Randall Munroe: Comics that ask “what if?”

Speaker

Randall Monroe – former engineer at NASA and most known for his webcomic at xkcd.com

Summary

Every week on his website xkcd.com, Randall writes a feature called ‘What If’ – where he answers questions using maths and displays them as an explanation interspersed with comics. For example, when asked what would happen when a baseball is thrown at the speed of light, he talks about the interactions with the air – superheating it to plasma and creating a mushroom cloud that would strike the batter. In his opinion, this would constitute a ‘hit by pitch’, and allow the batter to walk to first base (if it still existed).

Randall was asked how big Google’s data centres would be if all their data was stored on punch cards. Noone knows how much data Google holds, but Randall predicted it using estimates of the money Google has, or how many hard drives they use, or how big their data centres are, or how much electricity they used. He can use what he does know to improve the quality of guessing what he doesn’t. He predicted 10 exabytes of data, and perhaps another 5 exabytes of offline data stored in tape drives. A punch card holds about 80 characters, with about 2,000 cards in a box. 15 exabytes would cover the entire area of New England to a depth of 5km. A few weeks later he got a message from Google, consisting of punch cards. This is a puzzle, including a code, which gives them some equations, which Randall eventually cracks to get a message. The message was “No Comment”.

Randall enjoys maths, but not for it’s own sake. He likes using maths to take things he knows and then use them to discover what he could never know.

But sometimes maths cannot help. One of his user questions just contained the subject line “Urgent’ and the question “If people had wheels and could fly, how would we differentiate them from airplanes?”.

Allan Adams: The discovery that could rewrite physics

Speaker

Allan Adams: MIT Associate Professor with focus on Theoretical Physics.

(Illustrated by Randall Monroe, of http://www.xkcd.com fame, a former NASA employee who now writes a science-themed webcomic)

Summary

If you look at the sky you see stars, but if you look further and further you see nothing. Beyond that nothingness is the afterglow of the Big Bang. This afterglow is nearly completely uniform at 2.7 degrees, but has cooled slightly in small patches (20 ppm). These tiny discontinuities are caused by Quantum Mechanical ‘wiggles’ during the Big Bang, that have been stretched across the universe.

Before the Big Bang, our universe was extremely dense like a metal bell. On March 17 something new was discovered. Like a metal bell, this original universe could be ‘rung’ by quantum mechanics, then it could produce gravitational waves (like the sound from a bell). Nowadays these gravitational waves have faded, but early on the waves caused small twists in the structure of light that we see. By searching the sky from the South Pole, researchers recently discovered these wiggles in the light coming from distant stars.

What this implies is that our universe is in a ‘bubble’. It is then possible that our ‘bubble’ is just one of many, even though we may never see the others.

further reading here: http://www.space.com/25100-multiverse-cosmic-inflation-gravitational-waves.html . The big key here was that in the first fractions of a second, the universe was expanding faster than the speed of light, with our ‘uniform’ universe an expansion of a very tiny point in the original tiny dense mass. Gravitational waves were an important feature of this model, but could never be identified until recently. If our universe condensed around one region and expanded outwards, it is likely others did likewise, hence the ‘bubble’ analogy.