Big Bang Radiation: Does Gravity Reverse Its Spread?

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Discussion Overview

The discussion revolves around the implications of the Big Bang theory, particularly focusing on the nature of cosmic expansion and the potential future scenarios of the universe, including concepts like the Big Crunch and Big Rip. Participants explore various hypotheses regarding gravitational effects on radiation and matter, the role of dark energy, and the interpretation of observational evidence.

Discussion Character

  • Debate/contested
  • Exploratory
  • Technical explanation

Main Points Raised

  • Some participants question whether the radiation emitted after the Big Bang could eventually be attracted back due to gravity.
  • There is a suggestion that a future "Big Crunch" could occur, potentially leading to another Big Bang, though this is debated.
  • Some participants argue that current cosmological interpretations suggest the universe's expansion is accelerating, making a Big Crunch unlikely.
  • Speculation exists about the possibility of a "Big Rip" if the acceleration of expansion continues to increase.
  • Concerns are raised about the reliability of evidence supporting the existence of dark energy and its implications for cosmic expansion.
  • Discussion includes the role of the Planck satellite in measuring the Hubble constant and its potential impact on understanding the universe's fate.
  • Questions arise regarding how gamma-ray burst observations might indicate changes in dark energy density.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the future of the universe, with no consensus on whether a Big Crunch or Big Rip is more likely. There is also disagreement about the interpretation of evidence related to dark energy and cosmic expansion.

Contextual Notes

Limitations in the discussion include unresolved assumptions about the nature of dark energy, the interpretation of observational data, and the implications of future cosmic scenarios. Some participants express skepticism about the methods used in recent studies.

Who May Find This Useful

Readers interested in cosmology, the fate of the universe, and the implications of dark energy may find this discussion relevant.

trichop
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According to the Big Bang scenario, after the "explosion" , matter and radiation spreads, while the newborn space grows.
My question is:
This firstly emmited radiation (which I think was spread radially, right?)
shouldn't somewhere in time be attracted back, due to the gravity effect?
Does this make any sense?
 
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Yes, in the far distant future, everything will come back in a "Big Crunch".
 
DaveC426913 said:
Yes, in the far distant future, everything will come back in a "Big Crunch".
when there's this "big crunch", don't you think there will be a big bang again?
but this time with some reason? hmm...this get's me to another question...right now we (scientists) think that nothing happened before the big bang. but what if there was a universe and there was a big crunch thus resulting in a big bang...?
 
That is one hypothesis, yes.

BTW, it's not that scientists think there was nothing before the Big Bang, it's that scientists don't study what came before the Big Bang - there's nothing to study. That's the realm of philosophers and theologians.
 
DaveC426913 said:
Yes, in the far distant future, everything will come back in a "Big Crunch".

Current interpretation of observational evidence indicates that this is very unlikey - cosmologists think that the expansion is accelerating, not slowing down.

Some physicists even speculate (wildly?) that if the acceleration accelerates, then there might be a "Big Rip".

Regards,
George
 
George Jones said:
Current interpretation of observational evidence indicates that this is very unlikey - cosmologists think that the expansion is accelerating, not slowing down.

Some physicists even speculate (wildly?) that if the acceleration accelerates, then there might be a "Big Rip".

Regards,
George
well, because big bang was an explosion things heated up and are expanding. but don't you think they will cool down and contract thus resulting in a 'big crunch' rather than a 'big rip'?
 
varsha said:
well, because big bang was an explosion things heated up and are expanding. but don't you think they will cool down and contract thus resulting in a 'big crunch' rather than a 'big rip'?

Current interpretation of observational evidence (mainly) from Type Ia supernovae indicates that the expansion is accelerating. Physcists think that the cause of the acceleration is dark energy/cosmological constant. I am not completely convinced by this evidence that dark energy/cosmological constant exists, but I do find the evidence to be suggestive.

I do not find the evidence for a Big Rip to be nearly so suggestive, but ths is something that I would like to look into in more detail. Results from the study of gamma-ray bursters recently presented give somewhat weak evidence that not only is the universe accelerating, but that the acceleration itself is increasing.

Sean Carroll has a nice discussion of the future of the universe over on the blog Cosmic Variance. The gamma-ray stuff is discussed in the first link in this article.

Regards,
George
 
I recently added a post to my Review of Mainstream Cosmology that directly addresses some of these issues.

George Jones said:
I do not find the evidence for a Big Rip to be nearly so suggestive, but ths is something that I would like to look into in more detail. Results from the study of gamma-ray bursters recently presented give somewhat weak evidence that not only is the universe accelerating, but that the acceleration itself is increasing.

They announced this at the recent AAS and further review suggests that there are some serious problems with their methods of data analysis. I would approach this result with extreme skepticism for the time being.
 
As I understand it, there's a satalite being sent up called plank...One of the experiments on board is to determine the value of 'h' the Hubble constant. Once 'h' is determined then we'll know which way the universe will go.

Please correct me if I'm wrong...It's been years.

Frizz
 
  • #10
Frizz said:
As I understand it, there's a satalite being sent up called plank...One of the experiments on board is to determine the value of 'h' the Hubble constant. Once 'h' is determined then we'll know which way the universe will go.

Among many other things, yes, the Planck satellite is expected to give an accurate measurement of Hubble's constant. It's a CMB mission like WMAP, but it's looking at anisotropies on smaller angular scales. Here's a description of the science goals from the Planck website:

The Planck Mission
 
  • #11
Some observations, including the new gamma-ray-burst results, show a tiny preference for an increasing dark energy density


how do they know that there is an increase in the density of the dark energy with the help of gamma-ray-burst results?
 

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