Universe mass?

[alpha2cen]

The Universe radiates much electromagnetic waves to all direction.

So the mass should be decreased at every second.

Can we calculate the total mass?

And, how about the decrease rate per second?

[Arch2008]

Objects in the universe, like stars, convert matter into energy that gets radiated into space. Matter with mass X is converted into energy with mass X. If you took an arbitrary mass for a star and calculated the average mass of a galaxy then you could approximate the mass of one hundred billion galaxies to get the mass of the observable universe. (This might be approximately something like 10^11 solar masses squared or 10^22 solar masses) However, the total universe (the observable plus whatever else there is) is a closed system. The energy in the total universe is not radiated into something else, i.e., the universe is everything. So the mass of the total universe stays the same and does not decrease.

Edited December 28, 2010 by Arch2008

[alpha2cen]

The problem is the definition of the mass.

mass1 ---------------------> mass2 + electromagnetic wave energy

.

mass1 energy = = mass2 energy + electromagnetic wave energy . This equation is correct.

But

mass1 = mass2 + electromagnetic wave energy ???

Are there anything I didn't think about?

[Arch2008]

If I understand you correctly, then you have a starting mass1 which undergoes some unspecified process to radiate energy in the electromagnetic spectrum and becomes mass2. To better elaborate this relationship, I might use terms like mass1 and something like mass1’ (mass1 prime). Other than that, it looks okay to me.

[alpha2cen]

If total mass were not changed in the Universe, there would be some place which absorb the emitted electromagnetic wave.

Homogeneously distributed Black hole would be one of the ways.

If not, the Universe mass should be decreased continuously.

[Arch2008]

If there were some place for the EM to radiate away from the universe, then the primordial universe that was extremely hot would have rapidly radiated away to nothing. The universe is a closed system. Space is expanding and the further you go from any given point the greater the rate of expansion. At a certain point, the space in between is expanding faster than the speed of light. So EM radiation from the Sun will never escape the universe, because it only travels at the speed of light. This same situation exists for every other star and every other point in the universe.

Edited December 30, 2010 by Arch2008

[Widdekind]

If the critical density is [math]\rho_c \approx 10^{-26} kg \, m^{-3} \approx 4.3 \times 10^{18} M_{\odot} \, Gly^{-3}[/math], and if our closed Cosmos contains around 10 million cubic giga-lightyears of spatial volume, then that amounts to a mass of roughly [math]5 \times 10^{25} M_{\odot}[/math].

[alpha2cen]

If the critical density is [math]\rho_c \approx 10^{-26} kg \, m^{-3} \approx 4.3 \times 10^{18} M_{\odot} \, Gly^{-3}[/math], and if our closed Cosmos contains around 10 million cubic giga-lightyears of spatial volume, then that amounts to a mass of roughly [math]5 \times 10^{25} M_{\odot}[/math].

 

Thank you for good answering.

How do we calculate the critical density?

From the stellar number?