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Featured Understanding Cosmology (Post 4)

Discussion in 'Science and Religion' started by Meow Mix, Jun 24, 2021.

  1. Meow Mix

    Meow Mix Chatte Féministe

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    This is not an example of "invention." This is an example of making a prediction based on theory, then recording actual data from the real world and finding that the data matches the theory (and quite clearly falsifies some other theories).
     
  2. JoshuaTree

    JoshuaTree Flowers are red?

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    Regarding "other universes", do you consider anything falling beyond the particle horizon to be another universe or do you view everything since the big bang as one continuous universe even though ever larger portions are becoming inaccessible to us?
     
  3. Meow Mix

    Meow Mix Chatte Féministe

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    That depends on a few things. I consider stuff beyond our cosmological horizon part of our universe, just not part of our causal universe.

    However in some models, like eternal inflation, there would be a boundary where our universe interacts with inflaton fields; and elsewhere in those inflaton fields would be other “bubble universes.” It’s unique to me compared to multi-dimensional multiverses in that the other “bubbles” would share the same spatial dimensions in many respects but for all intents and purposes be separate universes.

    I think Leonard Susskind called multiverses in which the “pocket universes” shared dimensions some other term, like “megaverse.”
     
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  4. JoshuaTree

    JoshuaTree Flowers are red?

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    Another quick question when you have the time...

    If the speed of gravity is limited by the speed of light how can a singularity form? I understand stuff spirals into a black hole but stuff stops at the event horizon, right? In order to penetrate the event horizon gravity would have to act on the stuff at faster than light speeds below the event horizon? Is there, or can there be, stuff falling into the central point of the singularity after the formation?
     
  5. Meow Mix

    Meow Mix Chatte Féministe

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    I feel compelled to also point out that no multiverse is rigorously defended by consensus, they are just interesting possibilities. More philosophy than science at this time.

    Though there’s more to it than just that (e.g. we can confirm a lot of things about inflation, and inflation carries the consequences of there probably being “bubble universes,” but we can’t directly observe such things, so…)
     
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  6. Native

    Native Free Natural Philosopher & Comparative Mythologist

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    Oh, yes predictions. Let´s see how these works in modern cosmological science:

    First it was predicted that Newtons laws of celestial motion was universal, but it wasn´t after all. Did scientist then revised the law and looked after other observable and explainable fundamental forces which could be at play?

    No. They just INVENTED a cosmic force which theoretically and mathematically could fit to the contradicted law, thus inserting a force mostly in order to patch the failed initial prediction.

    This is IMO not a sane scientific method at all.
     
  7. Meow Mix

    Meow Mix Chatte Féministe

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    Stuff falls through the event horizon without any issue. Mostly any issue. It was once thought stuff would encounter a firewall of Unruh radiation, but that’s since become defunct.

    What you’re probably thinking of is the time dilation of being dropped down to the horizon of a black hole: an observer that survives being lowered would perceive the rest of the universe speeding up and external observers would see the unfortunate lowered observer appear to slow down. But from the person being lowered into the hole’s perspective, time travels at a normal rate and they simply lower into the hole.

    Black holes’ event horizons are proportional to their mass (and the proportionality is interesting, and related to their thermodynamics). Supermassive black holes have such large horizons that if you considered the whole thing, they’d be less dense than water.

    Once inside the event horizon, stuff spirals in to the central clump. Black holes aren’t really “holes,” they are clumps of extremely condensed degenerate matter. So stuff that falls in adds to the extremely dense degenerate matter.
     
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  8. JoshuaTree

    JoshuaTree Flowers are red?

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    Specifically, any mass below the event horizon of a black hole falls outside the known universe because of light speed the same as stuff beyond the particle horizon? So the mass of the star creating the singularity would disappear into a singularity surrounded by a event horizon that collects mass from unfalling objects. If true and if gravity limited by light speed then should detect matter gravitationally disappearing on formation of black hole?
     
  9. Meow Mix

    Meow Mix Chatte Féministe

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    The mass of objects falling into a black hole is added to the black hole’s mass; so the gravitational force exerted by the black hole would increase based on the mass of the consumed thing. (The event horizon also gets bigger).

    The stuff from the star doesn’t disappear; it’s just hidden behind a horizon now. In relativity, the hole’s gravity still affects other things because its mass warps the local geometry of space (this is where you get analogies where a bowling ball is placed on a trampoline, and rolling a marble near it causes it to orbit the bowling ball).
     
  10. JoshuaTree

    JoshuaTree Flowers are red?

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    You say the stuff from the star is "hidden" behind a horizon. This seems analogous to stuff hidden beyond the particle horizon. In the case of stuff beyond the particle horizon finite gravity can no longer contribute, yet in the case of stuff below the event horizon finite gravity does contribute? This seems contradictory to me. Are the two theories in opposition?
     
  11. JoshuaTree

    JoshuaTree Flowers are red?

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    This might seem a weird question but what the hey...

    Do we see CBR on the event horizon of a black hole same as we see on the particle horizon? Or to say in another way is the CBR we see on the particle horizon actually an event horizon dispersed over 14.4 billion light years?
     
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  12. Meow Mix

    Meow Mix Chatte Féministe

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    Gravity can contribute beyond horizons, but by this I have to carefully phrase it: the gravitational field contributes, but gravitational radiation does not.

    You’re asking good enough questions that the simple analogies break down and we have to get to the “yes, but…” parts.

    So, with a black hole, it is surrounded by a gravitational field by virtue of existing; this field is infinite and permeates space. In QFT, gauge bosons aren’t emitted from objects so much as they are excitations of the related fields.

    So gravitons could not be “emitted” from beyond the event horizon; but because the gravitational field extends beyond it, and is informed by the mass of the hole itself, we still end up with gravity related to the hole’s mass.

    This is also true of charged black holes (they have an electronagnetic field — nobody tell @Native — and photons are the gauge bosons for EM force, so the question might arise, “how can a black hole have charge if photons can’t escape the event horizon?”). The answer is the same: photons can’t leave the event horizon, but the EM field can and does, and it can get excitations outside of the event horizon. So you can have a charge while also maintaining that photons don’t escape the horizon.

    This is still a simplification (I mean we’re talking about quantum field theory here), but hopefully gives a good conception.
     
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  13. Meow Mix

    Meow Mix Chatte Féministe

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    We don’t see CMB all the way to the horizon; we can only see CMB to the point of last scattering. I’ll post a graphic that will intuitively show what I mean by this later today. I’m going to sleep now ^.^
     
  14. Native

    Native Free Natural Philosopher & Comparative Mythologist

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    @Meow Mix
    I got this part in my mailbox too. What happened with that?
    Why this comment? Don´t you like to encourage your fellow debaters? :)
     
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  15. JoshuaTree

    JoshuaTree Flowers are red?

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    I don't yet know what "gravitational radiation" is but I will soon find out. :)

    A black hole emitting "gravitational radiation" seems a very close analogy to "cosmic background radiation"... Are they the same thing essentially? If so, maybe what we think is CBR from the big bang is really gravitational radiation from the shear of matter falling beyond the particle horizon, a shockwave of sorts?
     
  16. Heyo

    Heyo Well-Known Member

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    There is one model in cosmology called the "holographic universe" which assumes we are living inside a black hole. And that is technically correct as when you sum up the known mass of the universe and calculate the Schwarzschild radius it comes out slightly bigger than the observable universe.
     
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  17. JoshuaTree

    JoshuaTree Flowers are red?

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    That's interesting in a "Horton hears a Who" sort of way. :)
     
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  18. Meow Mix

    Meow Mix Chatte Féministe

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    I tagged you on purpose, it was a joke ^.^
     
  19. Native

    Native Free Natural Philosopher & Comparative Mythologist

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    I know - but I also know there is no smoke without a fire. Anyway, you confirmed the EM importance around the galactic center which consensus science call a "black hole" - which I simply call a natural "transformative funnel of formation" governed by the EM force.
     
    #79 Native, Jun 30, 2021
    Last edited: Jun 30, 2021
  20. Meow Mix

    Meow Mix Chatte Féministe

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    Gravitational radiation would be gravitons.

    This is different: gravitational radiation would be gravitons. The CMB are photons.

    Black holes can emit photons as Hawking radiation. Cosmic horizons may emit similar radiation called Unruh radiation, but as far as I know Unruh radiation has not been testable so far and is mildly controversial because of this; so there's not a great consensus on whether Unruh radiation exists. But it's possible that it does.
     
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