Big Bang: Escape Velocity Change from >c to <c?

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Discussion Overview

The discussion revolves around the nature of the Big Bang, particularly whether the early universe could be considered a black hole due to its escape velocity exceeding the speed of light. Participants explore the implications of this idea over time as the universe expanded and question the relationship between mass, energy, and gravitational effects in the context of the Big Bang.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants propose that if all mass of the universe was initially contained in a region of 1mm, it could be considered a black hole with an escape velocity greater than c.
  • Others argue that the Big Bang cannot be accurately described as an explosion in a background of space, as it involves the expansion of spacetime itself.
  • A participant calculates the minimum mass required for a 1mm black hole using the Schwarzschild radius, suggesting that a mass of about a tenth of the Earth's mass would suffice.
  • It is noted that immediately after the Big Bang, matter did not exist in a conventional sense, but rather as a plasma, complicating the idea of compressing matter into a small volume.
  • Questions are raised about whether the Large Hadron Collider (LHC) could recreate conditions similar to the Big Bang, with some expressing skepticism about its potential outcomes.
  • One participant reflects on the gravitational equivalence of energy and matter, suggesting that both have similar effects despite being different forms.
  • A later reply questions the transition from discussing expanding spacetime to the concept of "holes in space," seeking clarity on the conditions under which such distinctions are made.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the nature of the Big Bang and its relationship to black holes, with no consensus reached on whether the early universe can be classified as a black hole or the implications of such a classification.

Contextual Notes

Some discussions involve unresolved assumptions about the nature of mass and energy in the early universe, as well as the limitations of current physical laws in describing singularities.

edpell
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If all mass of the universe was in a region 1mm in extent then was it a black hole (escape velocity greater than c)? Now 13 billion years later the universe is bigger. What is the escape velocity now? Did it change from >c to <c?
 
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The big bang is an odd phenomenon. Singularities are a problem for current physics. I don't think you can really think of the big bang having arisen out of a black hole (Current Physical laws don't seem to work at the moment of the big bang or before, only something like 10^-42 seconds afterwards). There is no escape velocity for the universe, as far as I know you can not leave the universe...
 
edpell said:
If all mass of the universe was in a region 1mm in extent then was it a black hole (escape velocity greater than c)? Now 13 billion years later the universe is bigger. What is the escape velocity now? Did it change from >c to <c?

Since the Schwartzchild radius tells the maximum radius a given mass could have to be a black hole, we can calculate the minimum mass of a 1mm black hole.
[tex]R_{Schwarzschild}=\frac{2GM}{c^2}\approx 3km(\frac{M}{M_{sun}})[/tex]

So setting the Schwarzschild radius equal to 1mm, we get 7*10^23 kg, about a tenth the mass of the Earth.

Really, the smaller a black hole you can achieve (good luck overcoming degeneracy pressure), the less mass you need. (A massive body becomes a black hole depending on the density.)

However, there's a much more important issue here. The Schwartzchild radius describes black holes in space. The big bang was not an explosion in a background of space. The big bang involves spacetime itself expanding from a single point. The universe (which may or may not be infinite) has always had a nearly homogenous and isotropic mass distribution.

In addition, it might interest you that the big bang had excruciatingly low entropy while black holes have the highest possible amount of entropy in a given region of space.
 
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edpell said:
If all mass of the universe was in a region 1mm in extent then was it a black hole (escape velocity greater than c)?

Fact is that just after the BigBang, matter did not exist. There was something like a soup of plasma more or less seethrough. It took "very long" for matter to form.

Therefore, you cannot think in the sense of compressing matter into a very small volume. You need to see the Big Bang as a release of energy that eventually formed elementary particles, that eventually formed nuclei, that eventually formed atoms, that eventually contracted to form the matter as we know nowadays.

Cheers
 
Does your collective thinking believe that the LHC can create a Little, Big Bang?

If yes, then that is a lot of bucks for the bang! ... or will it answer the $4.5B question! Is the Higgs Boson the end of the question? What is the next question?

OR, if the answer is no, then 1.) another failed attempt? , or 2.) WHAT? "We came, we saw, we conquered, we left suddenly!"
 
Bethann said:
Does your collective thinking believe that the LHC can create a Little, Big Bang?

By just taking a quick look at the CERN's website makes you realize that they are not focusing on just one particular field. The CERN is a research center open to all research team around the world.

Some of their projects, like the ATLAs has a very specific focuse, and they will use part of the beam. But other research are always welcome to apply for beam time.

Cheers
 
Bethann, I enjoy your sense of humor "we left suddenly" :)

Fatra2, I do not think it "matters" (sorry for the pun) if the stuff is energy or matter I get the impression these are about the same as far as gravitational effects are concerned.

Jolb, your remarks about a "hole in space" versus "spacetime itself expanding" contains so many ideas I do not know where to being and many of the ideas I do not understand. I would ask when can we talk about holes in space? How big does the universe need to be? If a 1mm black hole is about a tenth the mass of the Earth then using 10^55kg as the mass of the universe we can make 1.6x10^30 black holes. If they are all packed next to each other than there was a time when the universe was about 11,000km in radius it "contained" 1.6x10^30 black holes packed cheek to jowl. How do you think about this? At what point do we move from expaning spacetime to hole in space?
 

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