In this installment of These Vibes, Stevie speaks with Princeton University physics professors Steven Gubser and Frans Pretorius on their recently released Little Book of Black Holes (Princeton University Press, 2017). The discussion begins where the book ends, at the Epilogue, where the authors read their “Letter to Einstein.” From there we dive in to the definition and formation of black holes, and where they exist in our universe. Professors Gubser and Pretorius tell us about the experimental verification of these weird astrophysical things and answer listener questions like what would happen if a black hole entered our solar system? would we notice? Listen in and check out the book!
In the very beginning of the show, regular guest and science historian Ingrid Ockert joined us to review the stunning new documentary Jane (trailer), about the life and work of Jane Goodall, featuring much unseen footage from her younger years and research. For further reading she recommends Primates and Me, Jane.
In this episode of These Vibes, Stevie spoke with Dave Seal, a mission planner on the Cassini space probe which spent many years orbiting Saturn. Cassini operated its final maneuver, called the “Grand Finale,” and ended its observing by plunging in to Saturn just last Friday morning at 8am EST. It took a final image and took it’s last bits of data on Saturn’s atmosphere before being destroyed. Listen in to learn about the mission, its development, goals, and discoveries, and learn more about what it’s like to be a mission planner on a NASA space probe.
All that plus great music, and science news from microplastics in our seasalt to the new research on cancer cells.
Additionally, Brian and I chatted for a while (around 1.5 hours in) about the prospect of fusion rockets, and in particular developing them to shoot down apocalypse-inducing asteroids. Here’s a press release from NASA on developing fusion rockets.
Featured image is an artist’s conception of gravitational waves from a binary system. From LIGO.org.
Image with the recording is of the inside of the Tate Britain museum in London.
The main portion of this show is an interview with Dr. Lora Angelova – a chemist and researcher at the Tate Britain in London, England. What this means is, she uses chemistry, material sciences, physics, art history – and whatever else she needs – all towards the effort of conserving art. Currently, her research focuses on developing methods of surface cleaning artworks. Throughout our interview she takes us through some of the work involved to keep a piece of art in a state as close to its original as possible, and how much of an effort that takes. It’s truly a labor of love.
In the interview we discussed her work with NanoRestART, and micro-emulsions. Lora explained micelles, and that lead us to how soap works. Then we spoke a little on the surface of our cells – as it’s a similar concept.
After the interview, I spoke for a while about gravitational waves. Here’s approximately what I said on them:
If I were a betting woman, I’d say that you’re about to hear a lot in the news about these entities called “gravitational waves.” That is, if you keep up with science and tech news.
On Thursday, the LIGO experiment is having a press conference. BUT it’s been rumored for months that they might have seen something in their instrument. LIGO stands for Laser Interferometer Gravitational-wave Observatory. And what they search for is, you guessed it, gravitational waves.
From general relativity we know that gravity – the force that makes apples fall and keeps us here on Earth, and maintains the Earth orbiting the Sun – isn’t like the other forces. The other three forces: the electromagnetic, strong, and weak forces – all operate via particle interactions. So if two objects are attracted or repelled due to the electromagnetic force, this comes about because of particle exchange. But when two objects are gravitationally attracted to each other, this comes about due to the fact that massive objects actually warp the spacetime around them. Like when you sit on your bed with lots of stuff on it and everything falls in to you. Alternatively, think of a rubber sheet pulled taught with a bowling ball set on it. The bowling ball warps the sheet, causing any marbles
you throw on to the sheet to fall in to the ball. This is how gravity works.
And, in our sky, we can see gravity do this due to its effect on light. Light always takes the shortest path through spacetime, so if spacetime curves due to some massive object, then the light will curve. This effect creates these fascinating images on the sky called Einstein rings – these are absolutely gorgeous and dramatic and totally incredible. You can see one of these to the right of this page, but google for images. There’s many.
So what’s a gravitational wave? Well, if gravity is curvature of spacetime, then a gravitational wave is an oscillation in spacetime. Think of it like a stretching and compressing of a small bit of space – first vertically stretched and horizontally compressed, then horizontally stretched and vertically compressed, and again and again, back and forth – but that stretching and compressing action is traveling, at the speed of light, away from its source.
The LIGO instrument uses this property – and lasers – to try to measure gravitational waves. Essentially, they have VERY very precise lasers aimed across a distance, and if this light from the laser is stretched or compressed just a little tiny bit, then LIGO will pick it up. And if that stretching and compressing has the right signature, then it could be a gravitational wave.
A good next question is, where does the gravitational wave come from? What’s the source? Well, a gravitational wave is theorized to radiate out from just about any massive, moving source. So this could be, for example, two neutron stars spinning around each other at fantastic speeds, colliding black holes. Or you, driving in your car.
A key thing to note is that gravity is SO MUCH weaker than any of the other forces. This is why a magnet that you hold in your hand could attract a paperclip via the electromagnetic force, but could never really attract anything gravitationally. If you’re in to numbers, gravity is about 30 orders of magnitude – that’s a 10 with 30 zeros after it – weaker than the electromagnetic force.
And this is why LIGO is looking to observe gravitational waves from two neutron stars spinning around each other at fantastic speeds, but isn’t worried about picking up the waves from you driving in your car. And this is also why it’s so hard – and why it’s never been done before. But LIGO has been diligent…and there have been rumors of discovery for weeks now. So…watch this space.
And just so you know – gravitational waves have never been directly observed before, but
it’s on very very strong theoretical footing. First off, they come out of General Relativity, which has been tested time and time again. And second, they have been measured indirectly.
Here’s what we’ve seen. As a system – like binary neutron stars or black holes – radiate gravitational waves, they lose energy… this will cause the objects to spiral in towards each other and eventually collide. And this has been observed! Cue the Hulse-Taylor pulsar.
In the Hulse-Taylor system a…
…decrease of the orbital period [was observed] as the two stars spiral together. Although the measured shift is only 40 seconds over 30 years, it has been very accurately measured and agrees precisely with the predictions from Einstein’s theory of General Relativity. The observation is regarded as indirect proof of the existence of gravitational waves. Indeed, the Hulse-Tayor pulsar is deemed so significant that in 1993 its discoverers were awarded the Nobel prize for their work.
So, we are pretty sure they exist. And if we are able to observe gravitational waves directly from sources like black holes and dark matter, that would be totally revolutionary for astrophysics! It would show us the universe us in a whole, brand new way.
And with that, we’re all pretty pumped to hear what LIGO has to say on Thursday. And sometime soon I’ll try to get someone from the collaboration in here to talk about it.
Happy Christmas, listeners! In this rockin’ show Lucianne Walkowicz called in to WPRB from the Adler Planetarium in Chicago, where she works on NASA’s Kepler Mission as well as the Large Synoptic Survey Telescope (a telescope currently being built down in Chile). In this interview we focus on the Kepler mission’s search for exoplanets – these are planets outside of our solar system. We discuss questions such as: What makes a planet habitable? How does a star’s properties influence the planet’s habitability? How does Kepler go about finding these planets when they’re so much smaller and dimmer than their accompanying star? How could we know if there is life on these planets? And much more!