Of Einstein's genius

This man oozes brainpower. Maybe not in this picture, though.

The real genius in Einstein's work is in the fact that he discovered a fundamental property of the universe from only a few assumptions.
He set the speed of light as constant in different frames of reference and developed the mathematics of Lorentz transforms further to come up with one of the most beautiful theories in physics.

While usually in physics direct evidence and data is studied to deduce a phenomenon, he inductively derived his theory having no evidence at all. He made his own axioms and derived everything again from them. And the best part is that it worked, at least in theory. Despite a few physicist immediately recognized his genius, his theories were not completely recognized by the scientific community at the beginning, especially when the paper for his theory of Special Relativity presented no references. Einstein's reasoning was outside the lines, but sharp, nonetheless, and it proved no mistakes.

Evidences for his special theory of relativity started to come up only much later, around 1932, with the Kennedy-Thorndike experiment testing the dependence of the speed of light on the velocity of the measuring device.
Direct evidences of the general theory of relativity are still feeble, even though it is now a firmly accepted theory.

No, it is not photoshopped

The difficulty in testing this theory (linked to the difficulty to discover it) lies in the fact that we need astronomically strong gravitational fields in order to detect the space-time fabric and its tiny ripples: the gravitational waves. I did not use the word astronomical by chance, as the best empirical evidences come from deep space. Usually quasars (active galactic nuclei), which are very far, but bright x-ray sources, are used as indirect test for the theory of general relativity, as their ginormous gravitational field can bend light. Pictures of galaxies behind quasars could be worked out from their light being bent right into our eyes (or telescopes), forming "rings" of light around the quasars.

A more direct evidence of general relativity would be detecting its evident result: gravitational waves. Unfortunately, these waves are far less energetic than anything we can imagine, making it easy to let them disappear into the much higher and chaotic background of radiation. Experiments exist trying to achieve the impossible through interferometers, but a much more concrete evidence, at least for now, is presented by binary pulsars.

Not the most scientifically
accurate gif I could find,
but surely the coolest.

Binary pulsars move into space and their gravitational field emits gravitational waves, which is a leak of energy from the system. Everything, in fact, emits gravitational waves, but for small (less heavy, to be precise) objects their emission is undetectable. As energy is leaking from the binary system of pulsars, their period of revolution will get slightly slower than usual and with enough time passed, this accumulated time will get significantly big to be measured. This is not a direct evidence, as the energetic leak that slows the period down is not necessary given by gravitational waves, but that is the only phenomenon we know that could cause it, for now, and Einstein's model works really well when applied to these bodies, so it is still evidence, even if indirect.

When I started writing this post, it was meant to be an introduction to one big recent news in science in one of the FSND series. I was so excited writing about how marvelous Einstein's theories are that it got too long and I decided that it would easily be a blog post on its own.

The news regards the recent first visible-light evidence of gravitational waves from a pair of dwarf stars, and I'll now leave you in a pointless cliff-hanger (pointless as the news is already out elsewhere) as I will talk about it in the next Fortnightly Science News Digest on 15 September.