My article “Cosmology Q & A” has been published! It appeared in the magazine Australian Physics, 51 (2014) 42-6 and is reproduced here with permission. After a brief overview of modern cosmology, it (tries to) answer the following questions:
- Is space expanding, or are galaxies just moving away from us?
- Is everything getting bigger?
- Ordinary matter and radiation cause the expansion of the universe to decelerate. But our universe is accelerating! How? What is the universe made of?
- Dark Energy? Is that like Dark Matter?
- How big is the universe?
- How big is the universe really?
- If the universe were finite, could I see the back of my own head?
- Is space expanding faster than the speed of light?
- Are there galaxies moving away from us at more than the speed of light?
- Light from distant galaxies is observed to be redshifted. Is this because the expansion of space stretches the wavelength, or because is it a Doppler shift due to the recession of the galaxy?
- Does the universe have zero total energy?
- Energy is not conserved!? Shouldn’t that send shivers up the spine of any physicist?
- The very universe, we are told, began in thermal equilibrium. How did equilibrium establish itself so quickly?
- How does the initially smooth universe we see in the CMB become today’s universe of stars and galaxies?
As before, further questions in the comments are always welcome.