May 19, 2016

Janna Levin at AWF 2016: Gravitational Sensations

Looks like Gareth from Digital Services did well in his choice of AWF session -- and also in writing it up for us! Here's his definitely not-boring post:

Janna Levin's talk was a nice break from the usual panel discussions and one-on-one interviews that customarily fill up the schedule of a book festival. Instead she presented an audience-friendly lecture on modern physics - in particular the recent breakthrough recording of gravitational waves washing over the planet earth from the collision of two black holes in a distant galaxy.

Sound boring? Fortunately it wasn't, since Levin chose her metaphors wisely and had plenty of video clips to bring her monologue to life. Though you might have to excuse my ignorance as I breeze over the highlights of her talk (without much knowledge of physics to back me up!).

Levin spent the first half of the lecture just trying to open up the audience's mind to what gravity actually involves. Rather than being an all-powerful force that holds us to the ground, she asked us to imagine first that our natural state was weightlessness - it was actually the objects in our way (the ground beneath our feet) which stopped us drifting in one direction or another. To illustrate this point, she played a segment of an OK Go music video, which was filmed on an airplane in free-fall, allowing the band to move about in weightless suspension:

It was nice to have moments of levity like this, though her point was more subtle - she was gradually building a picture in our minds of Einstein's view of physics, which portrays gravity as curves in space-time that gradually pull on our otherwise weightless position. Hence, if you are in an airplane traveling at the same speed as this pull, you achieve the zero gravity as in the video above.

All this was a nice prelude to the actual subject of her talk - the scientific attempt to record the gravitational waves that hold us down - a subject covered in more detail in her book, Black Hole Blues and other Songs From Outer Space. It follows the path from Einstein's first theory of gravity through to the creation of one of the world's most sensitive scientific measurement instruments, which was created specifically to test one of the predictions of the theory. In particular, Einstein's theory suggested that a large enough cataclysm in the universe might cause a ripple big enough to "pluck" the gravitational curves that cross over our own planet.

In order to record such an event, scientists created LIGO - a four-kilometre long section of concrete pipe, with lasers running between tiny mirrors at each end, which would then be able to track a movement in the earth's gravitational field. In fact, there were two sister sites - each on opposite coasts of the US, so any instantaneous changes could be detected. The price tag? A cool US$620 million!

Fortunately they actually achieved their goal late last year and announced their finding in February of this year! You can hear their result in the following little clip - a fairly unassuming little sound for all the build up Levin had given it!

What is possibly more interesting to the lay reader is the personal stories of the scientists who made this discovery possible. The first idea for this experiment came in the fifties and it has taken decades of argument to convince the wider scientific field that such an experiment was useful or even likely.
Levin has the skill to interweave the science and the story of the scientists together in a way that is very approachable to a general audience and hence her talk made me very keen to check out one of her many books.

It was great to see that she also had quite some skills at handling left-field questions from the audience. In the midst of a run of serious questioners, one chap stood up and asked how it was that a beautiful woman such as herself decided to get into the unusual career of astrophysicist.

There were jeers from the audience, but Levin simply smiled and said that it was better that such ideas were brought out into the open, given that some members of our society do believe that a women's main goal is to be beautiful. In contrast, she said her parents were feminists and that she therefore didn't believe in such a goal from the outset. Her response was a final display of her sharp intelligence, which is able to cut through to the truth of the matter no matter how complicated or how banal!

-- Gareth

Ditulis Oleh : Auckland Libraries // 23:00


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