Thursday, 2 August 2007

Someone else in the universe already posted this but in a galaxy far far away

I would like to start off by saying I know nothing about physics apart from the excess of Sci-Fi I watch when I was younger and the random conversations I have with my physics friend Bob. Nevertheless I do like it despite it never making any sense. As a biologist there is a reason behind just about everything (ie evolution has shaped it all). It unsettles me when I don’t know why something is the way it is (so most of immunology then). Before reading the rest of this you need to assume a couple of things about the universe for what I am going to say to make sense, they are apparently correct but what do I know. Firstly space is infinite or extremely large (according to Prof Max Tegmark evidence for a small universe or donut shaped one is weak and he believes the universe is infinite) and secondly that matter is evenly spread out throughout space (not just clumped around us).

For the first part we will say our universe is the part of space we can see (the outer edges are determined by the age of the universe and how fast light it, as it gets older we can see more because more light has had time to travel to us). This is also called our hubble. Level I multiverse or parallel universes are simply hubbles out there that are like ours (and many more not like ours). If space is infinite all arrangements of matter that are possible exist! I like to think star wars and LOTRs obey the laws of physics so they could exist. Everything in level I has the same laws of physics as our universe because it is only an extension of ours. Out there, there are more hubbles just like ours but very far away. One estimate says one just like ours in every way could be 10 to 10118 metres away! Closer will probably be some hubbles that are very similar to ours but slightly different. Their will be an infinite number of all hubbles because space is infinite (from my understanding). I think these estimates are far to low and don’t take into account some things but it gives you an idea that even a low estimate is amazingly far away.

That was the easy stuff. Level II multiverse (or parallel universes) is less accepted than level I but still apparently explains a lot of things in physics. It helps biologists in their fight against pro intelligent design arguments. It is where many multiverses (same as in level I) exist but each multiverse is separate and has different physical constants or number of dimensions. This explains why our universe just so happens to be able to support life – it isn’t custom built to support life but is just one possibility of how the universe works. We have 3 spatial dimensions and one time dimension but if we had more time dimensions events would be completely unpredictable and if we had more spatial dimensions atoms would be unstable. If the mass of an proton was slightly larger it would decay to fast for molecules to be made so obviously nothing for evolution to act on and life to form. Each multiverse is still infinite within a sea of inflating infinite empty space (don’t ask me how you can have infinite space inside infinite space, because I just don’t understand). We can never travel between these multiverses even at the speed of light because they are moving away from each other faster! That sounds like science-fiction to me.

Level III is the one that interested me the most as a child (yes I have always been this way, Egon Spengler was my favourite Ghostbuster…need I say more). Every choice means you have to choose a path to follow. But in level III all outcomes exist but the other choices exist in another universe and not in space as we know it but ‘elsewhere’. However the choices I am talking about take place on the quantum scale! This goes back to Schrödinger’s cat (if you don’t know what it is, it would be best to look it up before continuing). From what I understand all it means is all states or positions exist until someone observes what state it is in. So something is both on and off or dead and alive until someone checks. This is called a superposition. An alternative theory is that both do exist but new universes are created to accommodate the other possibilities. It is like rolling a die that is only governed by the rules of the quantum world and not the overall rules of the universe. Because it is only on the quantum scale the outcome is completely random (from what I understand). According to level III multiverse it will not land on a 1 or a 2 or a 3… but will land on all six values at once. How; each one exists in a different universe, easy! And we thought biology was screwed up, at least it usually makes some sense. The outcome of level III is the same as for level I and II, more universes most slightly different from ours. The difference is how it is made.

Level IV is the one I feel least confidence about explaining. It is there to explain why our universe works under a set of specific mathematics and not controlled by other models. Universes that work using different mathematical models may exist outside our spacetime and work in completely different ways. They work using different laws of physics even more different to ours than by multiverses in level II. Level I, II and III were created by the same big bang. Level IV exists outside spacetime and will have had there own starting events but more level I and II (and III) could have been created by other big bangs as well. In level I and III you will have a Doppelgänger but in II and IV space will be so radically different you will not. Well I think you might if a parallel universe created in level II or IV is very similar and works off the same rules as ours.

All of these theories do make some predictions so they no longer lay in the realms of metaphysics but of real science. So in the next few years we may see some of these confirmed or rejected as fact. Whether they exist will have little impact on our lives. Will it comfort you to know someone out there in the infiniteness of space is in exactly the same situation as you or better of, or in a worse situation! I don’t think it will keep me awake at night. Nothing we can do will have an affect on them. I only discuss this because I find it interesting. But I find most things about our world its place in the universe interesting. We didn’t evolve to understand things like this but we did evolve to ask question about our environment.

For more information see Scientific American special report on Parallel Universe by Max Tegmark or his website:

http://space.mit.edu/home/tegmark/multiverse.html

this has more references.

Please ask me questions, no promises I can start to answer but I have thought about the topic for a while and would like to hear your thoughts and see of you have the same questions as me.

8 comments:

Menelaos Symeonides said...

Lucy has to read this post, I think she will have some very interesting views on it.

I like the fact that science fiction is turning into scientific theory, it makes star trek seem like slightly less of a waste of time. I don't think that it is very easy to explain most of the things in your post without using mathematics but you have done pretty well!

Is there ANY way to travel between multiverses of whatever level? I am talking about things like black holes because the classical science fiction idea is that you can travel vast distances within our spacetime (which according to the things you explain here includes up to Level III multiverses) using black holes, so is this based on any actual science or is it pure fiction?

James Lloyd said...

thank you. good question can you travel between any of these. if you could travel far greater than the speed of light which people dream of but many think is impossible we could visit other level I universes. these are in our space time and are simply far away. assuming the universe is infinite (which may be a big leap) it is going on a road trip to somewhere else but the country is so large the place starts to repeat themselves. like is england was infinitely large you would keep driving and find another york almost exactly the same as ours with the same people. it is that idea as level I. problem is space is so large and them times that by infinitely and you wouldn't be able to know where you are going or have a map. so traveling to one may be possible but finding one to head for i think is even more difficult.

i think level II would be out of our grasp becasue each level I multiverse inside it is somehow infinite but if you break out of it you still have massive rapidly expanding space to travel.

for level III they are somewhere but where? do they exist all around us as invisible small universes. i really dont know how you could travel to one of them. first step would be finding them if they exist.

hope that tries to answer your question. any more please.

Lucy said...

This kind of stuff really messes with my head, I agree with some things - like the level I multiverses must exist, but I still don't think that, even if the universe is infinite, you would find an identical one anywhere. I mean if you think of all the events that would have to happen, over millions of years exactly the same, and you could multiply all the probabilities together of that happening, I suppose technically it would be POSSIBLE (ie it wouldn't be a probability of 0), and in a universe of INFINITE possibilities, it would have to exist... so the theory works, yet I still don't see it as likely.

I guess the problem I have with it is that the theory only holds GIVEN that the universe is infinite, which is far from a given. These theories are making predictions providing that other uncertain things are true; I think that people would need to prove the underlying principles (though don't ask me how you'd prove the universe was infinite) before they can start making these kind of theories.

Also I read up on the cat thing and I just don't see what's going on with that. So if I checked on this cat and found him dead then that's that, but if instead I'd decided not to look in this box, he'd be sat there, both dead AND alive?! HOW does this kind of theory make ANY sense, something cannot exist in two mutually exclusive states at once!

James Lloyd said...

i think there are many who think the universe is small or a donut shape. but this person whom article i read thinks the universe is infinite based on some sort of radiowaves reading or something. i dont understand it. but if it is infinite and matter is evenly spread then all possible matter arrangements must exist as infinity times any number is still infinity.

i always say to my physics friend bob his subject makes no sense. the cat thing is just one of many examples. the cat is trying to explain changes in subatomic particles (so what makes up protons and electrons etc) and i dont understand that very well at all (i wish i did) and the idea is along the lines of if something changes both states exist (the superposition) until someone observes it. then it randomly choices one. level III tries to explain this by it is not random but both do exist when the change happens but each is in a different universe. hence more universes very similar to our own as only subatomic features are changing. so think of it perhaps as an electron orbiting the atom can move to 1 of 2 places. in level III in our universe it moves to one place but in another universe created it moves to the other.

i hope that tries to explain it better. any more questions please ask.

Menelaos Symeonides said...

Lucy, I share your skepticism about the multiverse theories but I think there is a whole lot that we cannot even begin to understand unless we know the mathematics behind it. I have no idea how anyone can say whether the universe is donut shaped or infinite, but if those people are out there saying things like that and haven't been locked up yet, they must have some sort of rational reason to believe so. I don't actually understand how people get funding for this sort of research since what they keep concluding is that their research basically does not concern anyone... quite bizarre.

Anyway, about the quantum thing, this one is a lot more tangible, and is not at all as nonsensical as it sounds. Watch this video, hopefully it will convince you that it isn't made up :P

http://www.youtube.com/watch?v=DfPeprQ7oGc

James Lloyd said...

really good video. i agree it seems weired how people get funding for this but humans love to ask questions and explore, even if in the short term or not even the nearish long term these things wont help gain profit one day the understandings may. a lot of biological research perhaps has little immediate benefit but one day it may. the pure side of things may one day help the applied.

Catarina Vicente said...

God that is confusing... I wish I could have a portable physics expert to explain all those things (or James around more times...). I guess the problem with this sort of area that I at least don't master, is the fact that I have no idea if statments like 'the universe i donut-shaped' can be compared to 'nucleotides can be A, T, C or G' or something of the kind 'Eating DNA can be dangerous for you'... We don't understand the maths, so I reckon that only much reading and discussions with sensible people who can actually understand it is the only way of having a sensible view of the subject?

James Lloyd said...

what helps is a approach physics as a hobby because i happily dropped it as soon as possible! because i couldn't do the maths or picture the basics but stuff like this is more about philosophy in a way. Metaphysics is the term for physics ideas that cant be tested so need to be in the realm of philosophy. as i said this is perhaps not metaphysics but i treat it like anything i will never fully understand such as politics or most things about life. i only worry about truly understanding molecular biology or the origins of life.