Sun powered by quantum tunneling - question

Click For Summary

Discussion Overview

The discussion centers around the mechanisms of nuclear fusion in the sun, particularly the role of temperature and quantum tunneling. Participants explore the implications of these factors on the sun's stability and longevity, as well as the conditions necessary for fusion to occur.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants assert that nuclear fusion in the sun occurs due to quantum tunneling, allowing fusion to happen at temperatures below the typical threshold of 100 million Kelvin.
  • One participant questions whether the sun would explode if it reached 100 million Kelvin, suggesting that fusion would occur much faster and deplete hydrogen rapidly.
  • Another participant clarifies that the relationship between temperature and fusion is not a strict cutoff, emphasizing that the rate of fusion depends on the fraction of particles with sufficient energy, which varies with temperature.
  • Concerns are raised about the accuracy of sources, with one participant suggesting that Google is not a reliable authority for scientific facts and recommending a Wikipedia article for better context.
  • There is a discussion about the appropriateness of the term "quantum tunneling," with some suggesting that it may be too narrow to describe the complexities of fusion reaction rates.

Areas of Agreement / Disagreement

Participants express differing views on the implications of temperature on fusion rates and the role of quantum tunneling, indicating that multiple competing perspectives remain without consensus.

Contextual Notes

Some claims about temperature thresholds and fusion rates depend on specific fusion reactions and may not apply universally. The discussion also highlights the variability in scientific sources and the importance of referencing authoritative material.

brajesh
Messages
62
Reaction score
15
I recently found out that for nuclear fusion to occur the temperature needs to be around 100 Million Kelvin and that the hottest part of the sun is only at 27 Million Kelvin. And that the reason nuclear fusion is occurring in the sun is because of quantum tunneling—allowing a very small fraction of the hydrogen to fuse to helium even below the 100MK requirement.

Is this correct?
If so, I have a question.

Q - Is this what prevents the sun from blowing up? In other words, if it was at 100MK then all the hydrogen would fuse to helium and the sun would be used up almost all at once right?
 
Physics news on Phys.org
brajesh said:
if it was at 100MK then all the hydrogen would fuse to helium and the sun would be used up almost all at once right?

Certainly a lot faster, yes.
 
  • Like
Likes   Reactions: brajesh
brajesh said:
I recently found out

Where? Please give a specific reference.

brajesh said:
I recently found out that for nuclear fusion to occur the temperature needs to be around 100 Million Kelvin

First, there is not a hard cutoff between "occurs" and "doesn't occur", even without taking quantum effects into account. The temperature is only the average kinetic energy of the particles; the relevant quantity is not whether a particular reaction will occur (such as fusion), but how the rate at which it occurs depends on the temperature, which basically amounts to what fraction of the gas particles at a given temperature will be expected to have energies at or above the threshold energy for the reaction.

Second, the threshold energy, and therefore the rate as a function of temperature, depends on the particular fusion reaction; some reactions have lower thresholds than others. See, for example, the graph towards the end of the "Requirements" section in the Wikipedia article on nuclear fusion.

https://en.wikipedia.org/wiki/Nuclear_fusion#Requirements

brajesh said:
the reason nuclear fusion is occurring in the sun is because of quantum tunneling

"Quantum tunneling" might be too narrow a term. But it is true that reaction rates calculated with quantum effects taken into account are significantly different than reaction rates calculated without them, and that the former are more accurate.
 
  • Like
Likes   Reactions: brajesh
@PeterDonis nice chart, thank you for the explanation.
I googled "what temperature is needed for fusion" and out popped the result "100M celsius"
 
PeterDonis said:
Where? Please give a specific reference.


I think this is after the OP question.
Because I just watch this video and looking explanation in PF Forum.
 
1618797691350.png
 
brajesh said:
Google is many things, but a single authoritative source for scientific facts is not one of them. I have already explained in a previous post what is wrong with the claim shown in the quote above. The Wikipedia article I linked to earlier is a better starting point; also it gives good references to better sources.
 
  • Like
Likes   Reactions: brajesh

Similar threads

  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 8 ·
Replies
8
Views
14K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 29 ·
Replies
29
Views
3K
  • · Replies 114 ·
4
Replies
114
Views
11K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 11 ·
Replies
11
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K