Imagine a physicist sitting in a cage with a gun aimed directly at his head. Every few seconds, measured direction of the spin of a particle in a random room. If the spin is directed in one direction, the gun shoots and physicist dies. If the other, it is heard only a click sound and physicist survives. So, the chances of survival of physics - 50 to 50, right?
Things can not be so simple if we live in a multiverse - that is, except our universe that we call home, there are many others.
With a script with a physicist and a gun begins the famous thought experiment called 'quantum suicide', and this is one way to try to understand whether we are living in one of the many (and potentially infinite) universes.
This thought experiment is based on quantum mechanics and the idea that a single objective reality does not exist. All that we see around us, it is only one of the possible configurations of all the probabilities of what will happen or that event. One interpretation of quantum mechanics is that all the other sets of probabilities may exist in their own separate universes. So if you follow the thought experiment, given this interpretation, when you measure a second particle, the universe is divided into two, each of which is a possible variant of accomplishment of events: in which the physicist alive and in which the physicist died.
Its survival is now associated with quantum probability, so that he seems to be alive and died at the same time - just in different universes. If the new universe splits each time a particle is measured, and the gun or shoot or not, in one of these universes eventually physicist survive, say, in the course of 50 particle measurements. Compare it can be thrown 50 times in a row coin. The probability that the 50 consecutive falls tails, is extremely small, but it is - a chance to zero.
And if that happens, the physicist will understand that the multiverse is real, and in the case - in the experiment described - physicist truly immortal, since the gun never fired. But he will also be the only person who knows that these parallel universes exist. Yes and how many physicists will have to "spend" to find out for sure.
However, there are other, more reasonable version of multiple universes, which are backed by mathematics and potentially verifiable.
"For some people, parallel universes - it's like jumping through a portal to another world or something like that - says Matthew Johnson, a physicist at the Perimeter Institute. - But this is different. "
Actual observed evidence for the existence of multiple universes will be difficult to find, but not impossible. So physicists are planning to do it.
Versions of the multiverse
In fact, multiple theories of the universe, there are quite a few, and the multiverse of the thought experiment with the "quantum suicide", where every possibility becomes a reality, one of the most radical.
A physicist at MIT Max Tegmark offers a theory of multiple universes split into four different types, it was convenient to think.
We will focus on the first level of the multiverse - this version is easier to understand the other. At the first level, we are also quite good chances to find evidence that will prove that the multiverse is real.
Multiple universes are derived from mathematical projections of existing theories and first-level multiverse predicted very respected and weighty idea in physics: inflation.
What do we mean by "the universe"?
To understand the idea of multiple universes, you first need to define what we mean when we say "the universe." Our definition of "universe" is not just me, for example, when we invented the first telescope, they look out into space, and know that the stars are not attached to the sky on the nails, and the Earth is not the only one in space.
But the universe is much bigger than we can see with a telescope, Johnson says. Our universe is a sphere of light, which was enough time to get to us. If we wait a billion years, we will see even more and our concept of the universe will turn again, says Tegmark.
Someone standing on the planet for billions of light years away from us, will have a completely different picture of the "universe", based on how much light fell on his planet.
We did can not reach to those other bubble universes, by definition, because there is no way to move faster than light. Although we do not see them, physicists believe that they were born the traces can still be found.
Where is the proof?
Inflation The idea is that at the time of the birth of our universe went through a period of rapid expansion (immediately after the Big Bang), when the nanometer space suddenly exploded to 250 million light years in less than a trillionth of a second.
After the start of inflation is never completely stopped. In some regions of space-time, it stops in their areas of space are transformed into bubbles like the universe that we see around us, but in other places the space continues to expand. If the expansion is infinite, and many have believed that new bubbles are formed continuously universes. It remains a bubble trail. We are drifting through space-time foam Jacuzzi universes.
Again, there is no way to contact the other of these bubble universes, because we can not move faster than light. But theoretically, we can prove that they exist. And here's how.
When our bubble universe was formed for the first time, it is possible that she ran with other bubble universes, which are formed around our. It is unlikely that we are still close to them, as the continued expansion of space-time takes us farther and farther away.
Nevertheless, the impact of early collisions could let the ripples on the cosmic microwave background (the heat left over from the Big Bang). Theoretically, we could notice that ripples with telescopes. It would have been bleached disc - like a bruise on the body of the microwave background.
Jones is looking for such "bruises", but a lot depends on how quickly there were other bubble universes and how many of them could ever be. If the bubble a bit, we could do with them not to run.
Planck space telescope is currently listening to the heavens in search of evidence of such collisions with other universes.
Multiverse within the LHC
Different physicists have different theories of the multiverse. This version comes from string theory and the idea of the existence of many other dimensions to which we simply do not have access (in a situation in which McConaughey hero hit the "Interstellar" movie). Some physicists believe that parallel universes are hiding in these additional dimensions.
This idea of a multiverse is also verifiable.
Physicists will look for microscopic black holes at the Large Hadron Collider, which has earned one of these days. At the LHC, it is impossible to produce a black hole that will be dangerous, but, according to this theory, it is possible to create a microscopic black holes that would instantly evaporate. The presence of black holes would mean that the gravity of our universe seeps into the extra dimensions.
"Because gravity can leak from our universe in the extra dimensions, such a model can be checked to find miniature black holes at the LHC - told physicist Mir Faisal. - We have calculated the energy, which can detect these black holes in the gravity rainbow. If we find black holes at this energy, we know that as the theory of gravity of the rainbow, and the theory of extra dimensions - both are true. "
It would be convincing evidence for string theory and parallel universes, and would also help to explain why gravity is much weaker than the other fundamental forces.
However, no serious evidence yet. Only doubt.
"I believe only in what is confirmed by concrete, verifiable by experimental evidence, and the concept of parallel universes that can boast exactly", - said Brian Greene, a theoretical physicist at Columbia University.
The problem is, says Johnson, that physicists are removed from the philosophical discussions of multiple universes. Some people just want to test the idea. Others take radical and untestable theories. Tegmark says it will try to experiment with quantum suicide, when the old and infirm. But let's hope he just joking