How galaxies can travel faster than the speed of light

[disappoint]

http://www.youtube.com/watch?v=myjaVI7_6Is

Pretty neat.

 

[Thebobo]

Neat.

30 some years ago when I was a stoner I envisioned going .999999999999 the speed of light and then I would have a telescoping bowl that would shoot out and hit the speed of light and I would be smoking pure enegery! Good bye NSA job!

 

[Miramonti]

Very cool. I'll briefly pretend I understood all that while I post my reply.

 

[JTsyo]

Neat.

30 some years ago when I was a stoner I envisioned going .999999999999 the speed of light and then I would have a telescoping bowl that would shoot out and hit the speed of light and I would be smoking pure enegery! Good bye NSA job!

Obviously it was the pot talking and not physics.

 

[KDOG]

That was cool. Mind. Blown.

 

[KB]

Does this mean Einstein was wrong? Or just that we are going one way and the galaxy is going the other way so the total distance between us is growing faster than the speed of light?

 

[child of wonder]

Does this mean Einstein was wrong? Or just that we are going one way and the galaxy is going the other way so the total distance between us is growing faster than the speed of light?

The expansion of spacetime is not bound by Special Relativity.

In other words, it's not the galaxies that are moving at the speed of light relative to us, it's the space between us and the galaxies that is expanding at an increasing acceleration.

 

[Paul98]

Does this mean Einstein was wrong? Or just that we are going one way and the galaxy is going the other way so the total distance between us is growing faster than the speed of light?

No, it's that space is expanding faster than the speed of light. Like you could have two stationary objects the space between them could be expanding but the object wouldn't be moving in space.

And for your second part it doesn't make sense with how relativity works. Speed is relative aka there is no absolute speed anything is moving. Speed is only relative, if I am on earth and see two spaceships moving through space both moving in opposite directions. Lets say I see one moving at -.8c, and the other moving .8c in my frame of reference. I then want to know how fast they are moving away from each other in a spaceships frame of reference I wouldn't just add +.8c+.8c, I instead would use this formula http://en.wikipedia.org/wiki/Velocity-addition_formula and I would get that in the frame of a spaceship the other spaceship is moving at .976c

In your own frame of reference your velocity is 0, in a car driving driving by your house it's 30mph, or any other speed just depending on the frame of reference.

 

[Fritzo]

Very cool. I'll briefly pretend I understood all that while I post my reply.

It's not that hard to visualize. Imagine the universe like a balloon that's inflating. On the surface of the balloon, a drop of water is running down the side and away from a spec of dust.

As the balloon inflates, the balloon's surface stretches, and this adds distance between the water drop and spec of dust. On top of that, the water drop is moving, so you can add the velocity of the movement and the effective velocity caused by the balloon inflating.

Most of astrophysics can be explained with a balloon

 

[Malak]

Nothings actually moving. It's all a lie.

 

[HeXen]

Nothings actually moving. It's all a lie.

Or could be completely wrong. Should all be taken with a grain of salt.

 

[Agent11]

Did a double take on the last bit, is that accurate?

 

[Paul98]

Did a double take on the last bit, is that accurate?

which part?

 

[Agent11]

The part about photons not being able to outrun a galaxy and it not being visible... Doesn't sound right.

In my understanding in relation to it's photons the galaxy is moving at normal speeds, and they will keep doing their thing unless occluded from the observers perspective.

 

[disappoint]

The part about photons not being able to outrun a galaxy and it not being visible... Doesn't sound right.

After the galaxy leaves our observable universe, into the part of the universe that is not observable, the galaxy is moving away from us faster than c. After that point, any photons emitted by the galaxy will not be observed by us because the photons cannot outrun the galaxy's velocity away from us.

In my understanding in relation to it's photons the galaxy is moving at normal speeds, and they will keep doing their thing unless occluded from the observers perspective.

I'm not sure if you are picturing the galaxy moving through space. Space itself is expanding very fast at the edge of the observable universe. Space itself is expanding at near c. This space, is spacetime the photon must travel through.

 

[Dari]

All this sounds like theoretical physics bullshit. It may appear to travel faster than light but it really isn't...

 

[Matthiasa]

Figured it would deal with with the expansion of the universe.
It is a shame how little most understand this stuff and that they simply parrot off something someone making overly generalized statements said.


As already noted the galaxies are not moving faster than the speed of light, it is the distance of space-time that can be.
A standard example to explain that typically is a balloon’s expansion. Every single point on the balloon is expanding way from each other.

 

[chiza]

I've always wondered what space is expanding into....

 

[phucheneh]

I've always wondered what space is expanding into....

I've had trouble with that, too.

I believe the answer is essentially that it isn't expanding into anything. There is no 'new' space being formed out at the 'edge' of the universe. It's just that the distance between everything is growing. Think of if as a slowly inflating balloon. With a bunch of planets and space bullshit floating around inside of it. But unlike a balloon, the the stuff inside it is getting less dense instead of more dense as the balloon grows.

The 'edge of space' thing is still troubling, though. As in, the universe is 13 billion years old, and we have observed objects roughly that age (albeit we're seeing how they looked close to 13 billion years ago)...why would there not be anything past that? Wouldn't it just be a 'false horizon' of sorts?

 

[Murloc]

as a kid I thought universe was expanding into an infinite brickwall.

 

[BrokenVisage]

It may be interesting to note that at even while sitting still we're all technically moving through space at about 2.7 million MPH.

http://blogs.howstuffworks.com/2010...re-you-moving-through-the-universe-right-now/

 

[Triumph]

I've had trouble with that, too.

I believe the answer is essentially that it isn't expanding into anything. There is no 'new' space being formed out at the 'edge' of the universe. It's just that the distance between everything is growing. Think of if as a slowly inflating balloon. With a bunch of planets and space bullshit floating around inside of it. But unlike a balloon, the the stuff inside it is getting less dense instead of more dense as the balloon grows.

The 'edge of space' thing is still troubling, though. As in, the universe is 13 billion years old, and we have observed objects roughly that age (albeit we're seeing how they looked close to 13 billion years ago)...why would there not be anything past that? Wouldn't it just be a 'false horizon' of sorts?

Yeah, I'm sure somebody smarter than me *thinks* they understand this. It's almost as if space is created at the edge of the universe as soon as an object - anything - goes into it. Considering that, it seems quite trivial to say that there is an edge to the universe when there's nothing stopping you from expanding that edge. In that respect, the term end could be more aptly used than the term edge: the edge being dictated by the radius of the outermost galaxies in a 3 dimensional sphere. But there is no "end" of space.

For purposes of explaining the OP's video, it might be more helpful to draw the expansion of the universe on a 2 dimensional line with a galaxy on either end.

 

[Paul98]

All this sounds like theoretical physics bullshit. It may appear to travel faster than light but it really isn't...

They actually are, just not through space. They are traveling through space at slower than C, but space time is also expanding so the total distance in spacetime between us and them is increasing faster than C.

 

[Paul98]

It may be interesting to note that at even while sitting still we're all technically moving through space at about 2.7 million MPH.

http://blogs.howstuffworks.com/2010...re-you-moving-through-the-universe-right-now/

This is incorrect, we aren't "technically" moving through space at any one speed. Speed is relative so respect to one frame of reference we are moving at 2.7mil MPH, but with respect to another one we are moving .99999c, and with respect to our self we aren't moving at all,... just choose a frame of reference and we can see how fast we are moving with respect to it. One frame of reference isn't better than the other and there is no absolute frame of reference.

 

[Paul98]

I've had trouble with that, too.

I believe the answer is essentially that it isn't expanding into anything. There is no 'new' space being formed out at the 'edge' of the universe. It's just that the distance between everything is growing. Think of if as a slowly inflating balloon. With a bunch of planets and space bullshit floating around inside of it. But unlike a balloon, the the stuff inside it is getting less dense instead of more dense as the balloon grows.

The 'edge of space' thing is still troubling, though. As in, the universe is 13 billion years old, and we have observed objects roughly that age (albeit we're seeing how they looked close to 13 billion years ago)...why would there not be anything past that? Wouldn't it just be a 'false horizon' of sorts?

http://www.dailymotion.com/video/xv...-edge-to-the-universe_shortfilms#.Ubx40Pk3srs