My research interests are

>> cosmological thermodynamics – will the universe end in a heat death?
>> dark energy – theoretical problems with dark energy and observational constraints
>> general relativity – horizons, non-trivial energy conservation
>> anthropic selection effects

You can find out more about my work, and links to my publications, on my Cosmology page. I have also done some work in other scientific areas including physics-oriented software development and hydrology (and archeology!). This miscelaneous stuff goes on my Coding page. And from time to time, as time allows, I’ll spend some time on my blog.


Simple cosmology

The fantastic thing about cosmology is its ability to take questions previously considered the domain of philosophy and theology, and answer them on the grounds of observational evidence. Futhermore, it tends to be most successful when the questions are approached with complete disregard to legacy preconseptions. Do you have big questions? Visit your local cosmologist.

>> How old is the universe? – 13.7 billion years.
>> Is it static? – No, it is expanding and will probably continue to expand forever.
>> Are we at the center of the universe? – The universe has no unique center, just as the surface of a sphere has no unique locations.
>> Why are we here? – To increase the entropy of the universe.

The last two decades have seen cosmology grow from a speculative field, almost devoid of experimental support, into a precision science with firmly placed observational footholds. The level of agreement seen between the results of independent cosmological experiments is encouraging. The 3 most important experiments are undoubtedly:

Temperature anisotropies in the cosmic microwave background

The leftover afterglow of the big bang still radiates in the vacuum between the stars. At just 3 degrees kelvin, it is too dim and cold to be seen with the human eye, but radio antennas can recieve it (in fact it is partly responsible for the snow on an un-tuned tv). This radiation, the ‘CMB’, is not exactly the same temperature in all directions. It is slightly cooler in directions where the early universe was more dense than average, and slightly warmer in directions where the early universe was less dense than average.

The distance between hot and cold spots in the CMB depends on the characteristic distance between overdense and underdense regions in the early universe, and on way the universe’s geometry lenses the light en-route to Earth. Thus by measuring the distribution of hot and cold spots in the CMB, we can determine the geometry of the universe.

The result: the universe is approximately flat on large-scales.

search for Chas A. Egan on NASA ADS