science help plzzzzzzzzzzzzzzz?
posted by centya .
What is the mean photon energy of.......?
During the history of the Universe from the Big Bang to the present day, at some point in time the mean temperature of the Universe was 1 × 10^17 K. What was the mean photon energy at this instant, and which of the four fundamental interactions or three unified interactions were in evidence at this time?
what is the mean photon energy,please write it in scientific notation to a precision of one significant figure,
The mean photon energy was = ??? eV
which of the following would also indicate which interactions were in evidence:
1. electromagnet interaction
2. weak interaction
3. strong interaction
4. gravitational interaction
5. electroweak unification
6. Grand unification
7. superunification

It's about 9*10^12 eV. The temperature where electroweak symmetry breaking occurs happens at about 90 GeV, so at about 10^15 K.

3 x 10 2