Questions of theory of relativity

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Questions of theory of relativity

Postby Guoxin » Thu May 03, 2007 8:28 am

For the train paradox, assuming the person traveling in the train at a speed of light does not disintergrate. Why the person experience a different time to everybody outside the train? Why the time in the train seemed slower? Why do the person in the train wont age as fast? Traveling at the speed of light is just a matter of traveling faster then everyone else , it does not mean the time dimension becomes warped for within or outside the train. Isnt time a linear dimension in that sense?, everyone experience the same time all the time. What it mean by everything seemed slower?...... u may think its slower.....but the cells in ur body will produce and die at the same rate in time, u will age the same.
I dont understand how relativity time comes into play in this case. It happens to velocity but not to time???? I dont really see the paradox.

Another thing is about why many believe that what einstein say that speed of light is the fastest thing in the universe. Because of that , he state that gravitation force is not instant, thus saying newton is wrong. I do not think einstein can be really sure of that, he still have to make this BIG assumption that light is the fastest thing we can imagine. Even if light travels the fastest in this universe, but light is photons traveling, its SOMETHING traveling. Do people know what exactly is gravitation force made of? Yes we know the Law....mass attracts mass.....what is the force made of? it may not be a physical thing itself. So how can u compare light and gravity. Although i respect einstein because he fuelled human's desire to search for the truth, but in my opinion he not correct in alot of things.

Einstien is not open to the idea of quantum physics if im not wrong. Why?
isnt science about having a open mind about all thinkings. And also theres just a overload of info in the science world like string theories, or the field of astronomy that i really dunno what is true or whether these thoeries are based on core theory after theory. Wouldnt all "after" theories becomes void when someday the core theory is proven wrong? I dunno u guys but i really hope we really know wat we are doing and really support some of the claims. U know humans are creatures that can imagine alot of things, maybe we are just imagining all these.

Im open to all criticism. I may not be the wisest around but i really wanna understand more about this. Pls enlighten me. Thks.
Are we going to find the Unification of all theories? Theory of Everything?
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Postby houserichichi » Sun May 13, 2007 4:48 am

There really isn't an answer to your "why" question regarding the time dilation. It's just the way the maths of special relativity pan out. As velocity increases so does the passage of time decrease in one's frame of reference.

Image

In this picture the little * is the particle that bounces between the plates on a moving spaceship thing which we'll pretend is a train. To the man on the train it looks like the * is moving straight up and down because he doesn't have any windows and can't tell he's moving. Let's call each bounce up and down a full second. Now to the man on the ground (not the spaceship) it would appear as though the * is moving in a diagonal-up direction toward the plate at the top and then back diagonally downward (diagonally forward, following the dotted line) since the train (and hence the plates) is moving forward. Pythagoras tells us that the distance (length of time it takes) between the second case is longer than that of the first case. Thus time dilation.

No the cells in your body will not live and die at the same rate. Things really do go slower and has been shown evident by a great many time dilation experiments that fall completely in line with special relativity. This is why relativity is so "counterintuitive" because it's not the way we know the world to work.

Einstein didn't quantify gravity. A photon is the quantum of electromagnetism (one of the four forces of nature). The graviton (assuming one even exists) would be the quantum of gravity. The photon travels at the speed of light because it is massless and the mathematics of particle physics requires that all massless particles travel at light speed. As it turns out the graviton has never been experimentally found but so much theoretical work has been done on it that physicists are certain that should the graviton exist it would be massless as well, thus it would also travel at light speed.

The bit about Newton being wrong is technically true but the deviations from Newtonian physics at everyday speeds (like driving a car or walking on a sidewalk) are so small that they might as well be thrown away. Newton is right up to a very good approximation at "normal" human speeds but when things get crazy (like in particle accelerators and black holes, for instance) Newton gets thrown out the window because things get very fast. Newtonian physics is good for "slower than light" speeds.

Einstein didn't like quantum mechanics because of its dependence on probability. He is quoted as saying something to the extent of "God does not play dice" meaning that Einstein viewed the universe in absolutes with no room for probability or chance. Einstein made a great breakthrough for the field but just because he didn't like QM doesn't mean he was a poor judge or representative of the field. Just because Einstein didn't believe something also doesn't make it untrue. He was great but he certainly wasn't a deity.

As for the bit about theories being built upon theories being built upon theories...if the foundation cracks then the whole thing comes tumbling down. Absolutely that's the case unless, of course, the foundation isn't shattered but just built upon. The perfect example is something you already mentioned. Newton wasn't wrong. He was the foundation for a huge branch of physics which relativity "replaced". Don't think of Newton as being wrong and things come tumbling down...think of Einstein's relativity as a lower level to the tower of theories. We thought Newton was the bottom floor but Einstein found a secret door with stairs down to a basement...relativity was a floor lower. There are still floors lower than special relativity but they're all up for debate and scrutiny.

It's the same thing as in any science, though. If a theory is proven absolutely incorrect (ie: me claiming that time and space are completely separate entities) then anything built upon it will crumble. That's not to say the core ideas can't be salvaged and turned into something new and possibly better, but the tower of knowledge that was initially however high must necessarily be rebuilt/abandoned for when the foundation collapses so does the theory above.

The great piece about science is that towers are build and crumbled all the time. That's why it's such a positive field to get into...options are open to any and all to make some sort of contribution. Some get lucky and build whole new towers, some get lucky and crumble whole ones. Some get unlucky and have their life's work crumble....but them's the breaks.

Good post, I enjoyed your thoughts.
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