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Does Matter Evaporate ?

  1. Jul 20, 2008 #1
    Does Matter "Evaporate"?

    I'm wondering if Matter always exists since the big bang or if matter over time "evaporates". I'm not sure if "evaporate" is the right term, but I don't know of a better word. Basically I mean: It's transfered into energy, never to be matter again.

    Does that happen?

    And if so, does that mean that there was more matter in the universe in the past than there is now?

    Could the effects of more matter in the past explain why we think there is more matter in the universe than we can see?
  2. jcsd
  3. Jul 22, 2008 #2
    Re: Does Matter "Evaporate"?

    The formation of rocky planets in new solar systems generates heat without the need for chemical and nuclear reactions. The heat is emitted as a net power, energy lost to space in the form of radiation. However, since photons do not carry charge, conservation of charge dictates that the charge must stay within the gravitational system, unless otherwise ejected by collisions or explosions. Given that and E=mc^2, there must be a mass loss occurring independently of charge loss, meaning that the mass to charge ratio falls very slowly over time.
    Last edited: Jul 22, 2008
  4. Jul 22, 2008 #3


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    Re: Does Matter "Evaporate"?

    I don't know why you think the heat results from direct conversion of mass to energy. It doesn't. The vast majority of the heat released when a solar system forms comes from friction as the matter is compressed by gravity. A small amount probably comes from nuclear fission but it's a very small amount compared to the frictional component.

    There is a small mass loss occurring all the time from the fusion reactions in stars. It's very small though, ppb at the most. While you are correct that photons don't carry charge the mass loss doesn't create any additional charge. So there's no change in mass to charge ratio.
  5. Jul 22, 2008 #4


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    Re: Does Matter "Evaporate"?

    Yes, there is some mass loss as stars fuse hydrogen into heavier elements plus energy (radiation). It is a very small loss though. The mass lost this way is likely only parts per billion of the total mass.

    For example, our sun loses something like 3 million tons per second. However the sun has been fusing hydrogen for 4.5 billion years and probably will for 4 or 5 billion more. The loss is insignificant.

    In a way, yes. If you consider the universe from when hydrogen first formed as a stable (cold) gas then there has been a very very small loss of mass. Very early in the life of the universe though there was no matter at all. Just energy in the form of massless radiation.

    No. The amount of mass loss is so small it simply makes no difference to the total mass of the universe all the way back to when hydrogen first formed.
  6. Jul 22, 2008 #5
    Re: Does Matter "Evaporate"?

    The reason for mass loss due to friction is simple. Energy is lost in the form of radiation. Since a bounded gravitational state is in a lower energy state than a higher gravitational state, it must result in an increase in entropy. In other words, net energy is lost by the gravitational system in the form of energy. This energy, divided by the speed of light squared, is equal to the mass lost during formation. That is a pure logical deduction from Einstein's famous equation, E=mc^2.

    That there is very little change and thereby concluding that there is no change, is bad logic. No change = zero change. Little change > or = zero change. Do not twist the English language to suit your opinion. Even worse, you contradict yourself, saying that a mass loss does not lead to a charge loss, but a mass loss is exactly what you describe as happening in the sun, and because the mass can be lost in the universe, but charge in the universe is conserved, implies directly the opposite of what you claim. In other words, the charge-to-mass ratio is not fixed.
    Last edited: Jul 22, 2008
  7. Jul 23, 2008 #6


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    Re: Does Matter "Evaporate"?

    Please elaborate a bit on this statement;
    Do you mean that mass can get "lost" in (the vastness of) the universe, or that mass can be lost from the universe (annihilated)?
  8. Jul 23, 2008 #7
    Re: Does Matter "Evaporate"?

    I'm saying the mass is converted into energy, and therefore is essentially lost from the universe (annihilated). This happens every time a bounded system reaches a lower energy state. Its very essence is a heat releasing event, going hand in hand with mass loss (equal to the energy of emitted radiation/squared speed of light).
    Last edited: Jul 23, 2008
  9. Jul 23, 2008 #8
    Re: Does Matter "Evaporate"?

    It is my understanding that the equation works in both directions. It is an equivalence describing the relation of two different forms of the same thing. When mass is converted to energy and visa versa, conservation laws still hold. That I think was the main idea behind as to the significance of the relation.
  10. Jul 23, 2008 #9


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    Re: Does Matter "Evaporate"?

    Sure there's energy being radiated from the system but it's gravitational energy that's converted to heat through friction, not mass being converted to energy. The mass of the system will be the same after collapse as before (ignoring any mass blown out of the system by stellar winds after the proto-star starts fusing hydrogen).

    There is no mass lost during formation. E=mc^2 does not imply that all energy comes from mass annihilation.

    It's perfectly good logic when the change in question is on the order of ppb or less. For the current question 'is the universe losing mass' it's safe to say 'not to any appreciable degree'.

    I did not twist the language at all and I'm not expressing an opinion. What I said can be backed up with references to mainstream literature. And do me a favor and lose the snotty attitude.
  11. Jul 23, 2008 #10
    Re: Does Matter "Evaporate"?

    a little off topic, but we can create energy by destroying mass in fission and fusion...

    not that its of any practical use but is it possible with our current technology to create mass from energy?
  12. Jul 23, 2008 #11
    Re: Does Matter "Evaporate"?

    Great discussion everybody. I'm learning new things here (new for me of course.. :) )

    About that ppb mass loss. It seems small but what's the ratio? 1 ppb over how many years?

    Any ideas if that mass loss has always been at the same rate? I can imagine that when the universe was hotter, it was losing mass at a much higher rate than now.

    Also, just to make sure I understand it all.... I'm talking about the loss of mass in the sense that the mass completely dissapeared. Not that it radiated away in the form of small particles. I'm hoping to find out if the gravitational effect of that mass is also gone.
  13. Jul 23, 2008 #12


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    Re: Does Matter "Evaporate"?

    Hi Peter. I should clarify my previous statement. When I said the mass loss in fusion was on the order of magnitude ppb I was thinking of the mass loss between two protons when converted to helium. That grossly overstates the mass loss as a fraction of the Suns mass. As a fraction of the Suns mass it comes to something like 1 part in 10^21. That is so negligible as to be ignored for all intents and purposes. That's why the Sun can 'burn' 3 million tonnes of hydrogen every second but last for 10 billion years.

    The universe has been losing that insignificant amount of mass since the first stars formed. But I hope you can see that even with all the stars fusing matter for all the seconds the universe has existed the mass loss still doesn't amount to more than a few ppb. That's over the whole history of the universe since stars first formed.

    In earlier times when the universe was much hotter mass was both lost through fusion and formed through pair production. Earlier (and hotter) still there was no matter.
  14. Jul 23, 2008 #13
    Re: Does Matter "Evaporate"?


    http://www.journals.uchicago.edu/cgi-bin/resolve?ApJ52134 (google result)

    Last edited by a moderator: Apr 23, 2017
  15. Jul 23, 2008 #14
    Re: Does Matter "Evaporate"?

    Now I wonder what's the overal result of this mass loss to space density. Does loss of mass mean loss of gravity as well? I mean in the sense that space just got a little denser because there's less mass pulling on it from all sides?

    If space gets denser, light travels slower through it. Not when measured locally, but for an theoretical observer outside that space time frame, the light would move slower and locally it would seem like distances are increasing,... ie. expanding space.

    Does it make any sense that loss of mass results in higher density of space which makes it look like distances are increasing?
  16. Jul 24, 2008 #15
    Re: Does Matter "Evaporate"?

    -Refering to that article... what the hell is "rest mass energy?" as far as i know there is rest mass which is your mass not including energy and there is relativistic mass which is the mass and the energy. correct me if im wrong... it is early in the morning ;-)

    -Peter... im not sure exacly what your talking about... light travels the same speed in a vacuum no matter what, whether the universe is expanding or contracting... and im not sure how it makes sense that if the universe was expanding and distances getting larger how it would result in higher density... i think your getting things mixed up
    Last edited: Jul 24, 2008
  17. Jul 24, 2008 #16
    Re: Does Matter "Evaporate"?

    rest mass energy = rest mass * speed of light squared

  18. Jul 24, 2008 #17
    Re: Does Matter "Evaporate"?

    alrighty then... on my way to get another coffee haha

    so some of its mass was directly converted into energy... but how does this energy create gravity waves... i thought mass distorts space-time to make gravity
    Last edited: Jul 24, 2008
  19. Jul 24, 2008 #18
    Re: Does Matter "Evaporate"?


    Maybe I am. I just don't understand yet how I have things mixed up so what I'm asking still makes sense to me. This is why I started this thread to understand where I'm going wrong.

    Actually I don't think that the result would be a higher density. It's the other way around. The higher density results in expanding space. What I'm thinking is that the more mass there is, the less dense space is because the space density is concentrated around the mass.

    If, over time, mass dissapears in the universe, space gets slowly denser. and so light travels slower through it. If you´re in space too (we all are) then you don't notice this because relativy tells us that the speed of light is always the same. Well if the speed of light is always the same, then something else has to give. My conclusion is: space is expanding.

    Are we able to measure space density? I heard somewhere that empty space actually contains a lot of energy. If we can measure it, can we also measure if it is changing and see if that goes at the same rate as the expansion of space?
  20. Jul 24, 2008 #19
    Re: Does Matter "Evaporate"?

    im having a little trouble understanding your logic... first off, you probably just worded this wrong but mass does not dissapear... i think some of your lingo is just confusing... i think your getting at that space-time itself is more dense because you have less mass but im not sure if that is really even realistic... but i think you have it backwards... if there is less mass then the earth is making a smaller dent in the space-time fabric allowing it to stretch out a little more relatively speaking which would make space-time less dense in a sense if you think about it in the bowling ball on a trampoline analogy... (im not sure if thats realistic to say because space-time is thought to be "nothing" really and im not sure if nothing can have a density)

    so this kinda makes sense but im not sure if this is really why the universe is expanding... it makes sense in that the distances are getting larger because the decrease in mass is allowing the the space-time fabric to expand... but i think the literal interpretation is that space-time itself is limitless and that galaxies and solar systems are moving away from each other. so your interpretation could be relatively true but i dont think its the main reason the universe is expanding
  21. Jul 24, 2008 #20
    Re: Does Matter "Evaporate"?

    I'm sure I'm having difficulties wording it right. I don't have all the terminology and english isn't my native language, but I hope I can somehow express myself clear enough to get the point accross. :)

    Here's a thing I thought about a lot:

    You have a black hole at a certain distance from you. Suppose there is a light source really close to the black hole, but still outside the horizon so it can escape and reach you. On your other side, at the same distance there is another light source.

    As I understand it, those 2 light beams are not going to reach you at the same time. The one from near the black hole will reach you later. It moves slower through the much denser space near the black hole. (but if you'd measure it at various points on the line of sight, you'd measure the speed of light of course.) But if we could measure the speed of light from where we are but at those same points in the line of sight, we would measure a slower speed. We have to measure a slower speed because we know how far away the black hole is and if the light took longer to reach us while the distance is the same, then the only thing that changed is the speed of light.


    the distance between the horizon and us is longer.

    How far would we think that light source is away from us if we would be looking through a tube and could only see the light source with nothing but the black hole behind it?

    In that specific case, wouldn't it seem like that that light source is much further away from us? Since we don't have any reference points other than the light it self.

    So space density is much higher (I think) near a black hole. I'm calling it denser because light travels slower through it (not when measured locally of course).

    This all feels exactly the same as the explanation I read somewhere that a star that emitted its light to us from a distance of 40 million light years, in the very young universe, only reaches us now, 13 or so billion years later, while that same star now would be 46 or so billion light years away from us. The expansion of space made that light take 13 billion years to get here, because space expanded,.


    because space got denser and the light constantly slowed down. Since we will always measure c to be the same, the only conclusion can be that the distance between the star and us grew. But you can just as well say that space got denser and the light slowed down because of it.

    Does this make any sense?
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