein himself acknowledged:

Quote:

As far as the laws of mathematics refer to reality, they are not certain; and as far as they are certain, they do not refer to reality.

http://www-history.mcs.st-and.ac.uk/Extras/Einstein_geometry.html

Any attempt to reduce questions about how SR relates to physical reality to questions about math is seriously misguided.

1 Reply

@maxdancona,

Quote:

The wikipedia article does a pretty good job providing a layman's explanation. Because one particle undergoes acceleration and the other one doesn't we are talking about more than one inertial frame. There is no symmetry.

There is no contradiction here. The math works and laboratory experiments with particles confirm that it is correct

.

Here is more of the same, but here you step outside math to claim: " There is no contradiction here."

That's why I asked you this:

Quote:

No contradiction between what and what else? What "contradiction" would you even be talking about?

No response, of course. Do you even know what "contradiction" is typically asserted in connection with the "twin paradox?" Once again, a hint: It is NOT a mathematical contradiction.

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@maxdancona,

Quote:

The wikipedia article does a pretty good job providing a layman's explanation. Because one particle undergoes acceleration and the other one doesn't we are talking about more than one inertial frame. There is no symmetry. There is no contradiction here

I disagree with this. Insofar as the wiki article uses (which it may not, I haven't read it lately) such obscure "explananatory" terminology as "no symmetry" and "more than one inertial frame," it is NOT a good explanation for the layman. There is, however, a reason for such obscurantist tactics (which I will come back to).

Of course there is no contradiction in the math. The theory clearly predicts that the moving clock will run slow. Physicists like Feynman, who don't have an ulterior agenda to serve, state it very plainly (for the layman):

Quote:

"Just as the mu-mesons last longer when they are moving, so also will Paul last longer when he is moving. This is called a "paradox" only by the people who believe that the principle of relativity means that all motion is relative.... the one who comes back must be the man who was moving, and he knows this, because he had to turn around..that is the difference between them in an "absolute"sense, and it is certainly correct. (Lectures on Physics)

Of course there is no symmetry. One is moving, one isn't (relatively speaking). The theory SAYS the moving clock is the one that runs slow, so this is merely fulfilling the predictions of the theory. That's not where the "paradox" lies. "Changing frames of reference" has nothing to do with it, either, per se, and is just used as a way of avoiding saying the space twin was the one moving.

Why don't SR apologists want to give this simple and accurate explanation to laymen? There is a reason. What is it?

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@layman,

I said:

Quote:

But math is NOT physics, and does not necessarily have the slightest thing to say about physical reality. As Einstein himself acknowledged:..Any attempt to reduce questions about how SR relates to physical reality to questions about math is seriously misguided.

Tim Maudlin (among many others) has made some comments along the same lines (although he was ostensibly contrasting physics and philosophy, not physics and math, per se):

Quote:

Many questions about the nature of reality cannot be properly pursued without contemporary physics. Inquiry into the fundamental structure of space, time and matter must take account of the theory of relativity and quantum theory. Philosophers accept this. In fact, several leading philosophers of physics hold doctorates in physics. Yet they chose to affiliate with philosophy departments rather than physics departments because so many physicists strongly discourage questions about the nature of reality. The reigning attitude in physics has been “shut up and calculate”: solve the equations, and do not ask questions about what they mean....

But putting computation ahead of conceptual clarity can lead to confusion...If your goal is only to calculate, this might be sufficient. But understanding existing theories and formulating new ones requires more.

This is why, Max, when you want to ask how many have taken physics courses, it is only fair to ask you how many courses in philosophy, especially the philosophy of science, that you have taken.

In case you don't know who Tim Maudin is:

Quote:

Tim Maudlin is Professor of Philosophy at New York University. He received his B. A. in Physics and Philosophy from Yale and his Ph.D. in History and Philosophy of Science from the University of Pittsburgh. His work centers on the interpretation of physical theory: how the mathematical structures used in physics may be understood as presenting a physical account of the world. His most recent books are "Philosophy of Physics: Space and Time" and "New Foundations for Physical Geometry."

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@usery,

My mistake, although i'm gona test that in my sink right now... :-)

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@maxdancona,

Quote:

The wikipedia article does a pretty good job providing a layman's explanation....There is no contradiction here.

I have asked you what conceivable "contradiction" you had in mind. Put another way, why is there any reference to a "paradox" (which entails the existence of some apparent contradiction) to begin with? You don't answer, so I'm going to assume you can't or won't answer.

However, since you explicitly made reference to the wiki article, I will make this comment on your claim. Wiki says:

Quote:

The paradoxical aspect of the twins' situation arises from the fact that at any given moment the travelling twin's clock is running slow in the earthbound twin's inertial frame, but equally the earthbound twin's clock is running slow in the travelling twin's inertial frame.

If the suggestion here is supposed to be that the paradox (contradiction) is that each "sees" the other's clock as running slow, then the alleged "paradox" (contradiction) has been misstated by the wiki author. That is not a paradox to begin with, so, if that were it, there would be no paradox to "resolve." There simply would be no "twin paradox" if that were all there is to it.

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