/sci/ - Science & Math

gravity bends photons

You know how a normal lens causes light to bend so it's focused on a point. It's like that, only with gravity.

Gravity bends light, or focuses it. For example imagine a quasar lets out 2 pulses of light at a 60 degree around, and the two light beams pass a galaxy. The galaxy will bend the light beams towards eachother.

>>2668190
meant to say at around a 60 degree angle.

Ah, okay, now it makes more sense to me. I'm obviously not a very bright individual.

>>2668181
i love bent photons. much more fun that way.

hmm i think it's more like the gravity is bending space, and the photons are traveling "straight" but it's actually bent
the light gets distorted like a lens

>>2668259
>gravity is bending space

This is why I got confused .. A part of me refuses to believe that you can "bend space".

this

>>2668274
Then you might want to read this book.

>>2668279
But how are those beams of light being bent? Until this kind anon explained it to me in the way he did, it didn't make sense to me.

>>2668274
well it makes more sense than bending light, something that has no mass
space probably doesn't have mass either but it's affected by gravity

light takes the shortest path

around massive objects, the shortest path is not a straight line.

>>2668293
I know I know ..
But I worry, that's all. You know how damn near everyone accepts the Big Bang theory to explain the creation of the universe? I can't. I accept it as an answer to explain the creation of say a galaxy or something, but I will never believe that something as infinite as the universe has a beginning or end ..
I worry that I'll be taught something that doesn't feel right, if that makes sense.
Regardless, I'll read it. I have to now.

m dum lol

>>2668300
You can either think of it as light traveling in a straight line through curved space, or, less accurately, as the path of photons being bent as they pass through a gravitational field, like if you threw an asteroid near a planet.

>>2668306
Just no.

>>2668293

But not that version.
I bought that version and it's a piece of shit.
It's bizarrely sized, printed sloppily and the binding sucks.

Spacetime around a massive object (such as a galaxy cluster or a black hole) is curved, and as a result light rays from a background source (such as a galaxy) propagating through spacetime are bent.

http://en.wikipedia.org/wiki/Gravitational_lens

>>2668307
>but I will never believe that something as infinite as the universe has a beginning or end

Why not? Are you one of those people who believes in an afterlife simply because you can't wrap your mind around the concept of not existing?

>>2668307
The universe isn't infinite. It's just orders of magnitude bigger than we are.

You can try reading Einstein's Telescope by Evalyn Gates.
The actual book is about Dark Matter and Dark Energy but the first few chapters give a nice intuitive understanding of gravitational lensing and relativity.

>>2668319
Just doesn't seem right to me. We see things on Earth have beginnings and ends, and a handful of things in space have a beginning and an end so it's only natural that we assume that everything has a beginning and end. And I believe that planets, stars, etc. have beginnings and ends but I can't when it comes to the universe itself. The vastness, excluding the stars and planets within it, I can't believe that it has a beginning or an end. It was always here and will always be here.
And no, once you die, you die. No more living, end of story. The idea of an afterlife is just something people tell others (and themselves) to sort of comfort them about death.

>>2668326
>The universe isn't infinite.

Why would you say that? You believe that it has an end somewhere? Just SPLAT, a giant wall that ends the universe?

>>2668338
>but I can't when it comes to the universe itself. The vastness, excluding the stars and planets within it, I can't believe that it has a beginning or an end. It was always here and will always be here.
It wasn't and won't always be. Just get over it.

>>2668341
basically

>>2668311
Just yes, spacetime isn't exactly best modelled by 3 spacial dimensions and one time dimension. In a vacuum sure, but the more massive the object the more spacetime around it resembles 2 spacial dimensions and 1 time dimension, like the surface of a sphere. See the holographic principle.

When I was a kid, I used to think that, existance, reality itself, is a circle of circles, all connected to each other, and when all energy in the universe disappears through entropy, it isn't actually being lost due to being transformed into an unusable form, but actually being transferred into the "next" circle, where once it accumulates to a large enough point, causes a big bang, thus filling out a "new" circle, and leaving the old one "empty", and it goes on like this forever because it's a circle of circles.

I was a weird kid..

>>2668341

Not exactly. I think the correct way of thinking is that the universe is finite but unbounded. The universe isn't expanding outward from single point, rather space itself is literally expanding. It can keep going as long as it wants, but it will never be infinite.

>>2668347
And your proof is a collection of a few older stars and galaxies that are slowly drifting away or into one another?
Is that your proof that the universe, sans stars, planets, etc. was created at some point and will end at another?

>>2668375
Like being in a bubble that's forever expanding, only without the threat of the bubble eventually popping?

>>2668384

It ends on judgement day when god brings the faithful unto him and recreates the universe anew.

>>2668375
There are an infinite number of natural numbers but they can be multiplied indefinitely and never reach the reals. Our information horizon is finite, but I don't see any reason to hold space to be finite.

>>2668388

>>2668338
Incorrect. We already know what began the universe. The models based on the assumption it was a random quantum fluctuation correctly and precisely predicted the curvature of space over a decade before the instruments to measure it were invented.

We also have a fairly good idea of the way it will end. Entropy will increase, the usable energy of the universe will decrease, anything but inert matter will cease to exist, and after a long time even the it and its constituent protons will decay into an unmoving cloud of fundamental particles.

>>2668384
Here you go: http://www.youtube.com/watch?v=7ImvlS8PLIo#t=8m18s

>>2668405
Random?

>>2668405
So at one point, nothing new will be created? It'll all just .. stop .. no more .. just like that?
That doesn't seem right to me, not in an infinite universe. I believe galaxies will end but that new ones will be created, just like stars and planets and so on. But the universe? C'mon, certain things will not just suddenly stop being made somehow.
Like I said before, it's only natural to want to believe that everything has a beginning and end, but I will never believe the whole universe was created in some giant explosion or will end in some other fashion.

>>2668423
Yes. The sum total energy of the universe is exactly zero. The big bang is virtual particle production on a massive scale.

>>2668432
No, it's natural to assume you are a part of a larger whole that will exist forever and ever and therefore on some level everything will be ok. But it won't. The universe is dying as we speak. The amount of non-entropic energy that exists right now is less than it was when I started this paragraph. All the galaxies that will ever coalesce from hydrogen gas (read: not made by collisions with other galaxies) have already been formed. Even in our own galaxy, the number of long-lived red dwarf stars is already twice that of all the other types of stars put together.

>>2668433
Do you mean algorithmically random or absolutely random?
http://en.wikipedia.org/wiki/Kolmogorov_complexity

>>2668219

this comment made my day.

>>2668432
>C'mon, certain things will not just suddenly stop being made somehow.

This man believes that resources just pop out of thin air in an infinite supply. That sentence is as idiotic as "my fridge will not suddenly stop being full of food somehow."

>>2668444
Give it time, it wont spell the end for the entire universe, just the area around what we can see with our own eyes.
Stars will go out, galaxies will go out. But at the same time, we see new stars being made, we're getting a better understanding of how galaxies are formed exactly.
I doubt we'll ever agree .. but we can agree to disagree, right?

>>2668446
Nothing quite so specific. I meant random as referring to the fact that quantum phenomena arise from probabilistic vectors as opposed to the "throw ball at X velocity, hits the ground at Y location" of macroscopic interactions.

Wait enough time and quantum fluctuations will produce you sitting in your chair, with all the memories you have now, along with a set of gigantic tits and a winged guardian named Jenkins.

>>2668471
>Give it time, it wont spell the end for the entire universe, just the area around what we can see with our own eyes.
WAIT A GODDAMN MINUTE
> it wont spell the end for the entire universe
WHAT HAVE I DONE
> just the area around what we can see with our own eyes
DAMMIT.

>>2668471
All the energy that will ever exist has already been created, and it will be expended in a finite amount of time. Period. Your belief that it will go on forever is childish wish-thinking.

>>2668476
I want a winged guardian named Jenkins...

Who wants some Lawrence Krauss? For the creation/expansion discussion going on.

http://www.youtube.com/watch?v=7ImvlS8PLIo

>>2668483
If you say so. There are still so many things we have yet to discover and fully understand, you know. Give it time.
Remember when we used to believe in a second moon? Or when we thought there was a demon planet that would come hurdling into us? Or that there was a planet between the sun and Mercury? Over time, we've learned things and now know better.

>>2668493
Already been posted. Read the thread.

>>2668483

It's childish wish-thinking or some 'New Age' pseudo-religious woo. Funny how they're essentially interchangeable.

>>2668181
Incorrect. Gravity bends spacetime. Photons are always travelling in straight lines from its own point of view.