How galaxies can travel faster than the speed of light

[Paul98]

It's no more real than a bird either.

It's one that everyone in the universe can agree on from wherever they are by performing the same experiment. I don't know how someone in andromeda is going to measure the frame of reference of you sitting at your desk.

What you are doing is going to confuse people into thinking that there is an absolute frame of reference. You perform your experiment and I perform mine we can transform the results into what ever frame we want.

 

[phucheneh]

the more interesting question is if expansion is happening at the subatomic level

Insert joke about continuously expanding Americans here.

But that does add an extra mindfuck to the equation. An equation already made up of a minefield of mindfucks.

The universe expands...empty space gets bigger...so what constitutes empty space? Atoms are mostly empty space...they have other forces holding clumps of them together, yeah; but there is also some kind of force acting upon pretty much everything in the universe, even if it's just the weakest of gravitational fields causing the most miniscule of tweaks to the way something moves.

Does the answer lie in chemical bonds? I.e. the earth, all it's organisms, ect, are not subject to universal expansion...nor anything in its atmosphere, I guess...but the vacuum of space that surrounds us is? Or is that also an exception due to the giant black hole that we're spiraling around*?

*Into? I wanna say into. Do astrophysicists, cosmologists, and the like have any solid predictions for how galaxies could end? Or is it a moot point because all the stars burn out first?

 

[Craig234]

The big bang didn't have a location. It created everything. The big bang is all around you. D:

I made the analogy to a balloon and Paul did a good job of correcting it...the rubber is 'spacetime,' and it keeps growing, with everything moving apart. Like if you drew a bunch of dots all over the balloon to represent galaxies...as the balloon expands, everything gets further apart. And the dots get bigger, but we'll pretend they don't...or, wait, should they? Is expansion happening on a galactic level, as well?

I was thinking not, because of the other forces binding all the galactic crap together. And there are of course other forces at play on an intergalactic level, too, but I think the video in the OP touched on that.

That isn't making much sense at this point.

Then again I'm not sure how much we understand 'the big bang'.

And especially anything before the big bang.

I'd think you could reverse objects by time and speed to a 'location' for the big bang.

 

[Jeff7]

That isn't making much sense at this point.

Then again I'm not sure how much we understand 'the big bang'.

And especially anything before the big bang.

I'd think you could reverse objects by time and speed to a 'location' for the big bang.

The Big Bang was the thing that generated the possibility of time and spatial coordinates as we know them, so it can easily mess with people's minds.

 

[Agent11]

That isn't making much sense at this point.

Then again I'm not sure how much we understand 'the big bang'.

And especially anything before the big bang.

I'd think you could reverse objects by time and speed to a 'location' for the big bang.

Space as we know it did not exist then, imagine it as the entire universe exploding with super pressurized super heated plasma, expanding and cooling.

Some interesting stuff if you want further reading here-

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

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

http://en.wikipedia.org/wiki/R-process

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

It's kind of trippy to think about the origins of various matter.

And of course we know little of it, the big bang happened a really long time ago. We have some good guesses though.

 

[phucheneh]

I have mentioned it multiple times before, but for anyone who knows even less about this stuff than I do but wants to learn something...or just likes interesting TV...watch 'Wonders of the Universe.' BBC-produced, airs on the Science Channel sometimes. There's also a previous 'Wonders of the Solar System,' but it doesn't deal with principles that are, well, more universal. Like the Big Bang, formation of matter and different elements, gravity, ect.

Brian Cox takes these complex things, and explains them in a such a simple way that it makes you feel kinda dumb for not knowing it or at least grasping it more fully. Some of it might be a little TOO basic, but it's still interesting. It's kinda like Top Gear meets astrophysics.

 

[phucheneh]

Example clips:

http://www.youtube.com/watch?v=uQSoaiubuA0

http://www.youtube.com/watch?v=NOqR1Csv7yg

They flew the guy all around the world just so he can sit on a rock or something and explain something to you. I utterly luff it. The explanation of entropy, something I don't think the average person really grasps, is beautifully simple.

 

[disappoint]

the more interesting question is if expansion is happening at the subatomic level

It isn't. There is no expansion of space happening for gravity bound objects. Galaxies are not expanding, the spacetime between them is.

 

[phucheneh]

It isn't. There is no expansion of space happening for gravity bound objects. Galaxies are not expanding, the spacetime between them is.

But how do you draw the line?

Aren't the Milky Way and Andromeda bound by gravity?

edit: LOL, I just posted in another thread why people didn't just use Wikipedia before asking silly questions (in that particular case, about a conceived perpetual motion device). Whoops, guess I shoulda followed my own advice.

https://en.wikipedia.org/wiki/Metri...nsion_of_the_universe_felt_on_small_scales.3F

Specifically states that space between the two mentioned galaxies is not expanding.

 

[disappoint]

It wasn't a silly question but I'm glad you found it on Wikipedia. I hadn't read it on there. I learned it watching a Lawrence Krauss lecture.

 

[darkxshade]

A great analogy I once read that made it easier to understand was to think of a balloon as the universe and dots drawn on it as galaxies. As you inflate the balloon, the dots are still where they are but the distance from one dot to another gets farther away from each other. The rate of inflation is this expansion that is happening faster than light.

 

[silverpig]

It isn't. There is no expansion of space happening for gravity bound objects. Galaxies are not expanding, the spacetime between them is.

Well, the expansion of space is happening for gravity bound objects, but it just doesn't matter because gravity overcomes it, so these things stay stuck together.

If the expansion of the universe continues to accelerate, gravitationally bound galactic clusters will eventually fly apart. After a while, galaxies themselves will fly apart, then solar systems, then stars, planets, and people.

If the rate of expansion accelerates with no end, even atoms could be ripped apart.

 

[Cappuccino]

Ask Sheldon Cooper.

 

[darkewaffle]

Neato. I struggled with the galaxies becoming unobservable part for a bit though.

Also if galactic expansion does not occur on a subatomic level, why are we able to observe the redshift in light? Would it not be unaffected? Or is that getting into the whole light is "not quite matter, not quite energy" thing?

 

[zinfamous]

Videos like that are the dark holes of youtube--where the comments are full of intelligent, thoughtful ideas, and can never escape to the rest of youtube.

 

[child of wonder]

I love reading about this stuff. If I could somehow go from age 33 back to 18 I'd pursue a career in astrophysics.