Sunday, January 16, 2011

You Can't Get Here From There.

This probably qualifies as a brain fart, but...

There's an article in today's NY Times that kinda blew my mind.  Much of it relates to things I already know about...or at least things that I'm aware of. In my case, that means I'm perfectly willing to accept certain scientific principles without understanding the science behind them.  I'm familiar with some of the results of the Theory of Relativity, but the science behind it leaves me in the dust.

So, anyway, I'm familiar with the fact that when I see a speck of light in the sky, I'm seeing a bit of light that "happened" a few years or a few thousand years ago...depending on how far away it was when it happened.  I'm actually seeing living history right in that moment.  That qualifies as awesome and amazing, but it's not at all incomprehensible.

The article goes on, however to talk about how the universe is expanding and that the speed of that expansion is not a constant.  In fact, the speed is constantly increasing.  Somewhere, there are distant galaxies that are getting further and further away from us and they're doing it quicker and quicker.

And then, it got to the part that floored me:
"Although nothing can move through space faster than the speed of light, there’s no limit on how fast space itself can expand."*

The result of that little concept is that eventually, some galaxies will cease to be visible from Earth -- not because the lights go out, but because they'll have gotten too far, too fast.  I've accepted that some galaxies may be so far away that their light hasn't reached  us yet, but this means that some distant galaxies are moving away so fast that their light will lose the race to ever arrive here.  They'll always be moving away from us faster than their light is traveling toward us.

The article goes on to wonder how future generations (really, really future, since none of this is going to happen in the next few months), will perceive the universe.  Since they'll look out and see nothing but a void in the distance, will they believe the "primitive" records left to them from the 21st Century?
*How does that work anyway?  Are some parts of space expanding while others don't?  Assuming gravity is holding an individual galaxy together as a unit, and assuming that the space between two galaxies is expanding at a speed faster than light, doesn't it follow that the two galaxies -- and every object within them -- are moving away from each other at a speed faster than light?

This makes my brain hurt much in the manner of the question of God being able to make a rock so heavy, even he can't lift it.


Janiece said...

Nathan, if you're really interested in this, may I suggest Sean Carroll's book, From Eternity to Here? It's written for the lay person, and Dr. Carroll explains the phenomenon you describe (certain sections of the universe expanding faster than others) as a result of some sections of the universe being "lumpy." And it TOTALLY MADE SENSE.

Steve Buchheit said...

Then there's the theory to explain that lumpiness, in that the universe is expanding like a series of bubbles. And the space within those bubbles is expanding faster than what is on the surface is expanding (function of volume over linear mapping). Just more proof the world is stranger than we think.

Nathan said...

I'm willing to be educated, but I can't wrap my head around the concept that Object A can move away from Object B faster than the speed of light...yet not be moving faster than the speed of light.

I'm a black hole. I'm where concepts go to die.