Does My Wrist Watch Physically Beat Slower?

[PeterDonis]

Prior to the paragraph. It is said that "That is, while the man measures the light from the front getting to the woman before the light from the back, the woman sees the light from both sides simultaneously.".

Please read more carefully. The statement in quotes is a *hypothetical*, which the author later shows to be false. He is *not* stating it as an actual conclusion of relativity.

[Edit: The same is true of the statement I said was incorrect: "in the woman's frame it will not since in her frame the flashes meet by her and not at point P"--it is also part of the hypothetical, which the author later shows to be false.]

 

[Tomahoc]

Please read more carefully. The statement in quotes is a *hypothetical*, which the author later shows to be false. He is *not* stating it as an actual conclusion of relativity.

[Edit: The same is true of the statement I said was incorrect: "in the woman's frame it will not since in her frame the flashes meet by her and not at point P"--it is also part of the hypothetical, which the author later shows to be false.]

Ok. I'll look into them. For now. I'm looking for web sites that illustrates what you mentioned that "If tachyons are allowed, then there are still going to be causally connected events that are spacelike separated. It doesn't matter that not *all* causally connected events are spacelike separated; having *any* of them be so is enough.".

Know any such website with spacetime diagrams of tachyons and effects on causality to get me busy this weekend.

Or maybe an actual example you already knew. If the baseball is made up of normal matter and throws into a windows. If no tachyons, there is no frames where the order is reverse? If there are tachyons flying alongside.. how come it can be reverse? I get the essence, but want exact details of how the worldline details work that can make the ordering reverse or chaotic. Thanks.

 

[PeterDonis]

For now. I'm looking for web sites that illustrates what you mentioned that "If tachyons are allowed, then there are still going to be causally connected events that are spacelike separated.

This follows from the definition of tachyons: they travel faster than light. That means they travel on spacelike worldlines, so successive events on a tachyon's worldline are spacelike separated.

If the baseball is made up of normal matter and throws into a windows. If no tachyons, there is no frames where the order is reverse?

If the baseball is made of normal matter, then it travels on a timelike worldline. The time ordering of events on a timelike worldline is frame invariant. (The same is true of the ordering of events on a lightlike worldline, so a "baseball" made of photons would be the same in this respect as a baseball made of normal matter.)

If there are tachyons flying alongside.. how come it can be reverse?

Please read carefully. I didn't say "a baseball with tachyons flying alongside it"; I said "a baseball *made of* tachyons". That means the baseball itself is moving faster than light.

I get the essence, but want exact details of how the worldline details work that can make the ordering reverse or chaotic. Thanks.

See above. The time ordering of events on a spacelike curve is frame-dependent. That's just a basic fact about spacelike curves.

 

[Tomahoc]

Adding tachyons doesn't change the fact that the time ordering of spacelike separated events is not frame invariant.



Allowing spacelike separated events to be causally connected would force us to modify all of the theories we have (which, as I said, is a lot of them) that assume that the time ordering of causally connected events must be frame invariant.

To see how drastic this would be, consider a commonplace causal phenomenon: I throw a baseball that breaks a window. If the baseball were made of tachyons, then in some frames those events would be in reverse order: to observers at rest in such frame, it would look like the window spontaneously reassembled itself as the baseball moved through it towards my hand.

Ah. As long as closed causal loop is solved by tachyons moving fixed in aether frame. There is no problem about reverse order. I mean. When you rewind your video tape or fast forward them. It is just in the function. One knows that window doesn't spontaneously reassemble. So if a frame shows that. We can say "Ah, it's just an artifact"... unless you want to argue that what happens in a frame actually happens such that the window spontaneously reassemble? But then we can just say to ignore it... and just treat the normal ordering as actual with the reverse order virtual like virtual particles.. just an artifact effect.

 

[Dale]

Given the assumptions you've been making, your logic seems valid.

Good, I am glad that you agree with that much at least.

While my intuition tells me that too much significance is given to the Lorentz ether theory

Honestly, I don't place any significance on LET, it is merely the most well-known counter example to the Vandam's false claim that the experimental evidence we have to date can only be interpreted as a block universe and not as any other interpretation as well as his other false claim that the relativity of simultaneity implies a block universe.

I can understand how he would be so tenacious in discounting LET (remember his citing Lorentz's own resignation)

Lorentz's disavowal of LET is historical trivia and not relevant to the question of whether or not the evidence supports it. Science isn't a popularity contest, the only vote that counts is nature's.

I'm not sure that the search for an experimental program yielding the distinction has been fully explored.

If you wish to continue the search then this is where you need to focus your efforts. The task is fairly clear: find an experiment where LET predicts X and block-universe predicts Y with X≠Y. I don't believe the task is possible, for the reasons stated above, but at least it is clear.

What you can say that is not overstepping is that the evidence is consistent with a 4D universe. You can also talk about the many aesthetic, practical, and philosophical advantages of the block-universe approach over other approaches, like LET. If you don't claim that the block universe is the only interpretation supported by the evidence then your drawings and explanations would be quite beneficial, I think. And there is certainly nothing wrong with simply stating that it is your clear personal preference.

 

[PeterDonis]

One knows that window doesn't spontaneously reassemble.

But how do we know that? Because we always see the events in the same order: throw baseball, then window breaks. If baseballs made of tachyons were commonly observed, and we commonly saw the events in the opposite order, we might not be so confident that we knew which order was the "right" one.

unless you want to argue that what happens in a frame actually happens such that the window spontaneously reassemble?

Part of the standard physical interpretation of a frame is that "what happens in a frame actually happens", yes. There is no room in the standard interpretation for some observations made in a frame to be "artifacts".

and just treat the normal ordering as actual with the reverse order virtual like virtual particles

Since you mention virtual particles, it's worth bringing up the point that if we include quantum mechanics, we can no longer say that tachyons can actually transmit information or causal influences faster than light. See here:

http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/tachyons.html

The same is actually true of virtual particles: virtual particles in quantum field theory can travel faster than light, but they can't be used to transmit information or causal influences faster than light, for the same sorts of reasons as tachyons can't be used that way as explained in the article above.

 

[jk22]

I think there are experiments checking the constancy of the speed of light no matter what the motion of the observer is in the so called emission theory (see Wikipedia), for example by measuring the speed of sun light during spring and autumn or from binary star systems and no significant difference could be found.
Another way to test it is the Sagnac interferometer that uses rotating mirrors.