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Hi all,Is the Lorentz Contraction real or not real.What a beautiful 'can of warms' we got open here. We all want to find out the truth. If we come close to finding out the truth we will also find the answer to the question of this thread: Is angular momentum frame dependent?I suggest we all put aside our convictions what is the correct answer and we develop an argument together; we find the answer together.There are good points on both sides, to show that the LC is not real and also to show that the LC is real.First, let us discuss how we can show the LC is not real. I'll make a statement and I suggest we get an agreement if the statement can lead towards the answer.If we say yes, then we will analyze and prove the statement.If the Special Relativity is reciprocal then the Lorentz Contraction is not real.Please, let us discuss the statement above. Do we agree it is a true statement?Jano

Quote from: Jaaanosik on 01/08/2020 20:37:11If the Special Relativity is reciprocal then the Lorentz Contraction is not real.Please, let us discuss the statement above. Do we agree it is a true statement?JanoWhat do you mean by special relativity being "reciprocal"?

If the Special Relativity is reciprocal then the Lorentz Contraction is not real.Please, let us discuss the statement above. Do we agree it is a true statement?Jano

Both observers are correct and length contraction is real.

They cannot be both real because of the Twin paradox.

There are good points on both sides, to show that the LC is not real and also to show that the LC is real.First, let us discuss how we can show the LC is not real. I'll make a statement and I suggest we get an agreement if the statement can lead towards the answer.If we say yes, then we will analyze and prove the statement.If the Special Relativity is reciprocal then the Lorentz Contraction is not real.1) You'd have to show that SR is reciprocal in all cases, not just one. It isn't.2) I don't agree with your statement at all. SR could be completely reciprocal and LC could still be real.QuoteWhat do you mean by special relativity being "reciprocal"?Two inertial observers see each other clocks going slower.Two inertial observers see each other Lorentz Contracted.

What do you mean by special relativity being "reciprocal"?

Whatever the first inertial observer can say about the second one then the second observer can say the same things about the first one.

There is no preferred reference frame.

If the Special Relativity is reciprocal then the Lorentz Contraction is not real.Please, let us discuss the statement above. Do we agree it is a true statement?

Two inertial observers see each other clocks going slower.Two inertial observers see each other Lorentz Contracted.Whatever the first inertial observer can say about the second one then the second observer can say the same things about the first one.

This is the definition of reciprocal in my view.Do we have an agreement?

passing a virtual baton to each other when they pass each other.

Quote from: Jaaanosik on 02/08/2020 18:19:29This is the definition of reciprocal in my view.Do we have an agreement?No, we do not. Your diagram doesn’t make sense, nor does it define reciprocal.

No, it is not reciprocal. We can see this in a case where one clock travels round and round in circles with another clock in the centre of the circle. Let's say that these clocks are in spaceships with the circling one always moving at 0.866c relative to the central one. If they are transmitting video to each other, the crew of the central ship will see the people in the other ship living in slow motion, and their clock will confirm it, ticking half as often as the central ship's clock. However, in the circling ship, when they watch the video coming from the central ship, they see the people in it moving about very fast, and they see that the clock there is ticking at twice the rate of their own clock. So it is not symmetrical.How do defenders of STR deal with this? They assert that STR can't handle it because of the involvement of acceleration and that you have to switch to GTR, but that's a bogus argument. You can eliminate the accelerations by having lots of other clocks moving at 0.866c along tangents to the circle make timings of the almost exactly the same course by acting as a relay team, passing a virtual baton to each other when they pass each other. Here's an animation of it magicschoolbook.com/science/STR-disproof-5.html to help you visualise it correctly. These clocks moving along tangents to the curve tick at the same rate as the circling clock while they accompany it during their leg of the relay. No matter which frame of reference you use to analyse this, you determine that the clocks moving along tangents are ticking on average at half the rate of the central clock. That is not symmetrical. There are certainly some clocks in there that are not accelerating at any point which are ticking slower than the central clock, even though there is no possible mechanism in STR to allow them to do so.

Quote from: David Cooper on 03/08/2020 01:00:06passing a virtual baton to each other when they pass each other.The act of "passing the baton" will require acceleration, because the direction that the mass-energy aboard the ship is moving will change every time a signal (which must be composed of that same mass-energy) is passed from one ship to the other.

David was commenting that there exist scenarios where relativity is not reciprocal. I agree with him on that point. He incorrectly asserts that SR cannot handle acceleration, but is gravity that SR cannot handle.You simply presented one example that was reciprocal according to your definition, but it isn't always the case as evidenced by David's counter-example and several other counter-examples in the other thread.Length contraction being real or not does not hinge on this reciprocal property, so I don't know what you think has been illustrated by it all. I thought M-L had a better definition: It is real if there is a real consequence that all observers can agree on, such as one twin being older than another.