Navigating the Cosmic Questions: Gravity Assists, Neutrinos, and Time Dilation Explained

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Professor Fred Watson: Hi there.

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Andrew Dunkley: Thanks for joining us. This is Space Nuts, a

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Q and A edition, and we've got a bunch of

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questions to get through. Uh, Larry wants to

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know about orbital velocity and his question

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is quite timely because he brings up the

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BepiColombo mission. And we have an update

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on that. Uh, Eduardo is

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asking us about neutrinos. In fact, these

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last three questions dovetail into each

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other. So Eduardo about neutrinos. Uh,

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Shumo is asking about interstellar beacons

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that might be powered by neutrinos.

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And, uh, Colin is asking about time

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dilation. So plenty to talk about on this Q

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and A edition of Space nuts. Stick

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around.

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Professor Fred Watson: 15 seconds. Guidance is internal.

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10, 9.

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Ignition sequence start.

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Professor Fred Watson: Space nuts.

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Professor Fred Watson: 5, 4, 3. 2. 1, 2, 3, 4,

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5, 5, 4, 3, 2, 1.

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Andrew Dunkley: Space nuts.

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Professor Fred Watson: Astronauts report it feels good.

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Andrew Dunkley: And he's back again to, uh, solve all those

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riddles for us. It's Professor Fred Watson

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Watson, astronomer at large. Hello, Fre.

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Professor Fred Watson: How are you doing, Andrew?

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Andrew Dunkley: I'm doing well. You looking rather, um,

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um.

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Professor Fred Watson: Cold.

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Andrew Dunkley: Yes. Maybe. Yeah, we had

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a really good warm spell there for a while

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and then it just petered out and we're back

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to some quite chilly weather. By

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the time this podcast comes out, it could be

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back to warm again. It's

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that time of year where we've got the tug of

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war between winter trying to hang on and

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spring trying to take over. And so,

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uh, you get a little warm snap and then it's

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cold again and then you another warm snap and

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then one day it just stays warm and then it

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gets hot, hot, hot. And then the opposite

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happens going into autumn or fall or

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whatever, wherever you're from. And however

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you say it. But, um, yeah, right now we're

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into spring, uh, very windy

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weather this time of year out our way.

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Nothing to do with actual wind. It's just so

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many people sneezing. You just, you know,

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volatile environment.

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Professor Fred Watson: Yeah.

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Professor Fred Watson: Ah, did you, um, you were going to try and

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get some shots of, uh, pollen?

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Andrew Dunkley: I did try and so far I've failed.

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Professor Fred Watson: Okay.

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Andrew Dunkley: I haven't been, uh, but see, last time I got

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the pollen, uh, corona photo, I was

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using an older model phone and I've got

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a feeling that the new phone

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compensates and actually stops me from

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getting the shot.

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Professor Fred Watson: Yeah.

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Andrew Dunkley: Ah, but I'll give it another try. Uh, I might

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have been too early. Cause the best time is

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mid afternoon, isn't it?

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Professor Fred Watson: Probably, yeah. Uh, you should be able to see

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it with the naked eye and that should tell

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you what your, um, phone is likely

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to pick up.

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Andrew Dunkley: A good friend of mine once told me, though,

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never to look at the sun.

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Professor Fred Watson: Uh, indeed, I tell people that all the time.

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But that's why what you do is you get the sun

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behind a wall or a building or something,

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just enough that you can see the immediate

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sky around it and that's where you might see

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these colour bands. And just in case any of

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our listeners wonder what we're talking

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about, um, pollen, uh,

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particles in the atmosphere. Because there

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are many, many millions of them and they're

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all of a uniform size, they have an effect on

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light called diffraction, uh, and that

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you can get coloured rings around the sun

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caused by the diffracting effect of these

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pollen, uh, uh, particles. And that's

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what Andrew's looked for. I've seen them in

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Coonabarabran on occasion when I used to live

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out there. We tend not to see them in Sydney

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because the air is probably not

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Andrew Dunkley: clear enough because there's more pollution

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in

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Professor Fred Watson: the air than pollens. Yes, there is. Pollen

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pollination.

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Andrew Dunkley: Yeah, yeah. It's quite

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spectacular though. Yes, I think

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we talked about it on an episode and I said,

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okay, um, challenge acceptance, and went

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outside, took one photo and got it.

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Professor Fred Watson: Yes, yes, that's right.

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Andrew Dunkley: Proving more difficult this time. Let's get

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into our questions.

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Uh, this first one comes from Larry.

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Professor Fred Watson: Hello, Fred Watson and Andrew.

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This is Larry from, um, York,

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Nebraska, that is.

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I've been listening to your podcast

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almost continually for months.

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Heard an old edition

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talking about

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Speaker D: using,

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Professor Fred Watson: uh, the gravitational boost

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around planets,

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particularly Pepe

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Colombo. Fred Watson

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said that, uh, had to

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use, uh, nine booths to get

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the BP Columbo spacecraft to

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speed up to the speed of

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Mercury. However, from

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previous podcasts it seems

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the more you speed up the orbital

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velocity, the further away from the

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sun you get. So don't you have to

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use the

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gravitational wells to slow down

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to get to Mercury? Because Mercury's

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orbital velocity should be a whole lot less

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than Earth's. Thank you.

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Andrew Dunkley: Thank you, Larry. And, uh, hope all is well

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in wonderful Nebraska. Um,

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yeah, he brings up an interesting point. Uh,

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maybe we can discuss that after we break the

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news about BepiColombo. The

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BepiColombo mission to Mercury. And

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we did talk about how it had to do,

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um, quite a bit of manoeuvring, um, to,

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to achieve the velocity it required. You

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might remind us about that, Fred Watson, and

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then tell us, um, what's happening now.

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Professor Fred Watson: Uh, yes, so, uh, BepiColombo,

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a joint, um, ESA,

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uh, JAXA mission, I think. Japanese

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Aerospace Exploration Agency.

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Um, eight years it's been on

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its way so far and ah,

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there have been nine, I think I'm right, nine

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gravity assists, one of Earth, two of

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Venus and six of Mercury itself.

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Uh, and the reason why it's in the news at

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the moment is because um, the

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spacecraft has separated

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from its um, something called

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the MTM M M which

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is the uh,

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Mercury Transfer Module. In other

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words it's almost like a service module

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that's been uh, attached to the spacecraft.

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It's got solar panels, it's got you know,

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various uh, um, uh,

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feeds uh, on board for

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the requisites of the spacecraft itself

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that has now basically been jettisoned.

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Uh, and so BepiColombo is on its

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own as it spirals

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down towards the planet

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Mercury to eventually go into orbit

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around Mercury.

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Andrew Dunkley: And seeing they've now separated, uh, the

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lawyers will be deciding who gets what

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Professor Fred Watson: assets, who gets what. Yeah,

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indeed, that's right. Um, but let's just

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go to um, Larry's question. Uh,

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Larry's. You're

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absolutely right. This is something

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I think it does all our heads in that

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ah, if you've got a spacecraft in orbit

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around something and you speed it up,

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what happens is it goes to a higher orbit but

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it slows down that um,

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speed the bottom line. And the

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reverse is true with BepiColombo

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going to Mercury. So um,

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remembering that the Earth's orbital velocity

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around the sun

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is 30 kilometres per second,

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uh Mercury has an orbital

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velocity which is in the

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region of 50 kilometres per second.

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M uh because it's nearer the sun it

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needs a higher velocity to stop it from

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falling into the so 50

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kilometres per second is its speed. So in

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that respect BepiColombo

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is catching up uh in terms of

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speed uh with Mercury.

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But to do that you slow it

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down, you have to shed the Earth's

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uh, orbital velocity to push the

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spacecraft in towards the sun which

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speeds it up uh, so that it would be

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travelling faster than the Earth. If I can

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put it that way. It's all about the balance

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between gravity and velocity.

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Uh, I'm probably not making this sound very

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clear but the bottom line is that it's taken

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those uh, nine gravity assists to get

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from 30 kilometres per second going around

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the Earth to roughly 50

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kilometres per second average speed of

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Mercury. I think it gets significantly higher

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and lower because Mercury's got quite an

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elliptical orbit. Um, believe Its maximum

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is 59 kilometres per second when it's closest

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to the sun. So you're talking about a

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significant increase in velocity which

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achieved by slowing the spacecraft down so it

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falls in towards the Inner solar system. Does

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that make sense?

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Andrew Dunkley: Yeah, I think we talked about, uh, when this

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first came up, we talked about how much more

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difficult it is to go towards the

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centre of our solar system than it is to go

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Professor Fred Watson: outwards in that regard. It is, that's

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correct, yes.

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Professor Fred Watson: Yeah.

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Andrew Dunkley: So there's a lot of mathematicians, um,

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at work trying to figure this one out.

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Um, um, you know, taking into account

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orbital mechanics, M and the, uh,

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everything that goes into it, uh, it's quite

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an amazing feat, to be honest, to uh, to

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come up with this. And yet you think a jump

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of only 20 kilometres per second, 30 to 50,

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wouldn't. It doesn't sound all that

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difficult. But when you look at what they've

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actually had to do to achieve it.

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Professor Fred Watson: That's right.

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Andrew Dunkley: Quite extraordinary.

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Professor Fred Watson: It is, it's, it's, it is a significant amount

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when you think about it. You know, you're

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like that 20 kilometres per second, uh,

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is, it's. I think it was about the

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same orbital speed that, um, New Horizons

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was launched at when it was one of the

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fastest spacecraft ever launched. I think it

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was 23 kilometres per second it had. So

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it's a not insignificant jump in velocity.

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Andrew Dunkley: It just takes a lot of manoeuvring to make it

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happen.

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Professor Fred Watson: Indeed, yeah, that's right.

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Andrew Dunkley: There you go. Larry explained and still, um,

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scratching my head.

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Thanks for the question. Um, this is Space

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Nuts with Andrew Dunkley and Professor

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Fred Watson Watson. It's a Q and A edition.

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Professor Fred Watson: I believe that this nation should commit

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Andrew Dunkley: itself to achieving the goal,

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before this

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Professor Fred Watson: decade is out, of landing a man

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Professor Fred Watson: on the moon and returning him safely to the

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Earth.

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Andrew Dunkley: These nuts. Now, next question comes from

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Eduardo. I hope I'm pronouncing that

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correctly. Um, he says, given

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that neutrinos are the second most abundant

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subatopic particle, just after photons.

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Uh, but contrary to photons, they don't seem,

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seem to interact that much with matter. Do

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black holes swallow neutrinos

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or do they just pass through them? Are

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neutrinos affected by gravity at all?

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Professor Fred Watson: Um, so yes, they are. Uh, and

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I mean in the, you know, light is as. Well,

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of course, light, that's the thing about a

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black hole, um, uh, won't even

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allow the release of light beyond the event

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horizon. Uh, and the same is true

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with neutrinos. So neutrinos,

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they can't pass through a black hole. Uh, if

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they cross the event horizon, they're

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trapped, uh, just like particles of

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light. Uh, um,

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uh, it is a bit weird with

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neutrinos because they Exactly. Um, as

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Eduardo says, they pass through normal matter

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very easily. They don't interact much with

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normal matter. Uh, but nevertheless

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gravity and the curvature of space time,

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which is really what we're talking about with

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a black. Black hole, uh, they affect them

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just the same as everything else.

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Speaker D: Hmm.

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Andrew Dunkley: Simple as that. It wouldn't be too much. That

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would not be affected by gravity.

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Professor Fred Watson: Yes, that's right. Uh, we think dark

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matter is too. Well, we know dark matter is.

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That's the only way we know it exists. So.

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Andrew Dunkley: Yes, well, it seems to clump in higher

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gravitational fields, doesn't it?

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Professor Fred Watson: That's correct, yes.

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Andrew Dunkley: Um, even though we don't really understand

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it, although we do think they may have

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identified it recently. Uh, I think we talked

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about that last episode. So, um,

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yeah, we're slowly chipping away at the

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mystery of dark matter, hopefully. So

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he said that, um, neutrinos are the second

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most abundant subatopic particle. Is that

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right?

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Professor Fred Watson: Um, I'd need to cheque that, but I think it's

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probably right. Yes. Uh,

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I think that's ah, a correct statement.

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Andrew Dunkley: Do we know what they're supposed to do?

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What's their function?

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Professor Fred Watson: Well, yeah, they're um, byproduct

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of, uh, nuclear reactions.

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And they are prolific, as

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Eduardo suggested. So, um,

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with um, for example, the nuclear reactions

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that power the sun, uh, the

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um, what's it called, the fusion

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reactions, uh, it's got a name.

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Proton. Proton reaction. There's several

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different ones anyway. They not only

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produce, uh, helium from hydrogen,

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uh, but the energy that they produce, uh, is

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in gamma rays and in neutrinos as well.

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Professor Fred Watson: There you, um, go.

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Andrew Dunkley: Fascinating.

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Um, Eduardo, that's um, about all we can tell

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you about that, but thanks for the question.

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Lovely to hear from you. We're whipping m

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through them, Fred Watson. We are.

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Uh, this is Space Nuts, a Q and A edition

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with Andrew Nunkley and Professor Fred Watson

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Watson.

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Professor Fred Watson: Three, two, one.

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Andrew Dunkley: Space Nuts. Uh, our next question

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comes from Shumo, who says. Hi, Fred Watson

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and Andrew. Another alien communication

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question. SETI understandably concentrates on

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radio and optical signals, but are we being

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too anthropo. I can't

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say it. Anthropocentric

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about the carrier. Couldn't, uh, advanced

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civilization use high energy gamma rays or

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even neutrinos as an interstellar beacon,

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encoding information in the timing or energy

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of individual event. Example, repeated gamma

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ray or neutrino events from the same point

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in the sky following the prime numbers would

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be very difficult to explain. Naturally,

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given that, uh, uh, we

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already have gamma ray and neutrino

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observatories watching the sky. Has anyone

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systematically searched their data for

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mathematically structured patterns that might

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be artificial? That comes from Shumo in

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Oxford in the uk. That's a really good

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question. Like that's out of the box. Isn't.

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Professor Fred Watson: Um, is a good question. And

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in a way, um, the answer lies in

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the fact that uh, when gamma ray bursts

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were first detected, uh, which you'll

368
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remember were detected by spacecraft

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satellites that had been launched

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specifically to look for evidence of breaches

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of the Nuclear Test Ban Treaty, the

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Atmospheric Nuclear Test Ban Treaty. That's

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what they were built for. They didn't see any

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nuclear tests, but uh, they

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saw these things coming from the sky, uh,

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bursts of radiation. So the first thing you

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think of when you see something like that is,

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is this a SETI signal,

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uh, or something artificial now,

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um, with gamma rays and indeed neutrino,

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uh, radiation. I guess

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you would tend to put that,

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to put an artificial origin fairly

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low on the list of, of candidate,

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um, reasons why these things are flying

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through space. Because they're very, very

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high, energetic, high energy, um,

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carriers. Uh, we're talking about a high

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energy universe here. Having um,

390
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said that, I recently wrote the

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foreword for a book by a group of

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colleagues at the Western Sydney University,

393
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which is called High Energy

394
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Astrobiology. Uh, and there you

395
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have it. The link between high energy

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physics phenomena and the science

397
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of the origin and evolution of life.

398
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Uh, and so I can't remember actually the

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details of the chapters. Um, uh, I

400
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do have a copy of the book which I looked

401
00:16:43.800 --> 00:16:45.950
through and enjoyed reading. Um,

402
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but uh, I can't remember the details. But

403
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um, I wouldn't mind betting that somewhere in

404
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there somebody is basically

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highlighting essentially the same question

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that Schumach has raised here.

407
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So.

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Andrew Dunkley: Yeah, I imagine so. But

409
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surely there'd be easier ways to send a

410
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message if you were.

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Professor Fred Watson: Yeah.

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Professor Fred Watson: Uh, rather than blowing up a planet or

413
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something like that, which is, you know, the

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kind of energies that we're talking about

415
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here. Yes.

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Andrew Dunkley: No, it kind of worked for. Ah, the Empire

417
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didn't.

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Professor Fred Watson: Depends on whose side you're on really.

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Andrew Dunkley: Yes, but,

420
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um. Would lasers be feasible over, um,

421
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parsecs?

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Professor Fred Watson: Yeah, they are. I mean, and so. Yes. But you

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know, in that regard I, uh, guess, um.

424
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Uh, you know, Shuma's already raised

425
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the issue that um, we've got,

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uh, the idea of optical communications

427
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as part and parcel of our

428
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retinue of researchers,

429
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uh, when it comes to possible

430
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SETI signals. Um,

431
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and exactly as

432
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Schumacher says, uh, SETI understandably

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concentrates on radio and optical signals.

434
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And yeah, that's why, because they're going

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to be the easiest to produce. Very much so.

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Optical signals I think have been neglected a

437
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bit in comparison with radio signals.

438
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But that is coming to an end because,

439
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uh, the latest instruments

440
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that we have, looking at the optical sky,

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optical and near infrared sky, and I'm

442
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thinking particularly of the Vera C. Rubin

443
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Observatory. Now it finds transient

444
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events, uh, millions per

445
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night. By transient events, I mean things

446
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that come and go in the dark. And of course

447
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communication signals would fall into that

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category.

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Speaker D: Yeah.

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Andrew Dunkley: When I was doing the research for my

451
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new sci fi trilogy, um,

452
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the first book in the series is called the

453
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Signal. And I did

454
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quite um, a bit of research on what

455
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signal would be likely to be received

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on Earth by an alien intelligence.

457
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And it basically came down to the signals

458
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we use every day on our own planet. The

459
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signals in the hydrogen line,

460
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1.4 to, to 1.66

461
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gigahertz, um, 14, 20 megahertz

462
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range that AM radio

463
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frequencies basically, um, more or less. Uh,

464
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so that's what I based it on.

465
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Um, but

466
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that's more likely to be the kind of

467
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signal that would be sent by a communicative

468
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intelligence beyond Earth. And

469
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that's where the Drake equation comes in.

470
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Um, I think they're based on an

471
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intelligence that is capable of

472
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communication.

473
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Professor Fred Watson: And you're absolutely right.

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Right from the beginning of what you might

475
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call the SETI era, looking for

476
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extraterrestrial intelligence. That

477
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hydrogen line that you've spoken of, 21

478
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centimetre line, to put it in wavelengths

479
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rather than frequency, um,

480
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is what cold hydrogen emits.

481
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So it's the most prolific

482
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Professor Fred Watson: spectral uh,

483
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Professor Fred Watson: line in the whole universe

484
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of any uh, frequency band.

485
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And so um, it is naturally where you would

486
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start thinking about broadcasting if you are

487
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trying to send a signal out, uh, to

488
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another intelligence, which

489
00:20:28.820 --> 00:20:31.200
that's a whole, I guess the whole um,

490
00:20:32.160 --> 00:20:34.880
proposition of SETI that uh, the

491
00:20:35.120 --> 00:20:37.240
intelligent species out there might want to

492
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communicate. And how they're going to do it.

493
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Well, they're going to use the spectral line

494
00:20:41.760 --> 00:20:43.800
that we're looking for anyway because that's

495
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something we're using to m. Map the universe.

496
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Speaker D: Yeah.

497
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Andrew Dunkley: Was the wow. Signal in that frequency range?

498
00:20:48.600 --> 00:20:50.720
Professor Fred Watson: I think I, uh, think it was, yes. Yeah, I

499
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think it was.

500
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Andrew Dunkley: And that, that came from the um,

501
00:20:54.720 --> 00:20:57.680
Sagittarius constellation region of

502
00:20:57.680 --> 00:21:00.560
spaces. Because I researched that as well

503
00:21:01.280 --> 00:21:04.180
off the top of my head. Um, they

504
00:21:04.180 --> 00:21:06.100
have actually studied that part of the

505
00:21:06.100 --> 00:21:08.980
universe and they at this moment cannot find

506
00:21:08.980 --> 00:21:11.730
anything to suggest that it was an artificial

507
00:21:11.730 --> 00:21:14.140
uh, signal. But

508
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they still haven't figured that one out, have

509
00:21:16.220 --> 00:21:16.540
they?

510
00:21:16.780 --> 00:21:19.110
Professor Fred Watson: No, there have been a few ideas like radio,

511
00:21:19.110 --> 00:21:21.570
uh, emission from comets. That was one. Uh.

512
00:21:21.570 --> 00:21:23.260
Cause I think there were comets in the sky at

513
00:21:23.260 --> 00:21:25.740
the time. But yeah,

514
00:21:26.780 --> 00:21:28.140
it's still an open question.

515
00:21:29.340 --> 00:21:32.260
Andrew Dunkley: Yeah, I guess so. All right, um, that's

516
00:21:32.260 --> 00:21:34.700
a great question. Thanks uh, Shumo, for

517
00:21:34.700 --> 00:21:37.360
sending it in. Um, but uh, yeah, there's

518
00:21:37.360 --> 00:21:40.120
probably easier ways to do things and uh, if

519
00:21:40.120 --> 00:21:42.280
you're going to send a signal to an

520
00:21:42.680 --> 00:21:45.000
alien civilization, you probably want them to

521
00:21:45.000 --> 00:21:48.000
be able to figure it out rather

522
00:21:48.000 --> 00:21:50.600
than send them something complex and they go,

523
00:21:50.600 --> 00:21:53.520
no, no, I don't know what that was. Um, let's

524
00:21:53.520 --> 00:21:56.120
go to our final question from Colin.

525
00:21:56.680 --> 00:21:58.040
Speaker D: Hello, Andrew and Fred Watson.

526
00:21:58.040 --> 00:22:00.960
Colin from Adelaide. I love the

527
00:22:00.960 --> 00:22:03.440
science fiction movie project Hail Mary,

528
00:22:03.910 --> 00:22:06.790
which I've seen twice. But I'm still quite

529
00:22:06.790 --> 00:22:09.230
confused about the time dilation effects. In

530
00:22:09.230 --> 00:22:11.950
the movie. RYLAND Grace travels

531
00:22:11.950 --> 00:22:14.710
12 light years to his destination

532
00:22:15.190 --> 00:22:18.070
at ah, Tau Ceti in four years

533
00:22:18.070 --> 00:22:20.710
and eight months. How can this be? The

534
00:22:20.710 --> 00:22:23.670
Beatles powered by the astrophage

535
00:22:23.910 --> 00:22:26.550
fuel carrying Tau Moeba, the

536
00:22:26.550 --> 00:22:29.350
solution to the astrophage problem with

537
00:22:29.350 --> 00:22:32.310
the sun reach Earth even quicker than.

538
00:22:32.900 --> 00:22:35.860
Than this. How can that be? And lastly,

539
00:22:35.860 --> 00:22:38.500
if Ryan Grace had returned

540
00:22:38.740 --> 00:22:41.580
to Earth, how much younger would he be

541
00:22:41.580 --> 00:22:44.500
than those he left behind? Very confusing.

542
00:22:44.500 --> 00:22:46.700
I hope you can help. Thank you. Love the

543
00:22:46.700 --> 00:22:47.300
podcast.

544
00:22:48.980 --> 00:22:51.820
Andrew Dunkley: Yeah, thanks, Colin. Um, I've seen the movie

545
00:22:51.820 --> 00:22:53.980
a couple of times myself and I've got to

546
00:22:53.980 --> 00:22:56.420
confess that I'm as confused as Colin

547
00:22:56.740 --> 00:22:59.300
in regard to the distances travelled and how

548
00:22:59.300 --> 00:23:02.300
fast they achieved it. Even though they came

549
00:23:02.300 --> 00:23:05.190
up with a new drive concept that

550
00:23:05.220 --> 00:23:08.070
um, even that I had trouble getting

551
00:23:08.070 --> 00:23:10.270
my head around, they, they did explain it and

552
00:23:10.270 --> 00:23:13.110
I just sat there sort of glazed look on

553
00:23:13.110 --> 00:23:16.110
my, on my face. Um, because it

554
00:23:16.110 --> 00:23:18.870
was uh, it was very cleverly done.

555
00:23:19.110 --> 00:23:21.990
But I don't know how they did it.

556
00:23:22.630 --> 00:23:25.230
Someone else might be able to explain uh, it

557
00:23:25.230 --> 00:23:28.070
to me. Um, I suppose we

558
00:23:28.070 --> 00:23:31.070
can tackle the question in two ways. My

559
00:23:31.070 --> 00:23:33.550
answer, Colin, is it's science fiction. You

560
00:23:33.550 --> 00:23:36.000
can do whatever you damn would like. Um,

561
00:23:36.520 --> 00:23:38.760
but that's just, that's the, that's a very

562
00:23:38.760 --> 00:23:41.720
simplistic answer. Um, when I

563
00:23:41.880 --> 00:23:44.880
write my science fiction novels, I

564
00:23:44.880 --> 00:23:47.640
want at least some of it to be as

565
00:23:47.640 --> 00:23:50.480
believable as possible. And so

566
00:23:50.480 --> 00:23:52.320
I'm, I'm in your boat. I want to know how

567
00:23:52.320 --> 00:23:55.200
they did it. Um, the

568
00:23:55.200 --> 00:23:56.840
other, yeah, the other side of it is,

569
00:23:57.170 --> 00:24:00.120
um, that we should

570
00:24:00.120 --> 00:24:02.390
explain time dilation and

571
00:24:03.590 --> 00:24:05.550
see where that falls within the parameters of

572
00:24:05.550 --> 00:24:08.030
the film. You haven't seen it, Fred Watson,

573
00:24:08.030 --> 00:24:10.390
have you? Oh, you have? What did you Think.

574
00:24:10.670 --> 00:24:12.910
Professor Fred Watson: Um, so, uh. Well, I was hoping you'd have the

575
00:24:12.910 --> 00:24:15.590
answer to this question. Not like, because I

576
00:24:15.590 --> 00:24:18.470
did watch it. I watched it on a flight from,

577
00:24:19.670 --> 00:24:22.630
a flight from Sydney to Paris,

578
00:24:23.570 --> 00:24:26.350
um, which uh, gave

579
00:24:26.350 --> 00:24:29.200
me enough time to watch the movie uh,

580
00:24:30.110 --> 00:24:32.270
thoroughly but still,

581
00:24:33.150 --> 00:24:35.310
I was still vaguely half asleep at the time.

582
00:24:35.630 --> 00:24:38.350
So um, and look, so I can't,

583
00:24:38.830 --> 00:24:41.730
I'm, I can't comment on those um, those uh,

584
00:24:41.950 --> 00:24:44.910
values uh, that um, that uh, Colin's

585
00:24:44.910 --> 00:24:45.510
given us. But.

586
00:24:45.510 --> 00:24:47.590
Andrew Dunkley: Well I, I got it. I've just done a quick

587
00:24:47.590 --> 00:24:50.510
search and. Okay, so the, the destination

588
00:24:50.750 --> 00:24:53.270
for our hero of the movie uh,

589
00:24:53.470 --> 00:24:56.350
was the star system Tau Ceti which was,

590
00:24:56.510 --> 00:24:59.200
is 11.9 light years from

591
00:24:59.200 --> 00:25:01.440
Earth. To get there.

592
00:25:02.080 --> 00:25:04.800
Um, the spacecraft was

593
00:25:04.960 --> 00:25:07.560
powered by a microorganism called

594
00:25:07.560 --> 00:25:10.560
Astrophage that converts mass into pure

595
00:25:10.560 --> 00:25:13.520
energy and that enabled

596
00:25:13.760 --> 00:25:15.720
the constant acceleration of

597
00:25:15.720 --> 00:25:18.600
1.5 g for the first half of the trip

598
00:25:18.600 --> 00:25:21.280
and then it flips and decelerates at 1.5 g

599
00:25:21.280 --> 00:25:23.440
for the second half of the trip. Its peak

600
00:25:23.440 --> 00:25:25.890
velocity was roughly

601
00:25:25.890 --> 00:25:28.490
92% the speed of light. Okay.

602
00:25:29.690 --> 00:25:31.690
If that's the case, travelling

603
00:25:31.930 --> 00:25:34.570
11.9 light years would take

604
00:25:34.810 --> 00:25:37.650
longer than 11.9 years and

605
00:25:37.650 --> 00:25:40.410
he got there in, I think it was

606
00:25:40.410 --> 00:25:43.250
four years. Uh, uh, that's why

607
00:25:43.250 --> 00:25:44.330
Colin's confused.

608
00:25:44.650 --> 00:25:47.290
Professor Fred Watson: Well, I mean time dilation only works.

609
00:25:47.290 --> 00:25:47.770
Andrew Dunkley: Yes.

610
00:25:48.970 --> 00:25:51.410
Professor Fred Watson: When you're talking about two separate frames

611
00:25:51.410 --> 00:25:52.090
of reference.

612
00:25:52.330 --> 00:25:55.250
Andrew Dunkley: Well, it's 11.9 light years if

613
00:25:55.250 --> 00:25:56.250
you're staying on Earth.

614
00:25:56.490 --> 00:25:56.970
Professor Fred Watson: Yes.

615
00:25:57.930 --> 00:25:59.290
Andrew Dunkley: When you're travelling it's a different

616
00:25:59.290 --> 00:26:00.010
kettle of fish.

617
00:26:00.170 --> 00:26:03.130
Professor Fred Watson: Yes, that's correct. Um, and so the

618
00:26:03.770 --> 00:26:06.609
time dilation, the time basically

619
00:26:06.609 --> 00:26:09.450
slows down for you as you're travelling

620
00:26:09.770 --> 00:26:12.250
relative to the person back on Earth.

621
00:26:12.890 --> 00:26:15.530
Uh, and so that seems to make sense from

622
00:26:15.930 --> 00:26:18.490
what you were saying that um, the experience

623
00:26:19.050 --> 00:26:21.880
of the astronaut is one

624
00:26:22.040 --> 00:26:24.720
of, in terms of Earth, time is a

625
00:26:24.720 --> 00:26:26.600
shorter time even though as far as the clocks

626
00:26:26.600 --> 00:26:28.120
are concerned they're still ticking at the

627
00:26:28.120 --> 00:26:30.120
same speed for the person who's travelling.

628
00:26:30.200 --> 00:26:33.200
Andrew Dunkley: Yeah. And I uh, must confess that

629
00:26:33.200 --> 00:26:35.800
in doing my research for the book that's

630
00:26:35.970 --> 00:26:38.880
um, the target star that

631
00:26:38.880 --> 00:26:41.560
shall remain nameless in my storey. Otherwise

632
00:26:41.560 --> 00:26:43.640
it gets too predictable.

633
00:26:44.430 --> 00:26:44.600
Professor Fred Watson: Um,

634
00:26:47.080 --> 00:26:49.160
Andrew Dunkley: was a certain distance from Earth

635
00:26:50.590 --> 00:26:53.230
as the crow flies or as the photons

636
00:26:53.230 --> 00:26:56.190
fly, but in travelling there

637
00:26:56.590 --> 00:26:59.310
in a, in a capable vessel,

638
00:26:59.750 --> 00:27:02.670
um, the, the time to get

639
00:27:02.670 --> 00:27:05.150
there was cut. Right. Quite dramatically

640
00:27:05.630 --> 00:27:08.430
but in doing so you didn't age,

641
00:27:08.430 --> 00:27:11.310
but everybody back on Earth did still age

642
00:27:11.470 --> 00:27:14.100
the so many light years. Uh,

643
00:27:14.190 --> 00:27:16.110
and, and that's the quandary, isn't it?

644
00:27:16.110 --> 00:27:16.750
Professor Fred Watson: It's um.

645
00:27:17.150 --> 00:27:19.390
Professor Fred Watson: Well, yes, the Twins paradox, basically.

646
00:27:19.550 --> 00:27:20.190
Andrew Dunkley: Exactly.

647
00:27:20.190 --> 00:27:21.020
Speaker D: Yeah. Yeah.

648
00:27:21.660 --> 00:27:24.620
Andrew Dunkley: So, um, it is a thing and it.

649
00:27:25.340 --> 00:27:28.330
Yeah, the. The traveller doesn't,

650
00:27:28.330 --> 00:27:30.620
um, take that amount of time to get there

651
00:27:30.620 --> 00:27:33.180
because of the fact that they're

652
00:27:33.420 --> 00:27:35.900
moving through space at a. At a high

653
00:27:35.900 --> 00:27:37.640
velocity. And, um.

654
00:27:39.660 --> 00:27:42.340
Yeah, I really

655
00:27:42.340 --> 00:27:43.900
struggle to explain this stuff.

656
00:27:44.300 --> 00:27:46.900
Professor Fred Watson: Well, you should. Yeah. The calculation's

657
00:27:46.900 --> 00:27:49.830
easy. Uh, for time dilation, I've seen

658
00:27:49.830 --> 00:27:52.790
it. 1 over the square root of 1 minus

659
00:27:52.790 --> 00:27:54.630
V squared over C squared. You could do that

660
00:27:54.630 --> 00:27:55.670
in your head, Andrew.

661
00:27:55.670 --> 00:27:57.710
Andrew Dunkley: Yeah, I actually had it written down.

662
00:27:58.590 --> 00:28:01.350
I did have it written down. Yeah. That's the

663
00:28:01.350 --> 00:28:03.870
one. Um, but, yeah, I don't have to.

664
00:28:04.430 --> 00:28:06.710
Professor Fred Watson: Nearly everything in special relativity has

665
00:28:06.710 --> 00:28:09.630
this terminate of 1 over the square root

666
00:28:09.630 --> 00:28:12.270
of 1 minus V squared over C squared. It pops

667
00:28:12.270 --> 00:28:14.590
up everywhere. Time dilation, Lorentz

668
00:28:14.590 --> 00:28:17.270
contraction, all of those things. It's the

669
00:28:17.270 --> 00:28:17.950
same factor.

670
00:28:19.610 --> 00:28:22.130
Andrew Dunkley: Suggest to Colin, um, if he wants to read the

671
00:28:22.130 --> 00:28:24.030
Human Epoch, Part one, uh,

672
00:28:25.450 --> 00:28:27.130
there is an explanation of it in there.

673
00:28:27.610 --> 00:28:30.450
Professor Fred Watson: This is your trilogy. Yes, part one

674
00:28:30.450 --> 00:28:32.450
of the trilogy. I think that's what you

675
00:28:32.450 --> 00:28:35.329
probably should do, Colin. Uh, and then you

676
00:28:35.329 --> 00:28:37.530
can bug Andrew about it.

677
00:28:38.170 --> 00:28:40.130
Andrew Dunkley: Well, I've already had a few people come to

678
00:28:40.130 --> 00:28:43.010
me and say, hang on a minute, hang on

679
00:28:43.010 --> 00:28:45.610
a minute. How did you figure that out?

680
00:28:45.850 --> 00:28:48.050
Professor Fred Watson: As you say, you're a science fiction writer.

681
00:28:48.050 --> 00:28:50.150
You can say whatever you want.

682
00:28:50.150 --> 00:28:50.510
Professor Fred Watson: Yeah.

683
00:28:50.510 --> 00:28:52.810
Andrew Dunkley: But I like. I like to get things right, so.

684
00:28:52.810 --> 00:28:54.790
Professor Fred Watson: Uh. Yeah, well, you should. That's right.

685
00:28:55.590 --> 00:28:58.070
Andrew Dunkley: All right. Uh, Colin, that's a fun question.

686
00:28:58.070 --> 00:29:00.230
And it is a really great film. If.

687
00:29:00.550 --> 00:29:03.110
If you haven't seen it. It's still one of the

688
00:29:03.110 --> 00:29:05.670
top picks on some of those, um, streaming

689
00:29:05.670 --> 00:29:07.830
platforms. Because it's, uh. It's such a.

690
00:29:07.990 --> 00:29:10.910
It's almost a delightful film in. In some

691
00:29:10.910 --> 00:29:11.270
ways.

692
00:29:11.750 --> 00:29:13.430
Professor Fred Watson: Yeah. I thought it was a comedy, actually.

693
00:29:13.590 --> 00:29:14.940
Andrew Dunkley: Yeah, it bordered on that.

694
00:29:15.090 --> 00:29:15.290
Speaker D: That.

695
00:29:15.290 --> 00:29:15.730
Professor Fred Watson: Yeah.

696
00:29:15.730 --> 00:29:16.170
Speaker D: Yeah.

697
00:29:16.170 --> 00:29:19.050
Andrew Dunkley: And it sort of. It sort of had a little

698
00:29:19.050 --> 00:29:21.330
bit of the Muppet show in it at times,

699
00:29:22.130 --> 00:29:24.570
but. But it really was a great storey. I

700
00:29:24.570 --> 00:29:25.050
loved it.

701
00:29:25.050 --> 00:29:25.410
Professor Fred Watson: Yeah.

702
00:29:25.410 --> 00:29:27.450
Andrew Dunkley: Yeah, yeah. Thanks, Colin. Great to hear from

703
00:29:27.450 --> 00:29:29.330
you. Thanks to everyone who sent us

704
00:29:29.330 --> 00:29:31.490
questions. Don't forget you can do the same

705
00:29:31.490 --> 00:29:34.290
via our website, space nutspodcast.com space

706
00:29:34.290 --> 00:29:37.210
nuts IO and just click

707
00:29:37.210 --> 00:29:39.090
on the Ask Me Anything tab at the top. And

708
00:29:39.090 --> 00:29:40.570
don't forget to tell us who you are and where

709
00:29:40.570 --> 00:29:41.850
you're from. And have a look around while

710
00:29:41.850 --> 00:29:43.490
you're there. And don't forget to leave

711
00:29:43.490 --> 00:29:46.300
reviews wherever you listen or watch us. Um,

712
00:29:47.070 --> 00:29:49.310
they help. Don't know who they help. I don't

713
00:29:49.310 --> 00:29:50.990
know why they help, but apparently they help.

714
00:29:51.860 --> 00:29:53.830
Uh, unless they're not good reviews, then

715
00:29:53.830 --> 00:29:55.790
they don't help. See,

716
00:29:56.430 --> 00:29:59.350
that's, you know, that's harder to

717
00:29:59.350 --> 00:30:02.080
explain than time dilation. Uh, and thank,

718
00:30:02.080 --> 00:30:04.110
uh, you, Fred Watson, for your help today.

719
00:30:04.110 --> 00:30:05.390
Couldn't have done it without you.

720
00:30:05.900 --> 00:30:07.190
Professor Fred Watson: Uh, I don't think I could have done it

721
00:30:07.190 --> 00:30:09.550
without you either, Andrew. So there you go.

722
00:30:10.110 --> 00:30:12.470
Just as well we're here. You're welcome. And

723
00:30:12.470 --> 00:30:13.210
we'll talk again soon.

724
00:30:13.760 --> 00:30:15.160
Andrew Dunkley: We will. Professor Fred Watson Watson,

725
00:30:15.160 --> 00:30:16.960
astronomer at large, and thanks to Huw in the

726
00:30:16.960 --> 00:30:19.200
studio. Couldn't be here due to an issue with

727
00:30:19.200 --> 00:30:21.960
time dilation, but we're expecting him in the

728
00:30:21.960 --> 00:30:24.760
year 2154. And from me, Andrew

729
00:30:24.760 --> 00:30:26.560
Dunkley. Thanks for your company. We'll see

730
00:30:26.560 --> 00:30:28.440
you on the next episode of Space Nuts. Bye

731
00:30:28.440 --> 00:30:30.640
Bye. Oh, hang on. Bye Bye.

732
00:30:32.000 --> 00:30:34.200
You've been listening to the Space Nuts

733
00:30:34.200 --> 00:30:37.200
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734
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735
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