Tech Talk: Universe or multiverse? | Free – Ashland Daily Press

Reality is something of a subjective topic. It is actually very difficult (at least for me) to decide what it really is. It is abundantly clear to me that it isnt the way we experience it although a good argument can be made that if it is different from what we experience it doesnt really matter. Something along the lines of the question If a tree falls in the woods and no one is around, does it make a sound?

I think of this nature of reality question often as I ponder the nature of the universe. And ponder it is, as there is not much science that can illuminate it directly at this point; only science that hints at the bigger picture. This portion of science is more akin to philosophy than what we know as hard science. Something more like what you would have found 500 years ago as the alchemists worked in their labs far out at the edge of knowledge where there can only be speculation.

The best place to play in this subjective realm is on the scale of the universe where everything is writ large and not that much is actually known. You have to understand that weve only known that there is a universe for a few thousand years and it takes a lot of time to build the mathematical framework to have a hope of understanding something that large. So we are left with educated guesses that arent a lot different than philosophical arguments. The main difference between the two realms is that in science, asking the qualitative questions probably leads eventually to quantitative answers. Or at least should.

So as long as were asking big questions lets start with a doozie: Is there only one universe? It turns out that there are a number of scenarios where it is possible that there are many of them.

The simple version of this comes about if we postulate that the universe is infinite and that stuff is spread out evenly (as it appears to be). If it is, we can only see so far out because of the age of what we take to be the universe and the fact that light goes fast but at a finite speed. The universe as we know it is about 13.8 billion years old, give or take. That means you can only see to 13.8 billion light years out as it takes light that long to get here (by light, I mean anything that acts like it, visible or not). If there are other clumps of stuff out past that, we cant know that at this point so, for practical purposes, there would be multiple, disjoint universes. At some point, the light from these things would reach us and wed see it likely as an expanding universe because wed start seeing further out and it would be hard to tell the difference between expansion and just seeing further.

So what might be said if the universe is not infinite? A finite universe is what science is pointing to at this time. Current theories assume that our universe started out in space (in our 4 dimensional universe, it isnt helpful or even useful to ask what space would be at that point). At some near infinitely small spot in space, the energy there changed to matter (matter and energy are the same thing and entirely interchangeable) creating a huge explosion with things moving faster than light in the first fraction of a second (you can violate the laws of physics if you do it fast enough). This state of movement has been dubbed inflation and happens so quickly that the resulting fireball spreads the stuff of the universe out reasonably smoothly except for the randomness that happens (things are mostly random) which would give rise to small clumpiness to the results. We see these results today as the cosmic background radiation and it has been mapped in very fine detail and agrees with theory on this so it is quite likely that inflation is how we should look at our current state of the universe. It would, if you could get outside it, look essentially like an expanding balloon.

The thing is, if ours could come into existence because of probability, then there really isnt any reason that another one couldnt come into existence by the same mechanism. If it did, we couldnt see it because itd be racing the other way faster than we could ever catch up to it. Along the same lines, if you can create two of these, why cant you create any number of them? In fact, given the finite probability of it happening at all, we should be creating them all the time and if thats the case, our particular universe would only be one of countless others forming constantly, none of which could see each other.

This scenario would also help physicists with a sticky problem: There is a branch of physics that is an attempt to describe on one equation all of physics called String Theory. This is something of a Holy Grail of physics for some time now. The trouble with it is that it is a multi-dimensional equation (more than our four) and has an astronomical number of equally valid solutions, not just our particular physical laws. If there are a whole lot of other universes, then it could be possible that each is a separate solution to the problem a valid set of physics that is different than ours. This would neatly solve this puzzle.

There are other possibilities involving things like quantum physics and parallel sheets of universes operating in separate dimensions all of which satisfy some set of curiosities or other. In fact there appear to be more reasons why there should be multiple universes than there are suggesting we would be living in the only one.

Things to ponder as you look up into the night sky. Are we alone? Are we even what we think we are?

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Tech Talk: Universe or multiverse? | Free - Ashland Daily Press