In the Naked Scientists mailbox

14 May 2019

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Chris Smith and Katie Haylor opened up the Naked Scientists mailbag to see what listeners have been asking and telling us...

Katie - It turns out that our postman, as he was handing over the mail outside the office the other day, is a fan of the show, so thank you very much. Now he wants to know about gravity. What actually is gravity and what is it made out of? Ben, can you help us out with this one?

Ben - This is a great question. The answer essentially is that we don't know. Nobody really knows which is why it's a great question to be asking. We know there are four fundamental forces in nature and stay tuned to the back half of this program where you'll be hearing about them in a little more detail.

I’ll talk about two specifically; gravity is a force we're talking about here. This is something that exists between any two things that have mass, pulls them together. And we can compare that to another force that we sort of do know what it's made up of which is electromagnetism, this is the force that magnets feel when they attract each other. That force, if you want to say, is made up of something, it's actually made up of these particles called photons which are just little chunks of light. When magnets are attracting they're actually shooting little chunks of light back and forth at each other and that's what that force is made of, if you like.

If we were to bring in analogue to gravity, we don't know if there's something like that with gravity. Some people think there is, there think there might be a particle called the graviton, although this has never been detected. Other people would say there is no thing, it's actually just the physical bending of space-time itself that creates effects that like gravity. So short answer - we don't know. A lot of people are trying to find out - great question.

Katie - It's a big question isn't it?

Ben - Yeah.

Katie - But it sounds like the second half of this show may help us to try and understand some of this science.

Ben - Absolutely. A better understanding of dark matter will certainly lead to a better understanding of gravity.

Katie - So our postman actually picked a very good week to ask about gravity then?

Chris - And there you go. Thank you very much Ben for that first-class answer for our postman

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