- #1
indie452
- 124
- 0
hi
im doing a question at the moment and am having issues understanding the question, and i can't ask my lecturer as he is stuck abroad with no internet.
the question asks to calculate the ratio of current energy density of CMBR photons to that of baryonic matter.
the present density of baryonic matter in the universe is pm,0=2.56x10-27kg/m3
CMBR Temp = 2.725K
ok so i calculated energy density of the CMBR = 4/c * [sigma]T4 = 0.417x10-13J/m3
sigma=stefans constant
i'm not quite sure how to turn the pm,0 of baryonic matter into an energy density. but i can see it needs to be multiplied by dimensions (m/s)^2
thanks for any hints
also what does pm,0 mean?
im doing a question at the moment and am having issues understanding the question, and i can't ask my lecturer as he is stuck abroad with no internet.
the question asks to calculate the ratio of current energy density of CMBR photons to that of baryonic matter.
the present density of baryonic matter in the universe is pm,0=2.56x10-27kg/m3
CMBR Temp = 2.725K
ok so i calculated energy density of the CMBR = 4/c * [sigma]T4 = 0.417x10-13J/m3
sigma=stefans constant
i'm not quite sure how to turn the pm,0 of baryonic matter into an energy density. but i can see it needs to be multiplied by dimensions (m/s)^2
thanks for any hints
also what does pm,0 mean?