Jeremy Kasdin: The flower-shaped starshade that might help us detect Earth-like planets

Speaker

Jeremy Kasdin: Aerospace engineer at Princeton University.

Summary

In the next decade, Jeremy wants us to build a space telescope that can take pictures of Earth-like planets in distant galaxies. Astronomers now believe that every star in the galaxy has a planet, and up to a fifth might have an earth-like planet that can sustain life. The ‘pale blue dot’ picture of Earth is difficult to take from a long way away, because the nearby beaming star overwhelms the telescope making it impossible to see the planets. Jeremy’s colleagues are working on technology to block out the extreme light of the sun and instead focus on the planet.

One idea is similar to the concept of an eclipse – where a closer object blocks the star, reducing its interference to a ring or corona effect. This is similar to putting a hand over a spotlight so you can see more clearly. Translating it into space: we’d build a large portable screen, open it between a telescope and a star, then take a picture. However, the corona of a circular sunshade still obscures the planet. Instead the sun shade is designed with a flower like pattern, to control the diffraction of light and prevent it washing out the picture. This should allow clearer pictures to be taken of distant planets.

The star shade is as big as half a football field, and has to be flown 50,000 km away from the telescope and then held right in the shadow. His engineers have been designing the system for unfurling and moving the shade.

His hope is that once completed we can take pictures of the planets around nearby stars, then use the information to analyse them and investigate further. By building a giant flower-shaped star-shade and seeing other stars’ pale blue dot, our understanding of the world will change.

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.

Stephen Hawking: Questioning the universe

Speakers: Stephen Hawking – Physicist with University of Cambridge, known for the book “a brief history of time”. http://en.wikipedia.org/wiki/Stephen_Hawking

Summary

Until 1920s, people thought universe was static and unchanging. We then discovered that distant galaxies were moving away from us, which suggested originally everything was extremely close before expanding, hinting at a big bang. We have made progress understanding Maxwell’s equation and general relativity to understand how the universe has evolved, but struggled to describe the initial state of the universe. Under certain conditions, general relativity allows time to behave as another dimension, removing the distinction between time and space and allowing the universe to spontaneously create itself from nothing. We can use probability to simulate a number of different initial states which agree with observations. In this way, we have solved the creation of the universe.

Looking at extraterrestrial life, we believe life appeared spontaneously on Earth so it should be able to appear elsewhere. Algae fossils imply that life appeared on Earth within half a billion years of it becoming possible, which is short in the earth’s history. This implies that life can form relatively easily, but on the flipside we have not seen any aliens. From searches such as SETI, we can imply that there are no civilisations of our level of development within a few hundred light years.

Looking at the future, if we are the only intelligent beings in the galaxy we should ensure we survive and continue. But we are in a dangerous phase of history – our consumption of finite resources is increasing exponentially, as is our ability to change the world for good or evil. Our genetic code still carries selfish and aggressive instincts that may steer us astray. It will be difficult to deal with these problems to survive 100 years, not to mention thousands or millions. To ensure our survival beyond a hundred years we must expand into space. Stephen was later asked if he believes we are the only civilisation in the Milky Way at our intelligence level. He responds (after 7 minutes to compose the speech, edited out of the video) that he believes this is true, we would have found them otherwise. The other possibility is that our civilisation is in a late phase, and previous races of our technology level have not lasted long before destroying themselves.

Throughout his life, Hawking has tried to answer these 3 questions. He is grateful his disability has not prevented this, and it has given him more time to answer these questions.