TED Conversations

Kurt Arnold

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In the early universe, when matter was much more densely contained why was it that super massive black holes didn't form immediately?

When the universe was very young, the density of matter and energy was very high, in many ways higher than what one might expect to find in a supernova. So why didn't a black hole or multiple black holes form in the early universe and simply gobble the universe up as it expanded?

  • Jun 26 2012: I'm not an expert in the field, but this is what I know of regarding the topic.
    Inflationism is the current idea of how the universe first originated. It states that at the moment right before the universe came to be, everything that is in the universe as we know it was packed into a point, an infintesimally small point, so small that it is as if it doesn't exist. Then the moment of the universe's creation, the universe inflated at exponentially astronomical speeds. I don't know the exact number, but it is very well above the speed of light, with several orders of magnitude. At this point, the universe was only comprised of a bunch of energy, at extreme temperatures and no matter has been created yet. This inflation occurred until the inflation slowed down enough for the enormous amount of heat to dissipate to allow for the electroweak and I think strong(again I'm no expert on the topic) forces to occur. Again, there is no real mass at this time, just a bunch of forces starting to interact with another with the energy available. By the time the temperature cooled off enough for the energy and forces that are there to start producing matter, the amount of space that the matter started taking up was nowhere near small enough for black holes to occur. Once matter started forming(mostly subatomic quarks), they combined together to make the atom(mainly hydrogen) which clumped together at high density areas(due to gravity) which eventually led to the creation of stars, galaxies, planets, and the universe as we know it. An elegantly beautiful theory on the creation of an even more beautiful and elegant universe, yes?
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    Jun 26 2012: excellent question. surely, if the initial mass was within a small area, that is well within the swarzschield radius, so how things escaped the event horizon?

    i don't know, but can think of two possibilities. either because the space itself expanded very fast in early times, and thus matter was able break out this initial event horizon (usual models of black holes assume non-expanding spacetime). or mass formed only later and gradually, so there was never a point in time when black whole conditions were met. which is kinda weird, considering that the observable universe has a swarzschield radius of 10 billion light years, while its radius is 45 billion light year, so only 4.5 times bigger.
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    Jun 28 2012: To be honest no one really knows, but krisztian touches on the two most obvious ways of avoiding a black hole.
    1) when the expansion started there was no matter so gravity didn't work like it does at lower temperatures.
    2) The inflationary expansion exceded the speed of light. (relativity says you can't travel through space faster than "c" it doesn't say anything about how fast space-time can expand)
    At this early stage the whole universe was dominated by quantum effects. We still havn't integrated gravity into quantum mechanics yet. That's the great hope for string theory.
  • Jun 27 2012: Thanks all for your comments and information. Interestingly - I watched a TED presentation last night that touched on this very subject. What the presenter said was - that experts currently believe that matter was extremely uniformly spread in the early universe. That and because the young universe is (currently) theorized to have incredibly low entropy - a black hole could not form. Interestingly - the presenter said - if there was even one small imperfection in the distribution of matter and energy in the young universe - then yes, immediately a black hole would have formed and swallowed the universe just as it was expanding outward.