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Nothing Special

Entry 1436, on 2012-09-10 at 21:22:00 (Rating 1, Science)

In the past many people have wondered about why certain numbers and certain combinations of numbers are what they are. For example, there seemed to be a law establishing the distances between the planets of the solar system, and there was thought to be something special about the distance from the Earth to the Sun.

The famous astronomer, Johannes Kepler, wondered why the Earth is exactly 93 million miles from the Sun? (it isn't) Why was that distance so special? There is the observation that the Earth is at just the right distance so that its temperature is ideal for life here. But that could apply to a range of distances inside the "Goldilocks zone" and there are many attributes of the planet itself which affect its temperature more than a simple difference in distance.

There is also the fact that life can adapt to a range of temperatures (although that range is still fairly narrow) and life here has adapted to the temperature we have, making the idea that the distance is ideal a sort of back to front way of looking at the phenomenon.

So Kepler was really looking for a reason which didn't exist. There is no reason that the distance just happens to be 93 million miles. That's just what it is by chance, and the untold (estimated) trillions of planets in our galaxy all orbit at different distances. If our planet hadn't been in the Goldilocks zone (not too hot and not too cold) then we wouldn't be here to wonder why that distance is so special.

So it's important not to look for meaning or significance where none exists. Humans are very good pattern finders, so good that they often find patterns where none really exist. That's why so many people believe in astrology and ESP and alien visitors and the supernatural: they are seeing patterns where none really exist.

But are there areas in modern science where a pattern is being searched for where there is no good reason to think one should exist? What about the fundamental constants which govern the forces and other basic attributes of our universe? Scientists have wondered for many years now why various constants, such as the total mass of the universe, the number of dimensions we experience, the relative strength of the electromagnetic and gravitational forces, and others are what they are. If any of these numbers were much different the universe wouldn't be suitable for life. Surely there must be some explanation for this bizarre phenomenon.

Maybe not. Maybe it's like the distance to the Sun. Maybe the numbers had to be right for life or we wouldn't be here to wonder about the numbers!

There is one difference though. We think (with high certainty) that there are a lot of planets in the universe. Many have been discovered by Earth-based telescopes and the Kepler mission. There is good reason to think there might be trillions in our galaxy alone. So amongst all those planets it would be incredible if there weren't some which were suitable for life. But can the same argument be used for universes?

As far as we know there is only one universe so the same argument doesn't seem to apply. But is there really just one?

Clearly any theory which concludes there are many universes is currently highly speculative but the idea does seem to be gaining increasing acceptance. When string theorists started examining the way 11 dimensional space (as required by string theory) could be configured they gradually found that more and more universes should emerge. First it was a few, then hundreds, until now there is an estimate that there should be 10^500 different universes!

That number is so huge that it is impossible to convey. It's 1 with 500 zeros written after it. Compared with that the number of grains of sand on Earth is nothing. The total number of stars and planets is nothing. The number of particles in the whole universe is nothing!

So if this particular prediction of string theory is right and if string theory itself has any validity and relevance to the real world (many experts refuse to even admit it is a theory and describe it as "not even wrong") then there is nothing to explain: out of the incomprehensibly large number of universes out there we live in one with constants which have the "correct" value because we couldn't exists in a universe with the wrong numbers and we couldn't ask the question.

Science progresses by testing theories so the question obviously becomes: how could we check if there are other universes? If we could detect even one other universe then the string theory multiverse theory starts looking good. After all, if there are two universes then why couldn't there be ten, or a thousand, or a million, or a trillion, or a quadrillion quadrillion quadrillion, or even a really big number of them?

Believe it or not, it is possible to perform this detection. If multiple universes exist they should interact or "collide" occasionally and this should be detectable by looking at the background radiation of the universe on a large scale. So far there is no really compelling evidence of these collisions but there are various interesting phenomena which are worth pursuing.

It's really quite intriguing. First we thought the Earth was unique and occupied a special place, then we thought our Sun did, then our galaxy, then our universe. Maybe all of these ideas are wrong. Maybe all of those things are just one amongst countless (maybe even infinite) numbers of others. Maybe there's nothing special about anything.

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