Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Does parallel universe exists ?

  1. Jan 8, 2010 #1
  2. jcsd
  3. Jan 8, 2010 #2
    Last edited by a moderator: Sep 25, 2014
  4. Jan 8, 2010 #3
    Re: Does parallel universe exists ??

    Although Everett's http://en.wikipedia.org/wiki/Many-worlds_interpretation" [Broken]is considered mainstream, it's not the only one out there. In fact, a poll taken during the Quantum Mechanics workshop in 1997 revealed the Copenhagen interpretation was more widely accepted, although leading physicists have said for the last 20 years it should not be considered primary, and there are other theories, including MWI and decoherence, which explain it better.

    Here's a http://en.wikipedia.org/wiki/Interpretation_of_quantum_mechanics#Comparison"of the most common interpretations.
    Last edited by a moderator: May 4, 2017
  5. Jan 8, 2010 #4


    User Avatar
    Science Advisor
    Gold Member

    Re: Does parallel universe exists ??

    Detecting parallel universes is the issue. We have not, and probably never will. I rate that hypothesis roughly equivalent to the tooth fairy.
  6. Jan 19, 2010 #5
    Re: Does parallel universe exists ??

    how can you say that much surely that parallel universe are just like a tooth fairy ,it may be possible,because scientists confirmed that time travel is possible, but they are not getting the way ,how it can be done? that's the main problem.
  7. Jan 19, 2010 #6
    Re: Does parallel universe exists ??

    So what is exactly parallel universe?

    Here I claim that there are gazillion of them. Prove me wrong.

    Or, here I claim that there is none. Prove me wrong.
  8. Jan 19, 2010 #7
    Re: Does parallel universe exists ??

    once look at this link-
  9. Jan 20, 2010 #8
    Re: Does parallel universe exists ??

    Hmmm, parallel universes, this is a very complex topic, but I will try and describe it as clearly as I can.

    At the moment, most scientists believe in 4 'levels' of different universes, or multiverses. Each level is a different scenario of how we think parallel Universes could arise and what they would be like. I'll just go through them one by one, but won't bother much with Level II and IV multiverses because they are nasty.

    Level I

    Note: In this, Universe applies to all the little universes (such as our own) put together.

    Level I multiverses are based around the idea of 'Inflation'. Inflation is what we believe stopped all the matter created by the Big Bang recollapsing into itself moments after its spontaneous creation due to it own titanic gravity. I won't explain inflation here, that would take ages, just think of it as the heat of the Universe making it expand very quickly. Anyway, what many scientists think, is that inflation blew apart all the little 'grains' of early Universe that were starting to condense into smaller areas of space such as our own. This left all the little 'bubbles' of space stranded far away from each other, seperated by billions of light years worth of void. I'll try to explain it in a diagram. We are area 'A' and there is another area 'B' which got seperated from us in the moments after the big bang.

    <-- area A, 13.7 billion light years radii -- > <- 50 billion light years gap - > <-- area B, 13.7 billion light years radii -- >

    As the diagram above shows, both areas A and B can only see things in a sphere, radius 13.7 billion light years around themselves (Yes, I know earth isn't the centre of our area of space (or universe), but because physics is broken, every point in our area of space/universe looks like the centre of it). But, due to inflation there is a gap 50 billion light years wide in between the two areas, which means neither area will encroach on the other, or be aware of the other's presence for another 50 billion years. Effectively, they can be thought of as different universes.

    Seeing as matter can pop out of nowhere in a vicious way, we can effectively think of the number of these small, seperate universes as being infinate. You might think this would lead to an infinate number of different universes, but, quantum mechanics tells us that there is only a finate number of ways of putting together all the atoms in our universe, an enormous number, yes, but not an infnate number. This means that somewhere, approximately 10^10^115 metres away, there is an exact copy of our Universe. We can then lead this on to say that anything you can think of the Universe being like, will exist. Which means that there could be a universe where life took an extra 1000 years to develop, but apart from that is exactly the same, so if you could travel there, you would essentially have gone 1000 years into the past.

    Of couse, finding out which universe you want to go to, and how to get there may be impossible, but nevertheless, the chances of such a scenario as described above being reality, are pretty high.

    Level II

    Level II multiverses arn't worth talking about much. Essentially, a level II multiverse scenario is if the Universe (There's only one main universe for this unlike Level I) has multiple 'buds' of smaller universes, formed from minature Big Bangs, leading off it via wormholes. If you found a way of travelling through wormholes you could go to them, but physicists expect that in bud universes, there is a good chance of universal constants being different. For example, gravity could not exist, or magnetism could be strong enough to tear us apart, so you wouldn't want to go to them.

    Level III

    Our current idea of what Level III multiverses are and how they form was first thought up by the American scientist Hugh Everett III, he invented the 'Many Worlds Interpretation' of quantum mechanics which essentialy states that whenever a decision is made, a two or more new realities form, each accomodating for each possible outcome. This would lead to an incredibly large number of parallel Universes, seeing as even the slightest movement of an electron could be considered a decision.

    The famous 'Schrodinger's Cat Box' thought experiment captures the essence of a Level III multiverse rather well. Whilst the box is closed, only 1 reality exists, the moment the box is opened it splits into 2 realities - one in which the cat is dead, the other in which the cat is alive. Of course, this is very simplified but it does explain the basics.

    Level IV

    Level IV Universes are aslo not worth talking about seeing as they are the least likely. Essentially the theory behind it is, that each mathematical function has a Universe which was created by it. In a way, Level IV and Level II multiverses are similiar seeing as universal constants would be different and probably kill you if you tried to go there.

    And that's all I'll write for now, I'm sorry if it sounded like a science lesson, but I hope you enjoyed it.
  10. Jan 20, 2010 #9
    Re: Does parallel universe exists ??

    (c) Max Tegmark
  11. Jan 20, 2010 #10
    Re: Does parallel universe exists ??

    Nop, this is not Tegmark.
  12. Jan 20, 2010 #11
    Re: Does parallel universe exists ??

    Tegmark just invented a theory of Level IV multi-verses, a theory which most scientists think of as nonsense.
  13. Jan 20, 2010 #12
    Re: Does parallel universe exists ??

    I would say, currently a minority of scientists have accepted MUH. Once you accepted MUH (and MWI) the next step (Level IV) is unevitable.
  14. Jan 20, 2010 #13
    Re: Does parallel universe exists ??

    Not if you leave 50 bly gaps, between Hubble volumes.
  15. Jan 20, 2010 #14
    Re: Does parallel universe exists ??

    10^10^115 is a lot bigger than 50bly.
  16. Jan 20, 2010 #15
    Re: Does parallel universe exists ??

    Yes it is. Anyway, I think that, that estimate relates to one HOMOGENOUS universe, which is spatially infinite or simply big enough. You can search for identical arrangement of matter for volume of any radius, smaller or bigger than Hubble radius.
  17. Jan 21, 2010 #16
    Re: Does parallel universe exists ??

    i really enjoyed it ,it's good one
  18. Jan 25, 2010 #17
    Re: Does parallel universe exists ??

    Wikipedia's definition of time travel is this :

    Time travel is the concept of moving between different points in time in a manner analogous to moving between different points in space, either sending objects (or in some cases just information) backwards in time to a moment before the present, or sending objects forward from the present to the future without the need to experience the intervening period (at least not at the normal rate).

    Please elaborate on how such an impossible feat can be achieved. Is time travel actually confirmed as possible?
  19. Jan 26, 2010 #18


    User Avatar
    Science Advisor
    Gold Member

    Re: Does parallel universe exists ??

    So wikipedia has an opinion? I do not find that compelling or convincing.
  20. Jan 26, 2010 #19


    User Avatar
    Science Advisor
    Gold Member

    Re: Does parallel universe exists ??

    There is no compelling observational evidence of parallel universes. Until such evidence is produced, it is pure fantasy. Pardon my hard core skepticism.
  21. Jan 27, 2010 #20
    Re: Does parallel universe exists ??

    Parrallel universes exist? No! Im of the opinion they've hit a wall, run out of ideas and this is the best they can come up with, and cos it sounds intricate, complex and unfathomable...then it must be right!...

    We live in a physical universe, it is all explainable, its not complicated in the way a lot seem to imply and its all out ther for us to understand...why complicate soemthing so simply beautiful. Why dont they try and complete the knowledge we have on the one universe we do know exists before they start explaining the mechanics of something that doesnt exist.....
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook