Probing General Relativity's Limits

think it would be great to come up with ideas that people were still trying to improve upon in a century.

That is the situation with Einstein's structure of ideas, especially the general theory of relativity.

Physicists are probing its limits not in the hope that they can somehow over come it and erase it from the blackboard of history -- that won't happen --but in the expectation that in time somebody will do to Einstein what he did to Newton. Roughly speaking, Einstein showed that Newton was right about a special case within a broader situation. Outside of this special case (a stable framework for observations, within which objects move at slow velocities) things work in non-Newtonian ways.

Could even Einstein's understanding of physics turn out to be a special case within a broader situation. It is almost certain that this WILL happen. The question is: where do the Einsteinian rules break down? Find that out, and come up with the broader theory, and your name my friend will be as immortal as both Ike's and Bert's.

Some of the work of Hawking and Penrose gives us an idea of how this might happen to some lucky still unspecified physicist. Their deductions from Einsteinian principles tell us that the black hole horizon is not a physical thing. It is a point beyond which nothing returns. But it is like a "city limits" in space. Not a physical thing like a castle's walls.

But maybe Einstein (in terms of the inferences rigorously drawn from his premises) is wrong. Maybe there is something physical.

If he is wrong, then maybe this border that black holes have will turn out to create echoes. Waves -- specifically gravitational waves -- might bounce right off of it. This is a hypothesis that a number of people are testing, among them Niayesh Afshordi of the Perimeter Institute.

The scientists postulating a sort of wall around a black hole did report a signal that sounded like an echo of a gravitational wave generating event in August 2017. Other scientists say that the Permeter Institute has misunderstood its data, and there was no true echo. The dispute will likely continue for some time yet.

I'm not going anywhere special with this but this idea of grey-bearded geniuses debating the echoes of gravitational waves and, implicitly, the limits to general relativity, is fascinating to me.

Like, wow, man....

Comments

A Story About Coleridge

This is a quote from a memoir by Dorothy Wordsworth, reflecting on a trip she took with two famous poets, her brother, William Wordsworth, and their similarly gifted companion, Samuel Taylor Coleridge. We sat upon a bench, placed for the sake of one of these views, whence we looked down upon the waterfall, and over the open country ... A lady and gentleman, more expeditious tourists than ourselves, came to the spot; they left us at the seat, and we found them again at another station above the Falls. Coleridge, who is always good-natured enough to enter into conversation with anybody whom he meets in his way, began to talk with the gentleman, who observed that it was a majestic waterfall. Coleridge was delighted with the accuracy of the epithet, particularly as he had been settling in his own mind the precise meaning of the words grand, majestic, sublime, etc., and had discussed the subject with William at some length the day before. “Yes, sir,” says Coleridge, “it is a maj...

The Lyrics of "Live Like You Were Dying"

Back in 2004 Tim McGraw recorded the song "Live Like You were Dying." As a way of marking the one-decade anniversary of this song, I'd like to admit that a couple of the lines have confused me for years. I could use your help understanding them. In the first couple of verses, the song seems easy to follow. Two men are talking, and one tells the other about his diagnosis. The doctors have (recently? or a long time ago and mistakenly? that isn't clear) given him the news that he would die soon. "I spent most of the next days/Looking at the X-rays." Then we get a couple of lines about a man crossing items off of his bucket list. "I went sky diving, I went rocky mountain climbing, I went two point seven seconds on a bull named Fu Man Chu." Then the speaker -- presumably still the old man -- shifts to the more characterological consequences of the news. As he was doing those things, he found he was loving deeper and speaking sweeter, and givin...

Five Lessons from the Allegory of the Cave

Please correct me if there are others. But it seems to be there are five lessons the reader is meant to draw from the story about the cave. First, Plato is working to devalue what we would call empiricism. He is saying that keeping track of the shadows on the cave wall, trying to make sense of what you see there, will NOT get you to wisdom. Second, Plato is contending that reality comes in levels. The shadows on the wall are illusions. The solid objects being passed around behind my back are more real than their shadows are. BUT … the world outside the the cave is more real than that — and the sun by which that world is illuminated is the top of the hierarchy. So there isn’t a binary choice of real/unreal. There are levels. Third, he equates realness with knowability. I only have opinions about the shadows. Could I turn around, I could have at least the glimmerings of knowledge. Could I get outside the cave, I would really Know. Fourth, the parable a...

Jamesian Philosophy Refreshed

Search This Blog