Blogs / Cosmic Variance

While surfing through the Guardian’s collection of the 20 best Hubble images, among many that I’ve seen and used before I came across this remarkable one that was completely new to me

Besides being quite stunning (and reminding me of one of the Star-Trek movies), I was struck by the caption, which reminded me that

A delicate ribbon of gas, the remnant of a supernova explosion more than 1,000 years ago. On or around 1 May AD 1006, observers from Africa to Europe and the Far East witnessed the arrival of light from what is now called SN 1006, the final death throes of a white dwarf star nearly 7,000 light-years away. The supernova was probably the brightest star ever seen by humans, surpassing Venus as the brightest object in the night time sky after the Moon. It was visible even during the day for weeks, and remained visible to the naked eye for at least two and a half years

It is wonderful that we have the partial accounts of astrophysical events from so long ago, but at best they constitute mostly qualitative descriptions that allow us to place some bounds on certain processes and hypothesize about what the event must have looked like back then. However, it did make me wonder what astronomy and astrophysics might be like a comparable or greater time in the future. Future astronomers will have at their disposal huge and detailed datasets, containing images and precision astrometry stretching over thousands of years. If we had had such technology when SN 1006 was first seen, we would have a complete record of its explosion, expansion, and cooling. In fact we’d have such records for a huge number of astrophysical events.

In the far future we might even hope for the same in cosmology – for example a completely new microwave sky to help us beat down cosmic variance. Of course that’s assuming we survive the death of the sun, asteroids, global warming and, of course, zombies. And if we’re that lucky, we’d better make the most of it. Because if cosmic acceleration is here to stay, distant objects will gradually move outside of our horizon, and our detailed astrophysics and cosmology observations, and images like the one above, will be all we’ll have to remind us of the rich and beautiful universe that used to surround us.