# Einstein got it all wrong?

Discussion in 'Physics & Math' started by scifes, Mar 26, 2011.

1. ### originTrump is the best argument against a democracy.Valued Senior Member

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How about this - lets hypothetically say that there is a space ship that instanteneously accelerated to c. Neglecting the rather high g forces involved, to the traveler in the space ship the universe would would shrink to zero distance perpendicular to the direction of travel.

Sorry still not sure what you are trying to say so lets try this - if a space ship were flying by at a 99% the speed of light it would look like a flying pancake because the length would contract realtive to the direction of travel. It would not be an illusion it would really be that length and if you had a really, really fast shutter speed on your camera you could measure that contracted length with a ruler as it flew by.

If you were flying in the space ship everything along your direction of travel would also be length contracted. If you were flying at 99% the speed of light then it would only take you about 1.7 months to travel a light year (by your clock) because the length is contracted.

I am not sure what this 'your and my reality' is all about...

Last edited: Apr 6, 2011

3. ### AlphaNumericFully ionizedModerator

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After Emil has finished with the "A lazy idiot's beginners guide to relativity" you can borrow it from him MD. Now run along and troll elsewhere.

5. ### EmilValued Senior Member

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If an object has a speed 99% of the speed of light and we calculate on the Earth without taking into account the Lorentz transformation,
it will pass to a distance of 5,000 km from the center the moon, so it will hit the moon.
You affirm that it will not hit the moon, because it "sees" the moon radius as being 900 km?

7. ### originTrump is the best argument against a democracy.Valued Senior Member

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Of course not. Length contraction occurs along the direction of travel, not normal to the direction of travel.

8. ### EmilValued Senior Member

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Yes, for the photon.
Yes, I wonder about that myself.

9. ### EmilValued Senior Member

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So, how many km it "sees" the moon radius?

10. ### originTrump is the best argument against a democracy.Valued Senior Member

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Flying towards the moon a 99% the speed of light the moon would have a diameter of 3476 km normal to your direction of travel.

The diameter of the moon for the axis parallel to the direction of travel would be approximately 485 km.

11. ### Motor Daddy☼☼☼☼☼☼☼☼☼☼☼Valued Senior Member

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Wrong. The moon's diameter isn't dependent on your velocity. You living a world of illusions doesn't change the diameter of the moon.

12. ### rpennerFully WiredStaff Member

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The moon has proper dimensions as it is a more-or-less solid body more-or-less at rest with respect to itself. It is close to spherical with a polar radius differing from the equatorial radius by about 1 part in 800. To this level of accuracy, it may be said to have a proper diameter.

The "visual diameter" is the angle the diameter of the moon makes by the observer and is a function of the position of the observer, and so is a red herring introduced by Motor Daddy. Especially since visual diameter is perpendicular to the direction connecting observer and object.

The term "specific diameter" is not defined.

Because of the moon's relative motion to the earth is on the order of $3.5 \times 10^{-6}$ c, any relativistic effect is far smaller than the 1 part in 800 by which the moon already differs from spherical in its own frame. At a relative speed of c/20 the speed of light, the moon would have a coordinate diameter in the direction of travel of about 799/800 of its proper diameter. This speed (33.5 million miles per hour) is far faster than any speed Motor Daddy has observed and still leads to insignificant effects, which is why we wholly discount Motor Daddy's preconceptions and bald assertions about what happens at faster speeds.

13. ### originTrump is the best argument against a democracy.Valued Senior Member

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Well like I said, your incredulity and inability to understand physics is not a very good reason for me to abandon science.

14. ### rpennerFully WiredStaff Member

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Your use of "significant" is unscientific, since the bulk of stellar distances are not known with a precision of 1 part in 10000. That's about the uncertainty of the gravitational constant. http://physics.nist.gov/cgi-bin/cuu/Value?bg

No body native to the solar system has an relative motion of 1.4% of the speed of light, so special relativity doesn't rise to the level of 0.01% corrections to Newtonian terms. Your claim rests on no relevant facts.

Indeed, I do know of examples
http://en.wikipedia.org/wiki/Relativistic_aberration
http://arxiv.org/abs/0901.3511
http://en.wikipedia.org/wiki/Aberration_of_light

Although most examples of really fast astronomical bodies come from GR (cosmology or black holes).
http://www.astro.ucla.edu/~wright/cosmoall.htm
Section 5 of http://relativity.livingreviews.org/Articles/lrr-2006-3/
But some come from the solar system, i.e. Mercury and the Moon.

15. ### Janus58Valued Senior Member

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If you stop, you will find yourself same relative position between Earth and Sun after stopping as you were before stopping.

For example, if you are traveling at 0.866c relative to the Earth and Sun, you will measure the distance between Earth and Sun to be ~75,000,000 Km).

If you when you have traveled 50,000,000 km, you will find yourself 2/3 of the way to the Sun. If you now stop. you will find yourself 100,000,000 km form the Earth and 50,000,000 km from the Sun, still 2/3 of the way from the Sun and Earth.

If instead you continue to travel until you are 50,000,000 km past the Sun and then stop, you will find yourself 100,000,000 km past the Sun after you stop.

Its not like you are going to travel 125,000,000, having past the Sun while traveling, then stop to find that you are 25,000,000 short of reaching the Sun. That's not how length contraction or Relativity works.

16. ### Janus58Valued Senior Member

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What does this have to do with what you quoted from my post, and where do I say that you can have a velocity relative to space?

17. ### Janus58Valued Senior Member

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How do you decide which frame is "moving" and which frame is "stationary". Are you trying to say that the rod is not length contracted because it is the spaceship that is "moving" and the rod isn't.

If so, this is in violation of the Principle of Relativity, which simply put, says that there can be no "preferred" reference frame that is considered as being at absolute rest.

18. ### Janus58Valued Senior Member

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I know you don't.[/quote]
I have my time or space unaltered. That is my "reality". Lorentz transformation is applied to the others, from my point of view. But I can not duplicate myself, so my reality is always the same.
You argued: Yes, this is your reality, but I have my own reality, because the Lorentz transformation. And everyone has their own reality based on relative speed.
Some of us declare that we have a unique shared Reality, and we make efforts to push the boundaries of knowledge of this unique Reality.
We live together in this unique Reality, while you live each in your own reality based on relative speed of each.So who lives in his own dream and who lives in a common dream that they called Reality.[/QUOTE]

Below are two pictures of Al Capone. Which one is "reality" and which one is just a "perception" or illusion?

19. ### rpennerFully WiredStaff Member

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Brilliant illustration of how rotation doesn't alter reality and yet is "real" and so therefore a hyperbolic rotation (Lorentz transform) doesn't alter events or causality but does really alter lengths and durations between world-lines and events, respectively.

20. ### EmilValued Senior Member

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In terms of Relativistic is as valid the following response:
the Moon does not change, the object shrinks to 7 times.

21. ### EmilValued Senior Member

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That is not .01%?
You know very well that I'm talking about SR and not about GR.

22. ### EmilValued Senior Member

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If you add that my watch shows 576.4 seconds after I stop in front of the Sun, then I recognize the answer.
I think I understand what you mean.
If you pull a rope between the Sun and Earth, then I can consider the Earth, Sun and the distance between them as an object so it can apply the Lorentz transformation and to the rope (the space between the Sun and Earth).That's it?

23. ### EmilValued Senior Member

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Yes illustration corresponds to what I say.
Whatever the look, we see Al Capone.(Al Capone is the reality)
If someone sees someone else means that he was wrong.