Is the Universe Losing Mass?

1. Jan 21, 2005

Les Sleeth

I am thinking mostly about all that heat released in stellar activity, but any insights about this might help resolve a little debate I'm having with a friend.

2. Jan 21, 2005

Enos

It's logical to say that if the universe is accelerating. Less mass equals more energy and faster acceleration.

3. Jan 21, 2005

Integral

Staff Emeritus
Heat loss? To where? If the universe had some where to lose heat to, it would be part of the universe. Pretty much by definition of the universe, it cannot loose mass.

Similar argument for acceleration or any other form of motion. The Universe cannot move because it has no where to move to.

Keep in mind that the universe consists of all observed and all observable space/time.

4. Jan 21, 2005

The Bob

I would say that Mass is Energy, therefore, the universe is not losing mass because to lose energy is to destroy it and that is not possible. Therefore the universe is not losing mass.

P.S. I think the two laws I am referring to are the first two laws of thermodynamics (but do not hold me to that).

5. Jan 21, 2005

Les Sleeth

Here's what I don't understand. To say mass has energy, or that mass and energy are equivalent, doesn't mean energy and mass are exactly the same thing does it? If energy and mass are the same thing, then why are there two different terms for them? Doesn't one increase or decrease at the expense or gain of the other?

Just a little more clarification of my question (and confusion). Even if energy and mass are the same thing, don't the two terms indicate different conditions? Say we had a perfect closed situation where no energy could escape. We burn a piece of wood. In that closed environment, would it be proper to say the mass "condition" decreased and the energy "condition" increased?

Last edited: Jan 21, 2005
6. Jan 21, 2005

Staff Emeritus
Mass can, under certain conditions, be converted to energy. Energy can, under certain other conditions, be converted into mass. When none of these conditions apply, they are different.

7. Jan 21, 2005

Les Sleeth

Dare I ask? Under the current conditions in our universe, is it proper to say that mass is being converted to energy at a higher rate than the reverse, and therefore overall mass is becoming less available (than it used to be) for . . . ?

8. Jan 21, 2005

Labguy

I would think so. It is true that mass/energy total will remain the same, but mass and energy are just two forms of "an entity". We could have all matter and no energy or all energy and no matter, but either is unlikely.

First law of Thermodynamics is (basically) that the total can change but will remain the same. Second law (Entropy) is what you are suggesting by matter, stars, etc. being converted into energy. This doesn't violate the first law and does conform with the second law.

9. Jan 22, 2005

Orion1

I believe that it is more 'meaningful' to state that the total Universe Entropy equation of state is increasing towards disorder, therefore, with this understanding, the original topical question becomes irrelevant.

Last edited: Jan 22, 2005
10. Jan 22, 2005

Chronos

The equivalancy principle makes no distinction between mass and energy, energy is just more diffuse. In GR, they are treated as the same.

Last edited: Jan 22, 2005
11. Jan 22, 2005

Labguy

True. My post would have been more appropriate if the question would have said matter/energy instead of mass/energy...

But, Hawking wrote that there is no "real" meaning for the word mass other than simply "a quantity of matter". I wonder if we could also say "a quantity of energy"? Doesn't sound right that way, somehow.

From Sleeth's second post, second paragraph, it actually sounds as if he is meaning "matter" instead of mass. The burning wood example, for instance. (?)

Last edited: Jan 22, 2005
12. Jan 22, 2005

Mike2

Are we losing both mass and energy as galaxies disappear behind the cosmological event horizon? IIRC we do not see anything in our present light cone disappearing behind the cosmological event horizon. But we are looking into the past at distant galaxies. Yet what about the event horizon as it exist today. Though we may not see it yet, are distant galaxies leaving our field of vision and influence due to the expansion of the universe? Thanks.

13. Jan 22, 2005

Les Sleeth

Let me explain the part of my discussion with someone that led to my question. I suggested that the universe's mass was decreasing, he said it was just being more dispersed, as Chronos said. I could see that except for heat.

In wood burning, for example, photons are sent flying off. With that kind of dispersion one could say the universe is becoming less dense rather than less massive. The photons possess an energy level as a discrete particle. To me, the little package that holds the energy (a particle) is what maintains mass.

But in that wood burning, heat is given off too, and heat isn't retained like energy is in particles is it? It won't stay neatly contained within particles, but will continue to disperse. So to me it seems like heat dispersion signals an entropic altering of the ratio of energy to mass in the universe.

That's what I meant by asking that, if there is no difference between energy tied up in a particle and that which appears to have been set free to disperse forever, then why are there two different terms (mass and energy)? Isn't part of the meaning of mass a certain discreteness or quantumness?

14. Jan 22, 2005

Labguy

Since you said "tied up in a particle" it appears you mean matter (particles) vs energy (=mass). If that is the case, then I would think that all the answers posted above are correct. Some about mass, some about matter, but the bottom line is entropy.

15. Jan 23, 2005

Chronos

Heat makes particles move. Kinetic energy is the lowest form of energy. Energy is not lost because particles gain momentum from it. They subsequently transfer that momentum to other particles with which they collide.

16. Jan 23, 2005

Labguy

Ok,.........,but; to what above does this statement apply??

17. Jan 24, 2005

Chronos

Heat loss. Heat energy is radiated [in the infrared spectrum] until it is imparted to a massive particle causing it to move, or kick an electron into a higher energy state. Eventually it is all translated into kinetic energy.

18. Jan 24, 2005

Les Sleeth

You are describing exactly what I was questioning if it is true. If you will bear with me for another question, I'll explain what I've read that's made me wonder if the universe is losing mass.

First, what I really mean by the universe "losing mass" is to ask if the energy of particles in the universe is decreasing overall in relation to "free" energy (i.e., energy not absorbed/affecting particles of any sort).

According the article found http://www.space.com/scienceastronomy/missing_matter_030212.html [Broken], within galaxies and local groups is a hot gas. An excerpt from the article says:

“A vast fog of hot gas infusing the space between galaxies has been firmly detected, apparently filling in an important blank in the cosmic ledger involving up to 80 percent of normal matter. . . . The gas surrounds our own galaxy and appears to weave through about three dozen others that make up what's called the Local Group of galaxies. . . . In all, the gas makes up a giant cloud, estimated to weigh a trillion times more than our Sun, all surrounding the Local Group. . . .The gas is widely dispersed and 150 times hotter than the Sun's surface, making it practically invisible. It could only be detected by the most advanced space-based observatories, and three of them were needed to do the job.”

Chronos, in your answer, "Heat energy is radiated . . . until it is imparted to a massive particle" you seem to say that all radiated energy will be eventually reabsorbed by particles. Considering the excerpt above, your answer makes sense within local groups of galaxies.

However, supposedly the universe is 65% dark energy which exists between the galaxy clusters (see diagram 1 below, taken from one of the links embedded in the article). If local groups are radiating heat energy (especially that hot), then isn't some of it radiating into the vast areas of space between clusters of galaxies where there is no observed matter? Doesn't that, combined with the increasing rate of expansion of the universe (see diagram 2), suggest the ratio of free (dark?) energy is increasing in relation to that energy associated with particles?

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