Some questions for want of answers:

  • Context: Graduate 
  • Thread starter Thread starter Naveen345
  • Start date Start date
Click For Summary

Discussion Overview

The discussion revolves around the existence and nature of black holes and singularities, particularly focusing on the duration of black holes and the state of the singularity before the Big Bang. Participants explore theoretical implications, mathematical interpretations, and the philosophical aspects of time and existence in cosmology.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants propose that black holes grow by acquiring mass and shrink through Hawking radiation, suggesting that their lifespan depends on mass and evaporation rate.
  • Others argue that time did not exist before the Big Bang, leading to the idea that the singularity could be said to have always existed or to have existed for no time at all.
  • A participant questions the existence of a singularity before the Big Bang, suggesting that it may not be a real entity but rather a reflection of incomplete understanding in cosmology.
  • Some assert that there was time before the Big Bang, although they describe it as extremely insignificant, referencing Stephen Hawking's work.
  • There is a contention regarding the validity of mathematical proofs in physics, with some participants asserting that rigorous mathematics cannot definitively prove physical realities, especially concerning singularities.
  • Concerns are raised about the reliability of mathematical results without empirical validation, emphasizing the need for testing mathematical conclusions against physical observations.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the existence of singularities and the nature of time before the Big Bang. The discussion remains unresolved, with no consensus on these complex topics.

Contextual Notes

Limitations include the dependence on definitions of time and singularity, as well as the unresolved nature of mathematical interpretations in relation to physical phenomena.

Naveen345
Messages
19
Reaction score
0
1. How long does a black hole exist?
2. How long did the singularity exist before the big bang?
 
Space news on Phys.org
1. How long does a black hole exist?
Black holes grow as the acquire mass from infalling material and shrink slowly through Hawking radiation. A BH will 'evaporate' when it can no longer gain mass. How long that takes will of course depend on the mass of the BH and the rate of evaporation.

2. How long did the singularity exist before the big bang?
Time itself did not exist before the big bang. You can say the singularity *always* existed, and that it existed for no time at all, and be correct both ways.
 
tadchem said:
2. How long did the singularity exist before the big bang?
Time itself did not exist before the big bang. You can say the singularity *always* existed, and that it existed for no time at all, and be correct both ways.

Similarly, one might say either that the north pole exists everywhere greater than or equal to 90 degrees north latitude or that the north pole exists only at 90 degrees north latitude.

Since there's nothing north of the north pole, both are equivalent.
 
Last edited:
Naveen345 said:
2. How long did the singularity exist before the big bang?

Unknown. There may not have even been a singularity, and I know one of our Cosmology experts claims that practically no professional Cosmologist actually believes that the singularity predicted in the theory is real. Instead it is believed to be the result of our incomplete knowledge of how physics works at that scale.
 
Naveen345 said:
1. How long does a black hole exist?
2. How long did the singularity exist before the big bang?

There WAS time before the big bang, but it is extremely insignificant. Read on A Brief History of Time by Stephen Hawking which delves into this very concept.
 
Bboy Physics said:
There WAS time before the big bang, but it is extremely insignificant. Read on A Brief History of Time by Stephen Hawking which delves into this very concept.

Maybe we should stick to generally accepted consensus as opposed to speculation?
 
Whovian said:
Maybe we should stick to generally accepted consensus as opposed to speculation?

when a singularity can exist at the centre of a black hole ( this is what rigorous mathematics proves), what can't it exist before the big bang?
 
Naveen345 said:
when a singularity can exist at the centre of a black hole ( this is what rigorous mathematics proves), what can't it exist before the big bang?

Those rigorous mathematics are most likely wrong. It is probable that we don't know how physics works at the scale of black holes, causing our math to cease to accurately represent reality. Remember, there are no "proofs" when it comes to describing the real world. Only pure mathematics has proofs.
 
Naveen345 said:
when a singularity can exist at the centre of a black hole ( this is what rigorous mathematics proves), what can't it exist before the big bang?
Nonsense. "Rigorous mathematics" cannot prove anything about physics. And I doubt that any intelligent mathematician would want to express an opinion as to what a mathematical "singularity" would mean physically.
 
  • #10
No one should believe the result of some Maths without testing its validity. Even the simplest SUVAT calculations can give you an impossible answer if you don't take the right sign for the square root.
 
  • #11
sophiecentaur said:
No one should believe the result of some Maths without testing its validity. Even the simplest SUVAT calculations can give you an impossible answer if you don't take the right sign for the square root.

No wonder my GPS took me to Rhode Island. I knew I should have turned right at Albuquerque.
 

Similar threads

Undergrad Shouldn't the Big bang be physically impossible?
  • · Replies 25 ·
Replies
25
Views
4K
Undergrad Is the Big Bang Actually a White Hole?
  • · Replies 22 ·
Replies
22
Views
5K
Undergrad Post Big Bang Gravity
  • · Replies 11 ·
Replies
11
Views
3K
Undergrad Question about the big bang singularity
  • · Replies 13 ·
Replies
13
Views
5K
Undergrad Questions about the Location of the Big Bang and the Age of the Universe
  • · Replies 8 ·
Replies
8
Views
3K
Undergrad Proton decay at the end of the Universe
  • · Replies 13 ·
Replies
13
Views
3K
Undergrad Some questions about Cosmic Inflation
  • · Replies 4 ·
Replies
4
Views
5K
Undergrad Relativistic Reference Frames and the Big Bang?
  • · Replies 6 ·
Replies
6
Views
2K
Undergrad What Triggered the Big Bang Singularity's Expansion?
  • · Replies 15 ·
Replies
15
Views
6K
Undergrad Some questions regarding the initial singularity
  • · Replies 4 ·
Replies
4
Views
2K