# B The Proton and Entropy

#### Gfellow

Summary
How does one reconcile the non-decaying Proton and the Law of Entropy?

I am sure this subject has come up many times before, and could well be a stupid question. If so, could you direct me to the relevant thread(s)?

Setting aside its itinerant electron, (Hydrogen Atom,) the Proton is THE building block of the Universe.

"...Despite significant experimental effort, proton decay has never been observed..."
~Proton Decay, Wikipedia

How does this jibe with the Law of Entropy?
Can someone explain?

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#### Dale

Mentor
How does this jibe with the Law of Entropy?
What makes you think that it conflicts? I don’t see the connection.

#### Gfellow

I'm wondering, if everything winds down, what about the Protons? Do they decay?

#### Dale

Mentor
I'm wondering, if everything winds down
The second law of thermo says that the entropy of an isolated system never decreases.

what about the Protons? Do they decay?
No. There is nothing for them to decay into.

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#### Gfellow

So in an entropic universe is still smack-full of as many protons as it started out with, they're merely rushing away from each other?

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#### davenn

Gold Member
So in an entropic universe is still smack-full of as many protons as it started out with
As far as I'm aware of, yes

they're merely rushing away from each other?

Why do you think they would be doing that?
Are all the protons in your body doing that ?

#### Ibix

I'm wondering, if everything winds down, what about the Protons? Do they decay?
The problem here seems to be that you are mis-stating the second law of thermodynamics. It says entropy in a closed system never decreases, not that it always increases (which is what your "everything winds down" would seem to imply). We have no problem with things not changing.

In fact, if we insist that protons must decay just because "everything decays" then this doesn't solve your problem. If protons did decay into something, what would that something do? If it doesn't decay then observing a proton decaying simply pushes your problem back a step. If it does decay you can ask the same question about its decay products, rinse and repeat. Either you have to accept something that doesn't decay, a circular decay chain (which would very likely violate the second law) or an infinite decay chain (which doesn't seem very parsimonious).

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#### anorlunda

Mentor
Gold Member
I'm wondering, if everything winds down
That sounds like the root of your confusion. I'm not sure what you mean by winds down.

You may be mixing up the 2nd Law (as others already said), and the postulated ultimate heat death of the universe (https://en.wikipedia.org/wiki/Heat_death_of_the_universe). They are not connected. And proton decay is not connected with either of them.

#### Gfellow

They are not connected. And proton decay is not connected with either of them.
Does this mean that when talking about the Heat Death of the Universe, we can ignore the non-decay of the proton?

#### Gfellow

That sounds like the root of your confusion. I'm not sure what you mean by winds down.

You may be mixing up the 2nd Law (as others already said), and the postulated ultimate heat death of the universe (https://en.wikipedia.org/wiki/Heat_death_of_the_universe). They are not connected. And proton decay is not connected with either of them.
Since radiation travels at the speed of light and Protons do not, and if Protons do not decay, would that infer that an expanding Heat Death Universe would consist of a core of relatively slow proton outflow while the radiation of the Universe has left the Protons behind?

#### Gfellow

In fact, if we insist that protons must decay just because "everything decays" then this doesn't solve your problem. If protons did decay into something, what would that something do?
If a Proton did decay, wouldn't it result in an emission of radiation, a release into the entropic system described in the Third Law of Thermodynamics, contributing to the Heat Death Universe, whereas a non-decaying Proton would not?

#### Dale

Mentor
I am not convinced that the non-decay of a proton is relevant here. What does not decay is an isolated proton. The heat death of the universe will have lots of opportunities to interact with things to allow decay.

#### ZapperZ

Staff Emeritus
2018 Award
Summary: How does one reconcile the non-decaying Proton and the Law of Entropy?

I am sure this subject has come up many times before, and could well be a stupid question. If so, could you direct me to the relevant thread(s)?

Setting aside its itinerant electron, (Hydrogen Atom,) the Proton is THE building block of the Universe.

"...Despite significant experimental effort, proton decay has never been observed..."
~Proton Decay, Wikipedia

How does this jibe with the Law of Entropy?
Can someone explain?

Back, up, BACK UP a bit here... You have made a HUGE leap in logic.

You made the connection that (1) proton doesn't decay to (2) it must then violate 2nd law of Thermodynamics.

This connection has NOT been established, especially by you! You have made a statement that has no justification, and a logical and rational series of connection between the two is missing!

So before we argue on this, you must make your case, because otherwise, we are arguing about the color of a unicorn's tail, without first establishing that the unicorn even exists! An established paper in a standard peer-reviewed journal should be your starting point, NOT a wikipedia article, thankyouverymuch.

Zz.

#### jbriggs444

Homework Helper
would that infer that an expanding Heat Death Universe would consist of a core of relatively slow proton outflow while the radiation of the Universe has left the Protons behind?
In Big Bang cosmology, the universe does not expand from a center. It expands everywhere. There is no core.

#### mfb

Mentor
Why are you worried about proton decay but not electron decay, which also has never been observed? Or photon decay, which is impossible for very fundamental reasons?

Particles decay if there is a possible decay mode, they do not decay if there is not. As simple as that. If protons cannot decay they will just stay around forever. The expansion of the universe will reduce their density more and more, just as it reduces the density of radiation.

Heat death just means the universe reaches the maximum entropy, it doesn't tell you how this state of maximum entropy looks like.

#### Gfellow

As far as I'm aware of, yes
Why do you think they would be doing that?
Are all the protons in your body doing that ?
My body contains Electrons as well as Protons. If my body consisted merely of Protons, since they are of the same polarity, wouldn't they repel one another?
The electron can decay into a photon and neutrino, the dispersion contributing to the Heat Death of the Universe, but if the Proton doesn't decay, do they just stick around?

#### Dale

Mentor
The electron can decay into a photon and neutrino
No it can’t. Where did you get that idea? That wouldn’t conserve charge.

if the Proton doesn't decay, do they just stick around?
Again, an isolated proton doesn’t decay (so it would stick around), but protons in the universe are not always isolated.

#### Gfellow

Why are you worried about proton decay but not electron decay, which also has never been observed? Or photon decay, which is impossible for very fundamental reasons?
Can't the electron decay into a photon and neutrino?

Particles decay if there is a possible decay mode, they do not decay if there is not. As simple as that. If protons cannot decay they will just stay around forever. The expansion of the universe will reduce their density more and more, just as it reduces the density of radiation.
Over time, with the electrons having decayed into photons and neutrinos, dissipating at the speed of light and contributing to the Heat Death of the Universe, leaving only the slower moving Protons in existence, would the like polarity Protons dispel one another?

Heat death just means the universe reaches the maximum entropy, it doesn't tell you how this state of maximum entropy looks like.
Is maximum entropy an absolute?

#### Gfellow

In Big Bang cosmology, the universe does not expand from a center. It expands everywhere. There is no core.
I think I understand that; would that impact my question concerning Protons in a Heat Death Universe? If so, in what way?

#### Dale

Mentor
Can't the electron decay into a photon and neutrino?
No. It doesn’t conserve charge.

#### Gfellow

Back, up, BACK UP a bit here... You have made a HUGE leap in logic.

You made the connection that (1) proton doesn't decay to (2) it must then violate 2nd law of Thermodynamics.
I was thinking more along the line of the Third Law of thermodynamics

This connection has NOT been established, especially by you!
I feel small and humbled.

You have made a statement that has no justification, and a logical and rational series of connection between the two is missing!

So before we argue on this
I was not arguing, just asking a question from a rich forum of knowledge.

you must make your case, because otherwise, we are arguing about the color of a unicorn's tail, without first establishing that the unicorn even exists! An established paper in a standard peer-reviewed journal should be your starting point, NOT a wikipedia article, thankyouverymuch.
I used the Wikipedia quote for brevity. There is a long history of Proton Decay experiments out there, as can be evidenced by a Google Scholar search:

Sorry if I have in some way offended you

#### Gfellow

Thank you for your time, everyone. I'm very grateful for your responses. I shall not pursue this query here any further.

"The Proton and Entropy"

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