“This image of galaxy cluster Abell 2744, also called Pandora’s Cluster, was taken by the Spitzer Space Telescope. The gravity of this galaxy cluster is strong enough that it acts as a lens to magnify images of more distant background galaxies. This technique is called gravitational lensing.” [nasa.gov]
“Gravitational lensing works in an analogous way and is an effect of Einstein’s theory of general relativity – simply put, mass bends light. The gravitational field of a massive object will extend far into space, and cause light rays passing close to that object (and thus through its gravitational field) to be bent and refocused somewhere else. The more massive the object, the stronger its gravitational field and hence the greater the bending of light rays – just like using denser materials to make optical lenses results in a greater amount of refraction.” [cfhtlens.org] > further reading
Yes, how many times must a man look up
Before he can see the sky?…
…The answer my friend is blowin’ in the wind
The answer is blowin’ in the wind.
November 1915, one hundred years ago, Albert Einstein presented his field equations for General Relativity.
And since then the world has been trying to figure out what it is.
Well okay, not the whole world, but me for sure. Three years ago in a happy summer, I ran across my sister-in-law studying astronomy and the theory of relativity out of pure interest. That led to looking up at the night sky. I then learned about the speed of light. And space-time. And red shift. And entropy, entanglement, the cat-in-the-box, particles, accelerators—so much. It was completely awesome.
But when it comes to explaining the general theory of relativity to myself (unthinkable explaining it to anyone else), I can’t help but recall one of Einstein’s own alleged statements:
If you can’t explain it to a six year old, you don’t understand it yourself.
I haven’t sat down and studied relativity in depth, but I’ve been fortunate enough to have been shown a range of other resources, many of which completely changed my original, sour feelings for physics.
On this 100-year anniversary mark, I cannot explain the theory of relativity in this post, but I’m quite ecstatic to share some of the places I’ve had a lot of fun trying to learn about it:
Four-part series but incredibly exciting:
Simple and ridiculously cute:
And finally, as close to the six year old level as I’ve been able to find:
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