General Relativity

In the previous posts, whether it was a spaceship or any other system, we only considered uniform-velocity motion where the speed v stays constant the whole time!!!!!!!

That was exaaaactly!!!! the only case we looked at right??!?!?!?!!!! We limited ourselves to that special case

Just~~~~ that case only yup yup lol yup lol that’s what we call special relativity

It’s called special relativity because it only looks at the special situation where the other system’s velocity is constant,

and this special relativity was published by Einstein in 1905

And now for some stuff I’ve picked up along the way,

he published special relativity in 1905, and he wanted to publish general relativity which covers the general situation where velocity isn’t constant…

well….Einstein did end up publishing this one too!!!

But,,, it apparently took 11 years to publish that general relativity……hehehe

What on earth did Einstein do during those 11 years….. ???

He thought the key to general relativity was in Riemannian geometry, so for 11 years he apparently just studied that difficult math..he.he lollollollollollol

Wow~~~ how cornered must he have felt back then!?!?!?!!! The thought that if he mastered Riemannian math

he could figure out general relativity based on special relativity…. lollollollollollollollol

But anyway, in 1916 Einstein ended up publishing general relativity, which encompasses situations where the acceleration isn’t 0 hehe

​

I’m not some madman who’s going to cover in this post the general relativity that took Einstein 11 years…..;;

Just….

please treat the content of this post as just a ‘fun story’..hehelollol​

At my level, the Key to general relativity is

that the person inside these two situations

has no way at all to identify or feel which situation they’re in

(Where the heck am I right now!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!)

(Am I on Earth!!!!!!!!!!!!!!!!! Or am I inside an elevator accelerating at the same rate as gravitational acceleration!!!!!!!!!!!!!!!!!!!!!!)

(I have no idea!!!!!!!!!!!!!!!!!!!!!!!!!!! That kind of situation….)

But, if the person on the right fires a laser (light) over there????

The light will bend downward right? Right????????????(not pee)

But aren’t the two the same? lollollollollollollollollollollol You said they can’t be distinguished!!!

Which means, that on Earth too light bends!!!!

In other words, “light bends due to gravity!”

At the time, this was apparently groundbreaking.

Because, they only thought light would go in a straiiiiiiight line

Light bending? Yeah right;;;; that’s apparently how they thought

But anyway, the story goes that even when you shoot light on Earth, it bends because of Earth’s gravity….

It ends up like the picture above right?!?!?!

So!!!! Einstein tries to observe this!

The moon, Mars, and Mercury next to Earth are pretty close, but their gravity isn’t strong enough to observe the light bending…

He had Jupiter, the biggest planet in the solar system???, in mind,

but Einstein knew even that wouldn’t be enough…..he

So he picks the Sun!!!!! He knew that light passing by the Sun could bend,

but Einstein failed at this observation…T_T T_T T_T T_T because of the outbreak of the world war… you know, this and that going on….

There were apparently lots of people trying to do these experiments, but the most famous one is Eddington!!!!!(the British astronomer!!!!!)

And he succeeded in the observation, and in 1919, 3 years after general relativity was published, he announced the research results

and that announcement was published in the Times as ‘Revolution in science - New theory of the universe - Newtonian ideas overthrown.’

Apparently that’s how it was printed lollollollollollollollol

Anyway, this absurd relativity theory was also experimentally verified and got officially recognized….

or so they say…

So what did this guy observe in simple terms,

Starlight that originally shines and is visible like this

when it passes close by the Sun

bends like this, and to our eyes what was originally one star will look like 2…

and when they actually tried it~~~~ that’s how it was~~~~~~~~~~~~~~~~~~

So

in the end we could even write equations like this.

‘Gravity’ ~ ‘Curvature of spacetime’

That is, under general relativity, the existence of “gravitational waves” becomes obvious….

To put it simply to help understanding, if I make up a way to say it,

the fact that suddenly!!!!!!after a supernova some star disappeared means, one way or another, that space was curved and then as the curved space straightens out, or as the stretched-out space gets twisted, that wave would propagate…..that sort of….hehehehe

(Is that right? I’m not someone who majors in this so I don’t really know. This is roughly the extent of what I understand…)

Sometimes when you watch the news you hear about gravitational waves~ gravitational waves~

why do they want to find this gravitational wave so badly

well, if general relativity is correct, then gravitational waves must also exist, but they haven’t been able to clearly show that yet

(One thing I heard is that gravitational waves are so small that observing them is that much harder… that’s what I heard. I haven’t heard much talk about this field,,, so if anyone knows it well…. I’d appreciate it if you could teach me.hehehehehehe)

I wrote this around 2014, and then in 2017 they detected gravitational waves….shiver shiver shiver;; the years;;

Originally written in Korean on my Naver blog (2015-08). Translated to English for gdpark.blog.