Parallel universes have always been used in science fiction as a great tool, but, as science fiction has a funny way of turning into fact (see Arthur C. Clark’s predictions) having parallel universes is getting very close to being a fact although they are theory at the moment.
But how can our universe (or the one we are in at the moment) exist at the same time as another one? Would the other universe be a mirror image of this universe or would it have the same stuff in it but the stuff act differently from what we are experiencing now?
One theory that supports the existence of parallel universes is the many worlds theory. To understand this it might be best to read one of my previous posts on quantum physics. This theory says that measuring a quantum object does not force it into one state or another. Instead, a measurement taken of a quantum object causes a split in the universe. The universe is duplicated, splitting into one universe for each possible outcome from the measurement.
This means that if there is more than one outcome then those other outcomes are happening in other universes. Even if you don’t take any action and there is more than one outcome, the other outcomes will occur in the other universes.
If you were driving along in your Ferrari (or second-hand rust bucket in my case) and somebody stood in front of you and you managed to swerve and go around them saving the paint on your car, in one other universe your paint would have been scratched and more importantly in one other again you would have run the person over killing them.
On the other hand if you had killed somebody in this universe then you could console yourself, I suppose, that in another universe that person would be alive. Perhaps some of the worst dictators are reading this in the other universes and consoling themselves over the people that they killed or perhaps the ones that didn’t kill anybody are feeling very guilty about the dictators that did?
When you look at the bigger events like wars then you can take this line of thought anywhere really, wouldn’t it be nice to change universes before a nuclear war?
Another disturbing aspect of the Many-Worlds interpretation is that it scares the hell out of our concept of time as linear. Imagine a time line showing the history of World War 1. Normally a straight line showing events going forward is shown but a time line based on the Many-Worlds interpretation would show each possible outcome of each action taken. This is now what would be shown on the time line.
If the many worlds theory is correct then some bright spark in another universe has worked out how to detect other universes and is about to contact us. Perhaps they would wait until we knew a bit more about parallel universes or perhaps we need to know more to make a connection?
The many worlds theory get its theory from the quantum level, but another field of physics believes that the quantum level is not the smallest level. This other area of physics has come up with the idea of parallel universes as well. This even smaller level, smaller even than our quantum toy, has the name string theory.
String theory says that the essential building blocks of matter as well as the physical forces in the universe, like gravity, exist on a level smaller and below quantum level called a subquantum level. These building blocks resemble tiny rubber bands or strings that make up quantum particles called quarks, and in turn electrons, and atoms, and cells and so on and yes even us.
Exactly what kind of matter is created by the strings and how that matter behaves depends on the vibration of these strings. It is in this manner that our entire universe is made up. and according to string theory, this takes place across 11 separate dimensions.
String theory says that universes exist in bubbles that can come into contact with each other, unlike the many worlds theory and that gravity can flow between them. When they come into contact with each other a “big bang” is produced just like the one that produced this universe. So let’s hope that we are not about to come into contact with another universe.
Machines have been made that can detect quantum matter but nothing has detected strings yet. Detecting quantum
matter doesn’t prove that other universes exist as in the many worlds theory it is impossible to detect the other universes. String theory remains also remains theoretical so parallel universes are theoretical.
So what could having loads of universes mean? The first thing that comes to mind are black holes. Black holes suck in matter and even light can’t escape. Where does all this matter go? Well it could go into producing another universe. The matter could come out the other side of the black hole in what some people call a white hole.
This could actually be the start of another universe and our universe could come from a white hole. So as matter is going and producing another universe perhaps one day we will be able to go with it and travel to other universes. The only problem is that you might get a bit squashed to say the least.
If there were infinite universes then if you wanted to learn a musical instrument you could just travel to another universe where you could play that instrument well and learn from your other self. On the other hand you could just do a swap and send your other self back to the universe that your original self came from, though there doesn’t seem much point in that!
I wonder if this meeting of two different “yous” would cause any reactions? Perhaps this is what causes a universe to be started or perhaps the universes dont react at all.
If I had the opportunity I just couldn’t resist jumping around a few different universes and seeing what was going on although if they were all duplicates I think I might get pretty bored.
Parallel Worlds (Everything you need to know)