Thursday, July 12, 2007

Follow-Up on Universe-Talk

Finally something interesting. Somebody qualified is proposing that the data has been poorly interpreted: the universe may actually be contracting, not expanding. This is a wonderful inversion, and it makes some sense -- if you admit (as astronomers will) that there is no non-relative point in the universe, then it seems perfectly reasonable to interpret the apparent widening gap between us and the next nearest galaxy cluster as evidence that we are hurtling inward a little faster than they are (thus increasing the gap).

The problem that anyone with a dab of intuition will raise is that the gap appears to be increasing uniformly in all directions. Interesting problem. But it is not more or less problematic in the scenario of a collapsing universe or a contracting universe than it is in the customary view, the expanding universe. I had a hard time figuring out on "the internet" whether scientists think galaxies are expanding or contracting, but this picture makes me think "contracting":


Looks like water down a drain to me; and if happens at the galactic level, I don't see any reason that it couldn't happen with the entire universe. Further, why do we tend to believe our observations at the fringes of our technological capability more than those we are sure about? It is certain that our solar system is not expanding. Nor is our galaxy. Nor, even, is our "galaxy cluster." It's at the level of between-galaxy-clusters that the expansion is supposed to be occurring. Really? I don't know about red-shifts that much, but is it possible there's some kind of distortion happening?

Here's my best guess: the number of black holes increases (naturally) with distance... as light passes a black hole and curves, it decreases in speed. Thus, cosmic objects observed farther away will not arrive at the speed of light, but slower. The effect decreases as we observe closer objects. A weak pictorial representation:


If nothing nearby is observed to be expanding, is it really probable that something that isn't happening here is happening way out there? Umm... sorry about that last sentence. My post below on heresy and blasphemy is better.

8 comments:

brian said...

Alan Watts would be hot if he'd get on the bench press three times a week.

Sorry...I'm reading Dharma Bums and it has made me very skeptical about people that live on House Boats.

Casey said...

Being skeptical about people that live on House Boats is like being skeptical of wandering parable-tellers who wear sandals, or about men who sit under mangrove trees for ten years, or whatever. Or about frisbee golfers.

brian said...

What does water going up the drain look like?

Wishydig said...

Usually muddy and full of hair.

Cathy said...

Casey. I'm appalled at the lack of seriousness with which your fellow bloggers received this theory.
You need to appeal to higher authorities. If God isn't available - try Hawking.

brian said...

Slaughterhouse-Five is really starting to freak me out--The Tralfamadorians might have it right...

PS Good luck at the wedding.

"Brian" said...

Wait. We ARE the Tralfamadorians...while we're sleeping.

Justin said...

OK this is a bit hard to explain without a huge amount of info. When it is said the universe is expanding or contracting, there is no common center involved in this. There is no edge or center to the universe. If you travel in one direction as far as you want you will never run out of galaxies and stuff. There is no "inward", because it implies a direction towards a point that doesn't exist.

The universe is expanding or contracting in volume because the space in it is expanding. The universe is either gaining or losing space itself. Gravity is stronger than this effect is when it comes to shorter distances. A galaxy is bound together by gravity. At the distances involved in a galaxy, gravity outweighs the expansion and pulls everything together so the expansion of space has no net effect. But at distances found between clusters of galaxies, the expansion of space is stronger than gravity, so other galaxy clusters seem to be moving apart because more space is actually appearing between them. They aren't flying off into nothing, nothing is actually appearing between them. (That's a fun one to imagine.) I digress, space truly isn't "nothing". But the idea is, it's a small effect that over short distances is unnoticeable because more powerful forces outweigh it, but over long distances it really adds up.

The best way to visualize this is to take a balloon, blow it up a bit, and put some dots on it with stickers or felt tip pens or something. Then if you blow it up some more, notice the dots get farther apart. Let out some air, and the space between reduces. The dots are galaxies, the balloon is space in the universe. As the universe gets bigger, the density of things in it gets less, if it contracts, the density goes up.

As for light over distance, the speed in space doesn't change, if it gets carried into a black hole it goes down the drain into a singularity and that's that. However, light does curve around large gravity wells. This is a known effect, and is compensated for at very long distances. So if you had a straight shot view of a galaxy a long way away, and another galaxy seen because the light curved around an object, the curved path could have the light reach us at the same time but the object is closer, the light just took a longer path to get here.

As for redshift, it's similar to the Doppler effect. If something is coming closer, the the frequency goes up, if something is moving away, the frequency goes down. (The reason the tone of a vehicle goes up and down as it goes by.) Galaxies at significant distance all have a growing redshift, this means that visible light is growing in wavelength, turning into infra red, which generally means something is moving away from us.

The argument made in this paper is that if we live in a closed Friedman universe (note the if) then it's possible that redshift works in reverse at long distances and therefore having the reverse meaning. So if we live in an expanding universe we are seeing what we should be seeing, but we live in a contracting universe we are also seeing what we should be seeing. Isn't science fun? :)