Proton-electron mass ratio; changed? how much?

  • #1
5
0

Main Question or Discussion Point

On the subject of our 'finely turned universe', I have read that the proton-electron mass ratio can not deviate more than 1:1037. In other readings, the allowable deviation was stated as 1% ("If the neutron were very slightly less massive, then it could not decay without energy input. If its mass were lower by 1%, then isolated protons would decay instead of neutrons, and very few atoms heavier than lithium could form."

Scientists using a Effelsberg 100-m radio telescope have determined that the ratio has changed "by only one hundred thousandth of a percent or less over the past 7 billion years"; alternatively, the change is written as 10^-7.

My question is: Is the change in the ratio (one hundred thousandth of a percent, 10^-7) greater or less than 1:1037?

[1:1037 is 1:10 to the 37th power]
 

Answers and Replies

  • #2
Vanadium 50
Staff Emeritus
Science Advisor
Education Advisor
2019 Award
24,776
7,771
On the subject of our 'finely turned universe', I have read that the proton-electron mass ratio can not deviate more than 1:1037.

[1:1037 is 1:10 to the 37th power]
I'm sorry, but that is simply not correct.
 
  • #3
5
0
Has the maximum deviation of the protron-electron mass ratio been calculated? If so, what is it? Is it something less than 1%?
 
  • #4
jtbell
Mentor
15,584
3,561
I have read
Where?

that the proton-electron mass ratio can not deviate more than 1:1037.
Do you mean 1037 (one thousand thirty-seven), or 1037 which is a really really really big number, or 10-37 which is a really really really small number?

(Tip: to write exponents correctly, highlight them with the mouse, then click the "x2" icon in the toolbar at the top of the message editor.)
 
  • #5
5
0
My lack of physics/math background is showing.

The number would have to be small since the article I read was speaking on the subject of a finely tuned universe and how a slight deviation in the ratio would not support the creation of the universe as we know it.

This would seem to be the equation, 1:10-37.

Thanks, jtbell, for the tip.
 
  • #6
Vanadium 50
Staff Emeritus
Science Advisor
Education Advisor
2019 Award
24,776
7,771
Has the maximum deviation of the protron-electron mass ratio been calculated? If so, what is it? Is it something less than 1%?
It's measured, not calculated. And it's known to half a part per billion - which is precise, but nowhere near as precise as your 10-37. Since it's not known to 10-37, it's hard to argue that it's value matters at the level of 10-37.
 
  • #7
Grinkle
Gold Member
674
187
If you can still recall where you read it (something I often struggle with) post the specific reference and you will almost certainly get more help understanding what you read.
 

Related Threads on Proton-electron mass ratio; changed? how much?

Replies
6
Views
934
  • Last Post
Replies
6
Views
1K
Replies
4
Views
4K
  • Last Post
Replies
6
Views
3K
Replies
1
Views
3K
Replies
3
Views
2K
Replies
5
Views
13K
Replies
1
Views
2K
Replies
4
Views
3K
Replies
1
Views
692
Top