Over a century ago, Einstein wrote his theories of special relativity and general relativity. Within those theories, he predicted that, as an object moves faster, it slightly contracts in length. However, 50 years later Penrose and Terrell predicted that what one would see is instead that the object is rotated. In a recent experiment, physicists proved that this Penrose-Terrell effect is actually real. Let’s take a look.She is a big Einstein idolizer. Her favorite prop is an Einstein bobblehead.
Let me review the basic facts.
The relativity length contraction was discovered by Fitzgerald in 1889 and Lorentz in 1892. Lorentz also discovered time dilation in 1895. Both of them used these to explain the 1887 Michelson-Morley experiment.
Poincare in 1905 and Minkowski in 1907 explained these as a new geometry of spacetime. In their interpretation, the spacetime distortions are not real, but an artifact of choosing a frame in the 4D non-euclidean geometry. This interpretation was quickly accepted, and is the dominant one today.
Dr. Bee starts:
0:00 Albert Einstein totally changed our understanding of space and time. ...No, Lorentz and others made those remarkable predictions 10+ years ahead of Einstein. They said that the motion actually actually made the Michelson apparatus shorter. I think most physicists today would say that it only appears shorter.Einstein’s theory of 0:46 special relativity makes two most remarkable predictions. The first is time dilation, 0:52 the other one is length contraction. Time dilation means that if an object moves faster 0:58 than its internal time passes slower. Length contraction means that the same fast-moving 1:05 object will also be shorter. It’s not that it appears shorter, it actually is shorter.
In 1931, a group of scientists went so far 1:24 as to publish a book called “100 authors against Einstein.” It’s an interesting historical summary 1:31 of why people rejected Einstein’s insights, more than 2 decades after he had put them forward.Her opinion is very strange. Lorentz and Poincare had all the equations and predictions before Einstein. The only way to credit Einstein for relativity is to say that he had a superior philosophical construction. If the Lorentz contraction is real and the 1931 book was wrong to say that Einstein had a philosophical construction, then Lorentz had it all before Einstein.1:38 Some of them claimed Einstein’s maths is wrong. Some said the maths is right, 1:44 but they did it earlier.
The most frequent objection though was that they thought 1:49 Einstein’s theory is merely a philosophical construction. They thought that special 1:55 relativity tells us something about the way we see things. Not about how they really are. 2:01 Well, they were wrong. We know that length contraction is real. A moving object really is 2:08 shorter.
Here is what Poincare wrote in 1905, before Einstein:
But the question can still be seen form another point of view, which could be better understood by analogy. Let us suppose an astronomer before Copernicus who reflects on the system of Ptolemy; ...He says his view is like Copernicus rejecting Ptolemy, putting a new view on the same data. The relativity contraction is only apparent, due to our methods of measurement.Or this part which would be, so to speak, common to all the physical phenomena, would be only apparent, something which would be due to our methods of measurement. ...
so that the theory of Lorentz is as completely rejected as it was the system of Ptolemy by the intervention of Copernicus.
This is the modern view of relativity. It was popularized by Minkowski in 1907-8, and accepted ever since. Einstein is only credited because of a mistaken belief that he contributed to this modern view. In fact, the view was published before Einstein, and Einstein rejected it when he learned about it.
Most of Dr. Bee's video is about a new paper confirming a visual illusion that Penrose discovered.
