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Perhaps we live in a black hole?

  1. Dec 31, 2009 #1
    Pondering the mysteries of the universe, I thought about how the big bang seemingly came from nothing, and how black holes seemingly send stuff to oblivion. Maybe these two go together I thought? I found out that an astrophysicist named Lee Smolin thought the same thing. I just read his book, "Life Of The Cosmos", and I'm pretty enamored w/ his ideas. Some of the things I was thinking about though that he didn't touch much on were that according to this idea, we are essentially living in a black hole of a parent universe. The stuff falling into our black hole is what is causing what we call dark energy. This idea is similar to brane theory, but somewhat different. I think a way to test this would be to measure whether dark energy is constant. If we are in a black hole and stuff is falling into our universe, one would think that the power of dark energy would fluctuate over time. It might even nearly stop if our black hole finishes gobbling up all the matter and light in its region of our parent universe. Unfortunately, these perturbations may only be noticeable over millions or billions of years as we can see that some quasars take vast amounts of time to gobble up galaxies. On the other hand, if we do find dark energy to fluctuate, it'd positively reinforce my idea. (and not merely constantly accelerate forever) My other question is though, what happens when our black hole collides w/ another black hole in our parent universe? I would imagine a universe-wide big bang. Although that makes it seem like our universe has probably had several big bangs as our universe has combined w/ several other black holes from our parent universe. Perhaps what we think of as the big bang occurred when our universe was already quite large. It seems like an ugly extrapolation to assume that everything necessarily went back to a singularity, but this idea isn't central to my above hypothesis. I would guess that such collisions would probably wipe out all life across our universe instantaneously and w/o warning :(

    Is this making any sense?...thoughts?
  2. jcsd
  3. Jan 1, 2010 #2
    The mathematics of a closed universe are identical to those of a black hole. So if we are in a closed universe, it could be a black hole that got pinched off from a parent universe. One thing that makes the math interesting is that things that are falling into the black hole in space, end up falling into the black hole in time.

    The hard part in all of this is to work out all of the math (i.e. if we were in a black hole) what would the universe look like?

    One weird idea that has been suggested is that whenever a black hole forms, there is a big bounce at the singularity which causes a new universe to get created in a different dimension. The reason this is interesting is that it's been suggested that only universes that can form stars can form black holes so that there is a evolution toward universes that can have stars.

    Coming up with crazy ideas is not that hard. The hard part is now that we have this crazy idea, what's the observational test we can do to refute the idea.
  4. Jan 1, 2010 #3
    Well, if we can make predictions that turn out to be true, then we are on our way towards forming a better understanding...and as smolin has pointed out, if indeed we live in a multiverse where black holes make more universes, it is probable that we live in a universe that is fairly fine tuned to make black holes...according to him, if you increase/decrease 8 of the ~20 variables that make the universe exist, you would end up w/ fewer black holes...so if we can somehow simulate, or use math to simulate a universe where these constants (mass of electron, planck's constant...etc) are changed slightly, and each of those simulations results in fewer black holes...i would say that is a correct prediction. Why we're here is just as a result of stars...which are needed to make black holes...
  5. Jan 1, 2010 #4
    If we can make predictions that turn out to be false, then we are also on our way towards forming a better understanding of the universe. False predictions turns out to be more useful than true predictions, because with true predictions, you don't know if you just "got lucky" and the universe just happens to fit what you predicted even though you are totally wrong about why. With false predictions, you can say to yourself "well that doesn't work."

    But getting any sort of prediction at all is really, really hard.

    And if you vary the constants and you find out that whatever you do, you end up with black holes, that pretty much kills Smolin's idea, although you might be able to salvage something, and "Smolin is wrong" is progress.

    The problem with this line of thinking, is that it's not obvious how changing planck's constant would change star formation. It's pretty clear that if planck's constant were different, stars as we know them wouldn't exist, but it's not clear whether you'd have some other mechanism of black hole formation. The other problem is that it's not clear what gets changed and what doesn't, and how to change the constants.

    One of the points of theory is not to answer questions but to ask them. You know that you have a good idea when you think about a question and you come up with a dozen new questions. What would the universe look like if Planck's constant changes? Is creating stars the only way of creating black holes? How does the fact that black holes evaporate change things? OK you are in a black hole, it's evaporating because of Hawking radiation? What happens to you?
  6. Jan 1, 2010 #5


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    Twofish, have you read Smolin's papers about this? Changing planck's constant is not what its about. Planck's constant is dimensionful. It is not one of the 20-some dimensionless numbers that plug into the standard model.

    Let's say roughly 30 numbers, counting those that plug into the standard cosmology model.
    It is those 30 numbers that are involved in the hypothesis. Newton's G, the speed of light, and Planck's constant are not involved.

    A fair amount of research by various people, Smolin and others, has gone into trying to understand how things like galaxy formation, star formation, and exhausted star collapse are influenced by varying dimensionless standard model parameters. It's not entirely satisfactory, but one can say certain things.

    Before dismissing the hypothesis, you might want to check the reasoning that underlies some of the predictions.
  7. Jan 1, 2010 #6
    I fully agree; there is no danger of a false positive...to find the answer you'll inevitably need to make reliable true predictions tho of course

    Thats a good point...hadn't thought of that

    True, but we could just arbitrarily change them all around in every way and see wut happens...anybody got a dyson sphere laying around for all these simulations?

    He says varying 8 of the ~20 constants lowers black hole formation...the other 12 are harder to figure out wut happens...i really don't know tho, i'm just a layperson :)

    Ooh, thats a good one...maybe it counteracts dark energy...better yet, maybe the hawking radiation of our black hole is wut we see as gravity, both are really weak in comparison to other forces...

    I brought up those variables specifically, not twofish...i'm not entirely sure which ones were involved, though I thought newton's G and the speed of light were among those involved, though I could be wrong...

    I just like throwing this stuff around in my head...there's gotta be some sort of explanation, we may or may not figure it out...but to throw one's hands up in the air and say 'i can't know'...that sucks...reminds me of Neil Tyson's talk about how various scientists through history (particularly newton) would eventually get to a point and be like 'I can't know anymore, thats only for god to know'...which would result in a total stoppage of further understanding...it makes me just want to attack and brainstorm any mysteries that are left...hence this thread...

    Thanks for the Replies! :)
    Last edited: Jan 1, 2010
  8. Jan 1, 2010 #7


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    Random thought: A black hole implies a preferred point or points (the singularity). Since this goes against the Copernican principle, we cannot be living in a black hole if the Copernican principle is true. Does this make sense?
  9. Jan 1, 2010 #8
    There are plenty of black holes, ours would be nothing special...i don't think it would violate the copernican principle...rather cosmological natural selection explains our universe in an ecosystem of universes similar to humans not being central to life on earth, but rather just another mammal
  10. Jan 1, 2010 #9


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    Well sure there are plenty of black holes, but we only believe that the Copernican principle is true only on >Mpc scales or so. No black holes are of that size. However, if our universe was a black hole, that is obviously above Mpc's.
  11. Jan 2, 2010 #10
    I see what yer sayin now...I suppose we could be in good standing w/ the copernican principle if we could see our parent universe and find that it isn't much different from our own...and if we could see into our child universes and find them to also not be much different from our own...and likewise for each observation of each generation thereof...thats wut cosmological natural selection predicts...

    sure our local neighborhood of stars is heterogeneous compared to distant galaxies, but its thought that this is because the more distant ones are further back in time and that the local stuff looks different because its older. I think this idea and the homogeneity of the CMB confirm the copernican principle on not just >Mpc scales but in our universe generally.

    Just because CNS (cosmological natural selection) says our universe is coming from a black hole (a point) doesnt mean its a preferred point....the preference or centrality is wut goes against he copernican principle
  12. Jan 3, 2010 #11
    I tend to be rather skeptical about statements regarding how star formation and stellar collapse happens under an alternative universe since we really don't know how it happens under the current set of conditions. The other issue is that it's not clear to me how you can exclude "star like things" that have no analogy under the current set of predictions.

    The problem with star formation and collapse is that they tend to be extremely tightly coupled non-linear processes in which the connection between model inputs and model outputs is not well understood. You can try to do things with rough calculations, but those are pretty weak arguments.
    Last edited: Jan 3, 2010
  13. Jan 3, 2010 #12
    Not directly since those are all non-dimensionless numbers, but G, speed of light, and planck's constant are derived from things like the fine structure constant. If you change Planck's constant, it doesn't directly change the model, but it will change all of the inputs.
  14. Jan 3, 2010 #13
    Also someone sent me a message in which they pointed out something really important, which is that if you want to argue that we are living inside a black hole, you have to argue that "something weird" happens that causes the black hole to bounce when it becomes a singularity. Before the bounce, the black hole is collapsing whereas we live in a universe that is expanding.
  15. Jan 8, 2010 #14


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    Why would universal processes be different in an alternative universe? Yes, I know there is such idea, but whats behind it? Just because noone can tell for sure? IMO if every black hole is another universe, then it is as simple as matter falling into it, going from one universe to the other, and I don't see a reason for matter interaction to be something fundamentally different in another hypothetical universe.
  16. Jan 12, 2010 #15
    Some time ago I make this calculation:
    - http://en.wikipedia.org/wiki/Observable_universe#Mass_of_the_observable_universe" is Mou = 6*1053 Kg (including DM and DE)
    - gravitational constant is G = 6.67428*10-11 m3Kg-1s-2
    - speed of light in vacumm is c = 299792458 ms-1

    Diameter of a black hole that contain all Mou mass is the double of Schwarzschild radius:
    DBHou = 2*Mou*G/c2

    If we put all this in the search field of Google like here, we have:
    DBHou = 9.41952208 × 1010 light years or 94,2 billiards light years.

    The diameter of observable Universe is almost 93 billiards light years.

    Is this just a coincidence? Or can be considered this as a prove of the fact that we can be in a BH?
    In fact, GR are saying that we are in a space zone with a volume that contain enough matter to form a BH, doesn't it?
    Last edited by a moderator: Apr 24, 2017
  17. Feb 7, 2010 #16
    I thik our universe has a ciclycal way of existing.
    -the big bang theory says that a point whith no dimensions (that i will call *) expanded and formed the univesre.
    -the big crunch theory says that the universe will stop expanding,than it will slowly get back in *.
    -if this will happen we will have another *-that is practicly the same *.
    -but the universe is going to implode slowly by itself,or it is going to implode because of a blackhole (or at least helpded by a black hole)?
    -and if it is going to implode,why it should explode?
    -and if it has a ciclycal way of existing,where does it come from?-waaaaait there is a certain entity that makes us ask ourselfs the same question-that entity is god.
    (god was not created,he only exists)
  18. Feb 7, 2010 #17
    There is another thing that cannot be created,neither destructed,but it can be transformed-that thing is energy.and if e=mcc and mass is 0 and time is 299792458 we will have that the time between * imploded and its explosion was 0 seconds and the energy needed to make it explode was 0.
  19. Feb 10, 2010 #18
    Let me try that math on my calculator 12x10^53*6x10^-11/10^17 = 72x10^25meters
    1 light year is about 10^16meters so we have 72 billion light years. It is an interesting number. Very Arthur Eddington.
    Last edited by a moderator: Apr 24, 2017
  20. Feb 20, 2010 #19
    Well if there is a "parent" universe, how did that one get created? We can't quite tell how ours did. Heck, we could even be part of a bigger organism, in fact, we could even be as tiny as the germs we study today.
  21. Feb 20, 2010 #20
    The world is flat and sits on the back of a turtle. Smart *** question what does the turtle stand on. Smart *** reply it's turles the whole way down.

    So it is clear black holes the whole way up and down.
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