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A new Einstein cross is discovered

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Re: A new Einstein cross is discovered

#101

Post by bhaak »

oska wrote: post #98
bhaak wrote: post #8

Earlier quoted context omitted.

That's wrong, Quasar is also the German word for Quasar. But it looks like that the Scandinavian and the Slavic languages use the form "kvasar".

Wiktionary is good for finding what languages a particular sequence of characters appears in. https://en.wiktionary.org/wiki/kvasar According to that entry, it appears in both Swedish and Czech (as an alternate spelling). Given the commenter's username is krokku and the fact that "krok ku" means "(a) step forward/towards" in Czech, I think we can assume that the commenter is Czech.

Two entries are not that much. On Wikipedia you can look at the list of articles in other languages.

Or go directly to Wikidata https://www.wikidata.org/wiki/Q83373

Re: A new Einstein cross is discovered

#102

Post by oska »

bhaak wrote: post #101
oska wrote: post #98

Earlier quoted context omitted.

Wiktionary is good for finding what languages a particular sequence of characters appears in. https://en.wiktionary.org/wiki/kvasar According to that entry, it appears in both Swedish and Czech (as an alternate spelling). Given the commenter's username is krokku and the fact that "krok ku" means "(a) step forward/towards" in Czech, I think we can assume that the commenter is Czech.

Two entries are not that much. On Wikipedia you can look at the list of articles in other languages. Or go directly to Wikidata https://www.wikidata.org/wiki/Q83373

Ah, interesting. So I see it also appears in Danish, Estonian and Norwegian.

But with the additional clue from the username I'm still betting on Czech.

Re: A new Einstein cross is discovered

#103

Post by mirimir »

monkeydreams wrote: post #94
mirimir wrote: post #64

Earlier quoted context omitted.

Belated edit: More like ~10^81 times the speed of light. > According to the theory of inflation, the Universe grew by a factor of 10 to the sixtieth power in less than 10 to the negative thirty seconds, so the "edges" of the Universe were expanding away from each other faster than the speed of light [0] It seems that the universe was on the order of ~1 meter in diameter then.[1] So the "'edges' of the Universe were e…

> Belated edit: More like ~10^81 times the speed of light. I have no grounding in physics on which to place this hunch but... doesn't this sound like a wee fudge factor to make the Big Bang theory fit evidence? I am reminded of the concept of "aether" and "land bridge theory" where people had a workable hypothesis except for the niggly little problem that the hypothesis was contraindicated by some of the evidence.

I wonder about that too.

Re: A new Einstein cross is discovered

#104

Post by waynecochran »

btilly wrote: post #89
waynecochran wrote: post #81

Earlier quoted context omitted.

I don’t understand the geometry and why they occur at these four positions 90 degrees from each other?

There is a long explanation at https://physics.stackexchange.com/questions/14056/how-does-g... that gives all of the details. Here is a simplified version. First you need to understand Fermat's principle. Light will follow a particular path from A to B when all nearby paths take approximately the same time as that one. Distant paths may be faster or shorter - consider a straight line vs a mirror. But if nearby paths…

Wow. Thanks for the detailed answer.

Re: A new Einstein cross is discovered

#105

Post by Grue3 »

>One of the most striking conclusions of Albert Einstein's theory of general relativity is that the trajectory of light curves in the presence of matter.

A good example of "garden path sentence" [1]. "The trajectory of light curves in the presence of matter is what?". It took me a while to realize that curves is supposed to be a verb and not a noun.

[1] https://en.wikipedia.org/wiki/Garden-path_sentence

Re: A new Einstein cross is discovered

#106

Post by mcguire »

rough-sea wrote: post #55
saagarjha wrote: post #53

Earlier quoted context omitted.

Isn’t the natural extension of things being “closer together” that they were at a singularity at some point (the Big Bang)?

Nope. The universe is infinite, according to the model. We see observe galaxies speeding away from us in every direction - and it seems unlikely that the earth was the exact center of the Big Bang.

But...if it is infinite in extent and (nearly) uniformly dense, how would the density decrease to the current value?
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