Einstein's importance

chaszz

I get the impression that special relativity was "in the air", that others such as Poincare were working toward it around 1900 - 05. Is it likely that it would have been discovered without Einstein? Is it correct to say that on the other hand general relativity would not have been proposed and formulated without him, and that this was therefore his more important contribution?

bcrowell

I find it hard to believe that SR would have gone undiscovered for much longer. I find it easy to believe that GR would have gone undiscovered until ca. 1950 or even later.

ghwellsjr

First off, I wouldn't say it was discovered. I would say it was created out of the mind of a genius. And I don't think any of the scientists prior to Einstein would have ever thought in the terms that would have allowed them to come up with it because it was such a radical departure from the way everyone else was thinking at the time. I'm talking about the notion that time and space were not absolute but relative. That was really Einstein's only novel contribution to what Poincare, Lorentz and others had already formulated and the reason he deserves all the credit for formulating the Theory of Special Relativity. Poincare had plenty of time to abandon the notion of an absolute ether rest frame but he couldn't and I doubt he ever would. Lorentz Ether Theory was a perfectly viable theory that could have sustained science for a very long time.

I believe if Einstein hadn't come along when he did, it would have taken someone else that was not already entrenched in the science establishment of the time and could think "outside the box". That could have taken a generation of several decades for all those old scientists to die off and a new set that were not so steeped in the old way of thinking. So I think Einstein fully deserves all the credit we can give him for SR.

Pengwuino

Wasn't SR written down before Einstein, it just wasn't given a correct physical interpretation? By lorentz maybe?

ghwellsjr

No, the principle of relativity was and the principle of the speed of light propagation was, but they were not perceived to be compatible with each other. They thought only one could be considered true. The scientists at the time chose the principle of relativity but in the context of an absolute ether rest state which was the only place that they believed that light could propate at a constant speed. Einstein showed that by giving up the concept of absolute space and time, you could consider both principles to be true for all inertial observers, not just those at rest with respect to the supposed ether.

harrylin

SR had effectively been worked out (although not yet fully developed) just before Einstein handed in his manuscript; it was originally called the theory of Einstein and Lorentz.

This was also indicated in Einstein's summary of the new theory in 1907 which he based on Lorentz-1904 and Einstein-1905, as well as by the bundle "the principle of relativity" which starts with papers by Lorentz (funny detail: it used to be "Lorentz et al", but nowadays it is presented as "EINSTEIN et al" ). For a discussion of the topic, see:
http://www.physicsforums.com/showthread.php?t=207148

Einstein was certainly the main force behind GR, although others also contributed. For a discussion, see:
http://en.wikipedia.org/wiki/History...ral_relativity

Best,
Harald

HallsofIvy

Lorentz's formulas were derived pretty much ad-hoc to explain the Michaelson-Morley experiment. But he did then come up with a clever theory in which the changing electro-magnetic field due to the motion caused something like a measuring stick to contract exactly enough to give the null result. Othere experiment's however, showed that that would not work. Einstein's importance was that he extended that theory to include the contraction of space itself.

harrylin

When and where did he do so? Like Lorentz, he derived contractions of objects (despite your claim that "that would not work"). See: http://www.fourmilab.ch/etexts/einstein/specrel/www/ (in particular section 4).