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Thread: Age of the Universe

  1. #1 Age of the Universe 
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    For a black hole of a mass equal to the mass of the Sun, the entire process for it to disappear would take about 10**66 years, or 1 with 66 zeros after it.

    Thats 1,000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000,000, 000, 000, 000, 000, 000, 000, 000, 000 years

    and thats a very small (in fact tiny) black hole.Only 3km across, on this scale the earth would be 9mm ac
    ross (the size of a peanut)

    The black hole in the center of our milky way galaxy is 4.1 million solar masses (and even it is a baby)

    The ones that we have detected from our very limited vantage point on earth can get up to 100-billion-solar-mass, thats a lifespan of 2.099496 followed by 100 zeros, it would have a radius of 1975.198 AU (1 AU is the distance between earth and the sun) or 1.836061 followed by 11 zeros km

    So whats my point, If we lived in a universe of just black holes, and one really large one went "supernova" in a big bang type event, would we see the evidence that we see today. Dark energy, faster than light acceleration in early universe, dark galaxies (just a galaxy of black holes) that existed before the big bang lighting up with the remains of the explosion (an injection of fuel and basic building blocks from the explosion etc)

    and the ultimate question with these sorts of life spans. Is the universe much older than we think it is?



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    Quote Originally Posted by Always.Asking View Post
    So whats my point, If we lived in a universe of just black holes, and one really large one went "supernova" in a big bang type event, would we see the evidence that we see today.
    There is no known mechanism for a black hole to go "supernova". And an explosion somewhere in space would look totally unlike the expanding universe we observe (which is why it is modelled as expanding space, rather than an explosion).

    faster than light acceleration in early universe
    Acceleration is not a velocity and so cannot be "faster than light". Expansion is not a speed, so it too cannot be "faster than light". On the other hand there are, and always have been, points in space that are separating faster than the speed of light (they just need to be sufficiently far apart, as recession speed is proportional to distance).

    dark galaxies (just a galaxy of black holes)
    I can't imagine how such a thing could occur. Only a small proportion of stars become black holes.

    that existed before the big bang
    There is no evidence of what existed before the big bang (or even that "before" has any meaning).

    Is the universe much older than we think it is?
    There is no evidence for that. Which is why the universe is thought to be the age it is.


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    Why is it that everyone seems obcessed with black hole's blowing up. The nature of the physics of a "Black hole" is that it can't blow up. What goes in, stay's in. A black hole is not a container that can be over filled. It is a container that is generated by the amt of filling it has. The more you put in the stronger the "walls" become.
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    Most models of the universe I'm aware of that haven't been discredited, with few exceptions, have the laws of physics break down pre-Big Bang. What 'caused' the Big Bang might be irrelevant. It could very well be that causality itself ceases to exist. This is probably why even Stephen Hawking, who states that there is no need for a G-d or universal consciousness, admits that the most reasonable place to fit G-d in to creation would be pre-Big Bang as the catalyst for the first event. So, uhh, I guess my point is that speculating on the actual pre-Big Bang origins of the universe is really, really hard. Even for the highest end astrophysicists. So I'm hardly qualified to really answer your question, but after reading it am still fairly confident saying 'probably not.'
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    Quote Originally Posted by SowZ37 View Post
    Most models of the universe I'm aware of that haven't been discredited, with few exceptions, have the laws of physics break down pre-Big Bang. What 'caused' the Big Bang might be irrelevant. It could very well be that causality itself ceases to exist. This is probably why even Stephen Hawking, who states that there is no need for a G-d or universal consciousness, admits that the most reasonable place to fit G-d in to creation would be pre-Big Bang as the catalyst for the first event.
    Altho' I am an atheist I do agree "that the most reasonable place to fit G-d into creation would be pre- Big Bang as the catalyst for the first event" or first cause of the Universe.
    Of course, this point of view long preceded Hawking!
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    Hi everyone and thanks for the responses,

    This was not meant to be a conversation on God or god or "there is no evidence" debates.

    I understand there is no evidence for these sorts of topics, I wanted to discuss hypothetical ideas, postulating forward

    A couple hundred years ago there was no evidence a star could go supernova, why cant a black hole.

    "Acceleration is not a velocity and so cannot be "faster than light". Expansion is not a speed, so it too cannot be "faster than light". On the other hand there are, and always have been, points in space that are separating faster than the speed of light (they just need to be sufficiently far apart, as recession speed is proportional to distance)."

    What I was referring to here, is inside the event horizon of a black hole, between the "centre" and the event horizon. Yes, I know about space expanding and I have a basic understanding of relativity, but its a huge hole in our physics, that's why I wanted to discuss hypothetical scenarios

    We have absolutely no idea why a black hole would go "supernova" but 100+ years ago, we knew of no mechanism that would keep the earth warm as it has or keep the sun burning for as long as it has.

    "I can't imagine how such a thing could occur. Only a small proportion of stars become black holes."

    That's an interesting view but I feel its flawed, the time scales you are looking at it from are to small. Yes lets say only 1 in 1000 stars go black hole, and the rest go supernova. So we end up with 2nd generation stars, 3rd gen stars etc and on a long enough time scale, all "fuel" in a galaxy is exhausted. What would you call the structure that remains.

    "There is no evidence of what existed before the big bang (or even that "before" has any meaning)."

    Yeah I agree there completely there is no evidence, which I feel could change once we start detecting gravity waves. But then again, how much evidence do black holes really leave? Nothing or?

    "There is no evidence for that. Which is why the universe is thought to be the age it is."

    Yes I understand why and how we determine the age of the universe, I was just hoping for a discussion on some of the questions that I have asked. There is no evidence for most of what I'm talking about here, but if the evidence was out there I would just go read books, instead of trying to get a conversation going.

    We are scientists, throughout history we have looked behind the curtain and surmised and guessed then we go looking for the evidence, I was just hoping for some open discussion without ridicule, or a string of "there is no evidence" comments, no disrespect

    Thanks for the discussion, I appreciate all the feedback thus far


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    Quote Originally Posted by Always.Asking View Post
    A couple hundred years ago there was no evidence a star could go supernova, why cant a black hole.
    Black holes are very well characterised by our current best theory of the universe. This may/will change if and when we have a theory of quantum gravity. This might lead to the possibility of black holes exploding, but there isn't much indication of that currently. The most extreme notion is that they might radiate energy away slightly faster than we currently think.

    What I was referring to here, is inside the event horizon of a black hole, between the "centre" and the event horizon.
    OK, but you said "faster than light acceleration in early universe", which is what I was responding to. Something falling into a black hole reaches light speed at the horizon (in as much as you can define speed there) and continues to get faster.

    Yes, I know about space expanding and I have a basic understanding of relativity, but its a huge hole in our physics, that's why I wanted to discuss hypothetical scenarios
    What is a huge hole in our physics?

    We have absolutely no idea why a black hole would go "supernova" but 100+ years ago, we knew of no mechanism that would keep the earth warm as it has or keep the sun burning for as long as it has.
    This isn't meant to sound mean, but I don't see much point to just saying "let's ignore the evidence and theory" - outside of science fiction.

    That's an interesting view but I feel its flawed, the time scales you are looking at it from are to small. Yes lets say only 1 in 1000 stars go black hole, and the rest go supernova. So we end up with 2nd generation stars, 3rd gen stars etc and on a long enough time scale, all "fuel" in a galaxy is exhausted. What would you call the structure that remains.
    The majority of old stars would be left as white dwarfs, neutron stars and similar remnants (with their planets). Most of the matter in the universe would still be hydrogen which is not dense enough to collapse and form stars.

    But then again, how much evidence do black holes really leave? Nothing or?
    There are quite a number of observations which are not just consistent with the presence of black holes, but can only be explained by black holes. Things like pulsars, quasars, relativistic jets, orbits of stars, etc.

    We are scientists, throughout history we have looked behind the curtain and surmised and guessed then we go looking for the evidence, I was just hoping for some open discussion without ridicule, or a string of "there is no evidence" comments, no disrespect
    But that really isn't how science works. There might be very rare discoveries by chance or a "lucky guess". But most of the time research is done by following existing evidence or working from existing theories. The hope is always to find some evidence that existing theories are wrong, in some way, so that new physics can be discovered.

    I hope you don't feel I am being too negative (I think of it as realistic ) or ridiculing your ideas. Personally, I just don't see any value in discussing ideas for which there is no evidence and no theoretical basis. But that is just me. There will no doubt be others who think me unimaginative and closed minded. Hopefully, they will engage in your discussion!
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    I think a more fruitful discussion would be "do black holes exist". But then again most cosmology is a mixture of fundamental assumptions upon which are built theories based on observations ans science.
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    Quote Originally Posted by ad31vg10 View Post
    Secondo i rapporti, la Cina nel 2012 si prevede di superare il Giappone a diventare il più grande lusso del commercio
    Per favore, non mi rompere i coglioni.

    Diecimila grazie.
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    Something falling into a black hole reaches light speed at the horizon (in as much as you can define speed there) and continues to get faster.
    Strange, can you expand on this please?

    My understanding is that an object would only cross the horizon at lightspeed if it had fallen from an infinite distance. and the getting faster bit eludes me too. surely relativity still operates within the BH until quantum effects take over?
    Sometimes it is better not knowing than having an answer that may be wrong.
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    Quote Originally Posted by Chrispen Evan View Post
    Something falling into a black hole reaches light speed at the horizon (in as much as you can define speed there) and continues to get faster.
    Strange, can you expand on this please?

    My understanding is that an object would only cross the horizon at lightspeed if it had fallen from an infinite distance. and the getting faster bit eludes me too. surely relativity still operates within the BH until quantum effects take over?
    The Laws of Physics in general likely break down at the center of a BH. Not in all models, but still.
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    ~ I noted a question of ''Do black holes exist ?" and feel I can answer this as I have some knowledge of Radio Telescope mapping of the most distant radio sources.. We have a good and solid understanding of emissions of x-ray and radio waves from seemingly invisible objects. We can deduce that some near to it visible light object must be orbiting a unseen object of considerable mass..
    ~ We are aware of a 'Black Hole' and by the motion of objects near it. Calculate a mass figure.. As hard as it can be to just agree.
    Until information changes our view the Black Hole exists. I have limited my post to this part of the thread because the rest of it is as the best guess view gives us.. and I have no argument with it..
    ~ I will table a suggestion that has little support and no obvious fact to base it on. In falling mater that has failed to orbit and being added to the mass of the BH does not seem to emit anything after it crosses the gravity wells horizon ( event horizon) which is in part why we think inside that sphere c. is exceeded. We can not know this by a method other than a high probability factor.. The rules of existence of mater may not apply. My outrageous addition to this is that 'It may just electorate to a singularity where it's mass becomes pure energy.' I will not argue of what I do not know. The answer will come from a mathematician of astrophysics. ~ maybe.
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    AlwaysAsking,

    I was wondering pretty much the same thing, whether black holes could provoke inflation in the center. The inflation would be faster than light so the matter/ energy it countains would get out of the BH ( the horizon would shrink rather). That would happen in the far future when the universe has expanded enormously.

    This sounds a bit like Lee Smolin's idea of evolution of universes via stellar black holes. Smolin also spéculâtes about the possibility that a sort of inflation could happen Inside the BH.

    I also listened to an interview of Brian Greene not long ago where he was speculating about the possibility of creating a universe by provoking an inflation. He was suggesting creating a mini black hole weighing about 10lbs, and doing something to it ( he wasn't sure how to do it exactly). He wasn't sure if he could work, but in any case he was wondering about that.

    If the result of the BICEP experiment turns out to be true and our universe has really started with an inflation, the next question is what caused this inflation. Are we in an inflationary universe or is there another process.

    And regarding the theory of eternal inflation, I read this article yesterday by Sean Caroll. According to him, is not that sure that an eternal universe is that likely:
    Squelching Boltzmann Brains (And Maybe Eternal Inflation) | Sean Carroll
    The stakes are substantial: the fact that inflation is eternal is a key part of its motivation in the minds of many cosmologists. (Note that we’re not saying eternal inflation is impossible; if you are stuck in a false vacuum with a very tiny decay rate, you can stay there for an arbitrarily long time. But the set of models in which inflation is eternal might be much tinier than was previously believed.)
    All this is very speculative and the idea that a BH could provoke an inflation is far-fetched, but anything is far fetched anyways when it comes to the origin of the universe.
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    Black holes are very well characterised by our current best theory of the universe. This may/will change if and when we have a theory of quantum gravity. This might lead to the possibility of black holes exploding, but there isn't much indication of that currently. The most extreme notion is that they might radiate energy away slightly faster than we currently think.
    I am not a scientist but from what I heard there seems to be quite a controversy about black holes since the issue of firewall has come up. I even heard Leonard Susskind say that he was surprised that no one thought about the problem before because it was relatively obvious.

    There is also the Hawking's paper where he says that BHs don't exist ( "in the sense that light can't escape" ). Now he wants to replace the event horizon with an apparent horizon.

    Our current models might be sufficient to model a BH from far outside of it, but we still don't know for sure what happens at the horizon, and at the center.

    Finally, if our universe has started with an inflation, scientists have to deal with the question of what could start an inflation. Shouldn't we at least wonder about the BH possibility?
    Last edited by Nic321; May 23rd, 2014 at 07:49 AM.
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    Quote Originally Posted by Chrispen Evan View Post
    Something falling into a black hole reaches light speed at the horizon (in as much as you can define speed there) and continues to get faster.
    Strange, can you expand on this please?

    My understanding is that an object would only cross the horizon at lightspeed if it had fallen from an infinite distance. and the getting faster bit eludes me too. surely relativity still operates within the BH until quantum effects take over?
    It is a bit clearer in Painleve-Gullstrand coordinates, than the usual Schwarzschild description: Waterfall

    Interestingly, this topic came up on another forum recently and someone came up with a fairly intuitive explanation; I'll see if I can find it again.

    Edit. Maybe this will help:
    http://cosmoquest.org/forum/showthre...09#post2211709
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    Quote Originally Posted by Nic321 View Post
    I was wondering pretty much the same thing, whether black holes could provoke inflation in the center. The inflation would be faster than light so the matter/ energy it countains would get out of the BH
    There are no paths out of a black hole, however fast you go.
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    Quote Originally Posted by Strange View Post
    Quote Originally Posted by Nic321 View Post
    I was wondering pretty much the same thing, whether black holes could provoke inflation in the center. The inflation would be faster than light so the matter/ energy it countains would get out of the BH
    There are no paths out of a black hole, however fast you go.
    Space expands faster than light in that case. A photon initially inside the horizon would be pushed outside the horizon by the expansion of space. Even if the photon tries to continue to "fall" in toward the center, its speed cannot compensate for the rate of the expansion.

    Similar thing happens to a photon very far away beyond the cosmological horizon. It tries to go toward us at full speed, but there's no way it can reach us because of the rate of expansion of space itself.


    Anyways I am speculating, I am not sure. I think Smolin sees more the inflation and the new universe staying inside the original horizon.

    Edit: If I understand right, indeed the in-falling matter and photons will reach the center very fast in the scenario of a collapse, like a few seconds/minutes of proper time for a stellar collapse. So if such an inflation happens at the center, wouldn't it stand to reason all the stellar BH that have already formed would already have provoked inflations in our universe. I am not quite sure about all this...
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    Quote Originally Posted by Always.Asking View Post
    For a black hole of a mass equal to the mass of the Sun, the entire process for it to disappear would take about 10**66 years, or 1 with 66 zeros after it.

    Thats 1,000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000,000, 000, 000, 000, 000, 000, 000, 000, 000 years

    and thats a very small (in fact tiny) black hole.Only 3km across, on this scale the earth would be 9mm ac
    ross (the size of a peanut)

    The black hole in the center of our milky way galaxy is 4.1 million solar masses (and even it is a baby)

    The ones that we have detected from our very limited vantage point on earth can get up to 100-billion-solar-mass, thats a lifespan of 2.099496 followed by 100 zeros, it would have a radius of 1975.198 AU (1 AU is the distance between earth and the sun) or 1.836061 followed by 11 zeros km

    So whats my point, If we lived in a universe of just black holes, and one really large one went "supernova" in a big bang type event, would we see the evidence that we see today. Dark energy, faster than light acceleration in early universe, dark galaxies (just a galaxy of black holes) that existed before the big bang lighting up with the remains of the explosion (an injection of fuel and basic building blocks from the explosion etc)

    and the ultimate question with these sorts of life spans. Is the universe much older than we think it is?

    How are you coming up with these figures about the life span of a black hole? I have to think you are assuming that Hawking radiation is a reality. As far as I know it's just a theory that has not been proven yet. Next, where did you come up with a BH that was a 100 billion solar mass size. The largest I've ever found documented is between 20 to 30 billion solar masses.

    Next I would want to know where super massive BH's come from. Every galaxy seems to have one. To my knowledge no one has ever documented an actual BH merger and they've been looking for a long time. That tells me they are not all that common. I'm sure they do happen, but if they are not common how do BH's grow as big as some of them are at this time. I haven't heard of any scientists that believe Billion + solar mass BH's can be formed in just a few billion years, and yet we've discovered Billion + solar mass BH's that were in existence within 2 to 3 billion years of the big bang.

    I have my own theories about that, but I would like to hear some other credible theories that might explain this bit of observed information.
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    As far as blackhole universe models, is it not the case that these generally include a black hole in an otherwise empty space? Where is the theoretical support for a universe full black holes?
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    Quote Originally Posted by JoeSixPack View Post
    As far as blackhole universe models, is it not the case that these generally include a black hole in an otherwise empty space? Where is the theoretical support for a universe full black holes?
    Start with the wikipedia entry on black holes. To go further, look up some of the references cited.

    You'll need to study GR, first, though, if you want to understand what's being discussed, so you have your work cut out for you.

    I recommend reading Oppenheimer and Volkoff's paper of 1938 or 1939. That pioneering work is often considered to have kicked off the field (although, of course, others -- Schwarzschild among them -- had earlier paved the way).
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    Quote Originally Posted by JoeSixPack View Post
    As far as blackhole universe models, is it not the case that these generally include a black hole in an otherwise empty space? Where is the theoretical support for a universe full black holes?
    It is a fairly accepted consensus that any star of sufficient mass will leave a stellar size black hole when it dies in a supernova. However it seems there is a different opinion about what size the star will have to be to make a black hole on it's death. I don't really see this as a problem. When the galaxies were first forming and stars first started coming into existence, many first generation stars were big enough, as it took lots of short lived heavy stars going supernova or hypernova to seed the galaxy with the heavy elements necessary for star systems to be able to support life. I believe our sun is a third generation star formed from gas and dust with the heavy elements needed for our existence. Any stars that formed during 1st & 2nd generation stages of star formation will not contain the elements needed for life as we know it, and that's most of the stars in the Milky Way. So when you hear wild speculation on how many stars there are that can possible support life in our galaxy and others it's usually way out of proportion to the reality of the situation.

    This may not tell how many black holes there are, but I believe there is enough data to give us a good ball park number of black holes. When I have enough time I will find and post what I consider the best article on the subject.

    In the mean time black holes are a fact of nature, and I get really tired of the way black holes are described or characterized in the media. It's true we don't really know what happens to the matter when it has compressed beneath an event horizon, but space on this side of an event horizon is no different than space around any other body of mass in the universe. Black holes have matter that orbits it just like most stars and planets have and they move through space the same as stars do. Once any black hole has been created it will out live all the stars that will ever exist in our universe.

    There will be a time in the far future with no shinning stars, so the universe will become dark, but all the mass that exist now will still exist in the dark universe and it will still be interacting about as much as it does now. The black holes will still be able to grow and merge if the get close enough. This future dark universe will exist hundreds or thousands of times longer than our lit up universe will.

    Has anybody thought about what will happen to all those black holes in the dark universe? I have, but I've not seen any papers or articles on that subject. I find it hard to believe I'm the only one that has thought about it in more detail than the universe will just keep expanding into nothingness.
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    thanks strange. think i got it. the bit about the photon on the EH i can see the logic behind that. i don't have the maths to understand the different metrics.
    Sometimes it is better not knowing than having an answer that may be wrong.
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