Einstein wrong? Sure, about many things… did someone say “Cosmological Constant”? Also, have you ever read any of his books? He constantly uses the word ‘relatively’ when he means ‘relative’… There are some other grammatical faux pas, as well… But to say the Theory of Relativity is wrong is a bit extreme; it’s probably better to say that it’s just incomplete. But then I’m betting $100 that whatever theory finally replaces/supplements it will also be deemed to be incomplete within a coupl’a hundred years, as well… Science is a moving target.
As to time dialation, I think Brian Green had the best intuitive proof that it must occur, that I’ve seen. To believe the proof, you must accept that the speed of light is a constant in whatever medium you choose. Now imagine a clock that is constructed of two perfectly reflecting, opposing mirrors, oriented horizontally and in parallel. Let’s get a photon bouncing between these mirrors in a perfectly vertical way (i.e. there’s no Y component to it’s vector). Since the photon travels at a constant speed, the time from bottom mirror to top mirror and back to bottom mirror is constant. Let’s call that one tick. Now let’s introduce a couple of observers. One of them is standing on the bottom mirror (hey, it’s a big mirror). The other one is standing at some fixed point that I’m going to call the origin. Both observers perceive one tick to be the same. Now let’s set the mirror array, with our first observer in motion. At first the speed is fairly slow and both observers perception of one tick still looks pretty much the same. Let’s accelerate the mirror array and our first observer so that they are now moving at half the speed of light. The observer standing on the mirror sees what he always saw. The photon bounces exactly the same distance from bottom mirror to top mirror and the photon is still traveling at C, so one tick still equals one tick, right? Well, before we answer that, let’s look at the clock from the perspective of the observer at the origin. Now instead of a photon bouncing in a perpendicular line between two mirrors, he sees the photon painting a sawtooth pattern in a plane. The photon now has to cover more distance than before because it has X and Y components in it’s vector and the X component hasn’t changed. Since the photon still travels at C, one tick is now slower than it used to be from the perspective of the observer at the origin. Ergo, time has dialated for our observer at the mirror array - he just hasn’t realized it yet.
Hope this all makes sense and hope I didn’t leave anything critical out. I’m recounting Green’s example from memory, not verbatim. There are some other subtle points that I’ve intentionally left out, but I’ll wait and see if I draw any fire before I fill in the gaps.
If there is a speed greater than the speed of light, such as gravity, the theory of relativity would not be overturned. Simply replace the speed of light with the new maximum speed. There can be no such thing as determining synchronicity of events unless there is an infinitly fast “instantaneous” signal speed.
Special Relativity is certainly true, at least within the limits that make it “special”.
General Relativity is a little more iffy. Something a whole lot like it is certainly true, but there are still details awaiting confirmation, and rival theories that are similar, but not identical. Most people are betting on Einstein, though.
There is a problem, however, in mixing relativity with quantum theory. Somewhere in the middle there’s a new theory we don’t have yet.
As to the whole speed of light thing – here’s the problem. It is a fact, measured over and over and over again, that no matter how fast you’re chasing light, it’s always going exactly C faster than you are. That means that if two people are both chasing the same light, but at different speeds, it’s going at exactly C faster than both of them.
“But,” you say, “that’s ridiculous; it can’t be going at two speeds at once.”
Yup. It’s ridiculous. But it’s true anyway.
Special Relativity is just the math showing how the universe has to work, given that this totally wacky fact is true.
John W. Kennedy
“Compact is becoming contract; man only earns and pays.”
– Charles Williams
Of course, real scientists don’t like working with people. The twin paradox can be made non-personal. Think of a worm-hole (just do it) that’s is in such a shape that its entrance and exit are maybe 2 metres apart, and facing each other. One mouth (entrace/exit) will be slightly ahead of the other in time. So one mouth may be, say, five seconds ahead of the other (We can now say one has time 0 and one has time +5). If a billiard ball is rolled into into the one with time 0, it will come out the other mouth five seconds later. Say it takes 10 seconds for the ball to role in to the mouth; therefore, the whole process is complete in 15 seconds.
We need to assume that the ball gains velocity while on its 5 second trip through the wormhole. Now, roll a ball into the one that is time +5. The ball will come out of the mouth that is time=0, so it will go back in time five seconds, basically. This means, that there will be two balls (the same ball, two copies) at the same time. This is because the first ball went through in five seconds and then came out in the past; this was only half-way through its original ten second trip into the t=0 mouth.
If the ball is rolled into the t=+5 mouth, and it has the correct direction, and it gains velocity, can’t the ball hit itself in the past in such a way that it never enters the t=+5 mouth? This would mean that the ball would never enter the wormhole in the first place, but then how could it hit itself?
Sorry if I messed up, read this in a fascinating Hawking bio.
Studi
When I grow up, I want to be the Minister of Silly Walks.
An old saying among Air Force bomber pilots: “You get the most flak when you’re directly over the target.”
And
Self-introduction of a first-timer in the sci.physics.relativity newsgroup: “Let me start out with the standard disclaimer…I am an idiot, I know almost nothing, I haven’t taken calculus, I don’t work for NASA, and I am one-quarter Bulgarian sheep dog. With that out of the way, I have several stupid questions…” Alex Wagner.
I don’t know why.
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Ah…crap. I forgot to include a space after the URL. Sorry. I hope that is still readable. (Sure would be nice to have a preview feature…I think I’m going to add that to my sig.)
The Copenhagen interpretation is itself mostly intuition. One can go a long ways with intuition, but–as you mention Einstein did–you eventually run into facts. Einstein’s intuition has not been completely discounted, but that should be of almost unscientific interest anyway.
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reading the article, little “kook” buzzers sounded in my head when I saw that he thanked sci.physics, and of course, did not publish in anything that looked respectable to me.
Searching in sci.physics, it became clear everyone there thinks he’s a nut. Do a search in deja.com. Basically, his misconception is to believe the “gravity” and “gravity waves” are the same, and they are in fact not. Gravity is what holds you to the ground, but gravity waves are different, and could transmit information.
Flander’s seems to play fast and loose with
different theories. When he says a delay in
gravitation would be detected in orbits,
he is using Newtonian equations (old, outdated), not General Relativity equations. In actuality, the force depends on velocity as well as position, and so really the force is not quite central.
(these arguments taken from the link below…)
There have been lots of suggestions. None have panned out.
I’ve seen that article before. It is indeed well-written and seems plausible. However, IMHO the arguments boil down to arm-waving. I don’t know why the editors accepted it for publication. He’s trying to analyze using a mixture of Newtonian Mechanics and Special Relativity, and they don’t blend.
The sort of discussion that he presents is useful for visualizations and discussions, but for the real answers you gotta do the math.
Briefly, it is not correct to analyze gravitational interactions by Special Relativity with force vectors. In many cases, you can reasonably approximate the interaction by force vectors. When you do, you find that the force vectors do not point in the same direction as the Newtonian force vectors, and it happens that the propagation of gravity at the speed of light and the change in direction of the force vectors exactly cancel. This means that the Newtonian analysis (which does require infinite propagation speed for gravity) gives the correct answers in all but the extreme situations. It does {i]not* mean that gravity actually propagates at a speed faster than “c”. See Does Gravity Travel at the Speed of Light?.
The uncertainty principle is not more fundamental than the Copenhagen Interpretation, nor is it a foundation of quantum electrodymics. It is one of the milestones along the path of the development of the theory. However, it is possible to formulate and interpret quantum electrodynamics without any reference to an uncertainty principle. I seem to recall Feynman explaining this in his inimitable fashion, but I can’t remember where.
But that does not mean that relativity is incorrect. It’s just incomplete. Newtonian mechanics is correct … except in high gravitational fields or when velocities are a significant fraction of the speed of light. Just as relativity replaced Newtonian mechanics, without changing the predictions of Newtonian mechanics in most situations, we hope for a theory that will unify QED and relativity. It’s a safe bet that such a theory will make the same predictions as QED and relativity in most circumstances.
Misleading, if not incorrect. Light travels at one speed, independent of the speed of the observers. Your statement suggests that the speed of light is sometimes greater than C - i.e. my velocity plus C. It is true that all observers will measure the speed of light to be the same and this seems to be a paradox when you consider that all observers will not agree on the speed of, say a comet racing through the cosmos. However, if you stop thinking of light as a bunch of photon projectiles and think of it as a propagating wave, the paradoxes start to vanish.
I should add that, while Special Relativity is nearly univerally accepted among physicists, there are some questions about General Relativity. So far, every experiment tried to test these possibility upheld General Relativity, but I think we should honor Robert Dicke, who proposed many of these. The poor guy has failed every time, but deserves a lot of credit for trying.
As for Special Relativity, it’s easily demonstrated by at least one practical device: the Global Positioning System. This determines position in part by using extremely precise clocks in orbiting satellites, and it was realized that you had to factor in relativistic effects. If relativity were wrong, the GPS wouldn’t work.
“East is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does.” – Marx
The links put up by <font color=#FF30c0>emarkp</font> actually make the point that relativity is wrong because GPS works!
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Thanks for the short explanation of the Uncertainty principle.
While I do not want to tar everyone with the same brush, it appears that the website that this paper is on is Lambert Dolphin’s. He is famous for pushing the idea that the speed of light is decreasing since creation. I do not know why this goes hand in hand, but it seems that young earth creationists want to discredit relativity for some reason. I guess they feel that Newton was more christian or something.
How could I forget 60C? I was clueless about C at the time. Thanks for helping me pass the class.
Now, as for:
As RM Mentock pointed out, the article suggests that this is in fact a big problem. The GPS satellites were set with the assumption that the satellites would be moving at a constant speed at a specific altitude. However, they’re moving in an accelerating path around the Earth, and the speed wrt the observer (i.e. you and your GPS equipment) is constantly changing. AFAIK, SR says absolutely nothing about an accelerating frame.
So how can you just pretend that the satellites are moving at a constant speed wrt you?
Speed of light depends on medium. Has been slowed to 35 mph in a bose-einstien condensate. Photons have been transmitted at faster than C. Einstein was wrong. B+ for effort.
A. It’s usual to write “speed of light” when we mean “speed of light in a vacuum” and the context makes it obvious what we mean.
B. As far as we can tell, the speed of light is a constant in any medium. All that light does is travel in vacuum and interact with other “particles”. Light appears* to move slower in non-vacuum media because the photons interact with the medium, and are absorbed and new photons are emitted. (And this happens in vacuo, too, but doesn’t affect the apparent speed of propagation).