Cosmic Questions, Gravitational Waves & the Mysteries of Space-Time | Space Nuts: Astronomy...

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Language: en

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You are listening to another wonderful


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episode of Space Nuts and I am your host


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for today, Heidi Compo. Well, our


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beloved Andrew Dunley is out on holiday.


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Don't worry, he will be back soon. But


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the brains and brun of the show, your


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beloved Fred Watson is here with us


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today. Fred, hello.


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Heidi, you ready to answer some


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questions on our Q&A episode today?


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Yeah, look, um, Q&A is the real meat of


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Space Nuts because we love people


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telling us what they want to hear about.


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It's far better than me spouting on


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things that they don't want to hear


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about. So, yep, sounds ready to go. All


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ready to go. And we we get just such a


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wonderful diverse range of questions


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from our listeners. Um, starting, you


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know, today we have uh Thomas. Dear


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Professor Fred Watson, my name is Thomas


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Wood. I'm a year 11 student doing my


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research project on the question and the


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question that I have is what is the


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chance of a habitable planet being found


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here's the key word within our lifetime.


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So what do you think Fred within our


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lifetime? Yeah I think I mean um we're


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talking here about planets of other


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stars uh exoplanets um it doesn't really


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matter whether they're habitable or not


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because they're so far away. we're never


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going to manage to get to them within


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what you might call a human time scale.


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Uh but there there are certainly


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candidates already for habitable planets


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among the five or 6 thousand exoplanets


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that we know of today and there are more


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being discovered all the time. There are


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planets that sit within the habitable


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zone of their parent star um and may


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have atmospheres that could sustain


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life. Those have not yet been confirmed.


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They've not been definitively confirmed,


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but I do think they will be within our


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lifetime. And probably Thomas, as a year


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11 students, your lifetime is rather


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longer than mine is. Uh but uh but


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that's all right. I can deal with that.


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Uh I think we'll find them within my


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lifetime. There you go. That's putting


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the that's putting the odds on it.


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Well, Fred, I think you have certainly


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done a lot with your lifetime so far,


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and you have really broken broken the


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ground for so many more to follow. Uh,


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our next question is an audio question.


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This is Adriano from Florence, Italy.


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Hi, Father Andreo. This is Adriano from


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Florence in Italy. I was listening to a


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conversation about LIGO, so the laser


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interferometer, where they explain that


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by measuring the gravitational waves


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from two colliding black holes, for


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example, they can also estimate the the


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mass of the two objects. Can you please


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explain how they can do that? And they


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also mention that with a much more


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sizable instrument, we should be able to


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measure the gravitational waves from the


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big bang. Is this correct? And if so, h


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will we be able to estimate the mass of


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the entire universe and therefore to


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confirm or deny the hypothesis around


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the dark energy and dark matter. Thank


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you guys for your inspiring podcast.


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Bye-bye. These are fantastic questions


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from Adriano. Really, you know, on on


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the edge of our knowledge really. And


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it's a good question. How? So, LIGO uh


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as you said, the laser interferometer


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gravitational wave observatory


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uh is one of several gravitational wave


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observatories. Now, LIGO was the first


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to actually detect gravitational waves


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back in 2015.


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Uh and what we saw was so gravitational


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waves are formed by vibrations in space


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and waves move through space uh which


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you know is is is they're basically uh


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propagated by the vibrations the waves


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are propagated by the vibrations of


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space. Uh because space is flexible.


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It's uh 100 billion billion times more


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rigid than steel but it's still


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flexible. So uh what we have is this uh


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phenomenon where we can actually measure


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those vibrations directly. And it turns


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out that LIGO is uh sensitive to


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gravitational waves with the same sort


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of frequency as the audio waves that we


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hear through our ears. Uh so audio waves


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are frequencies of a few hundred khertz


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and the gravitational waves that LIGO is


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sensitive to are the same. And when you


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look at the traces of these waves, you


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can see them in great detail and measure


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the way they change as two black holes


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or neutron stars combined together. Uh


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because there's a characteristic signal.


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It's called the chirp. I'll I'll do one


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for you, Heidi. Uh because I haven't


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chirped to you before. Uh if you listen


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to the audio, it sounds like


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uh and the chirp at the end is when the


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gravitational waves, sorry, the black


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holes actually emerge. They come


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together. Uh and it's the way that


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signal changes over those few tens of


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seconds uh at the end of their lives


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that let you model exactly what it is


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that is coming together. you can model


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the the objects that are colliding by


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analyzing that waveform in detail. So


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that's how it's


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done.


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Uh you don't look as though you believe


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me there. I uh I just think uh um Adria


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um Adriana's question was a little bit


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over my um


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IQ um or at least my knowledge base. But


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this sounds very fantastic and I'm very


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excited for all the people who


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understood um Fred's explanation. Let's


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go to just finish off his his other


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question though because that's really


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interesting. He he says with a bigger


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interpherometer could you detect the big


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bang and the answer is uh basically no.


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You need something quite different. So


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as I said the the LIGO and its ilk are


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sensitive to gravitational waves with um


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kilohertz frequencies. So a few a few


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hundred uh cycles per second as we used


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to call it.


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Uh, did I say kilohertz? Yes, I meant


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the wrong. Well, I'm talking. Yeah,


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kilhertz are a bit high. It's hundreds


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of hertz rather than kilohertz. So, you


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know, 500 600 htz, kilohertz is a


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thousand obviously. So, just replay that


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bit. Anyway, um the bottom line is to


00:07:02.000 --> 00:07:03.670
look for phenomena in the early


00:07:03.680 --> 00:07:05.909
universe. And it's not so much the big


00:07:05.919 --> 00:07:07.909
bang itself as the inflationary period


00:07:07.919 --> 00:07:09.430
that followed it when the universe


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expanded by 10 ^ 50 and 10 the minus 33


00:07:13.680 --> 00:07:16.629
of a second. Uh which is just beggars


00:07:16.639 --> 00:07:19.510
the imagination. But for to pick up


00:07:19.520 --> 00:07:22.950
phenomena like that you need uh you need


00:07:22.960 --> 00:07:26.309
to be sensitive to gravitational waves


00:07:26.319 --> 00:07:30.870
with nanoertz frequencies. That means


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um how can I put it? uh a billionth of a


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of a a billionth of a cycle per second.


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In other words, they make one cycle over


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a very long period of time, years,


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decades, maybe even millions of years


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with some of them. So you you never see


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the vibrations. You just see part of one


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cycle because it's so slow. The period


00:07:51.840 --> 00:07:54.869
of these vibrations is so slow. And so


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you need different technologies to do


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that. And people are working on those.


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And indeed, we've spoken about some on


00:08:01.120 --> 00:08:04.070
Space Nuts in the past. Yeah. People


00:08:04.080 --> 00:08:06.150
just like people just like you. I'd say


00:08:06.160 --> 00:08:08.710
people like you and me, but probably a


00:08:08.720 --> 00:08:12.710
little bit more people like you.


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nordvpn.com/spacenuts. All right, let's


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get back to the show.


00:09:43.360 --> 00:09:47.190
And I feel space nuts. Um our our next


00:09:47.200 --> 00:09:48.790
question is actually from your side of


00:09:48.800 --> 00:09:52.509
the world and it uh it's from an um


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Anthony love the show of course my


00:09:55.200 --> 00:09:57.670
question is even though the moon's orbit


00:09:57.680 --> 00:10:01.670
is tilted relative to the earth only by


00:10:01.680 --> 00:10:04.550
se or sorry by only 7° why does it


00:10:04.560 --> 00:10:07.269
appear to shift so much in the sky


00:10:07.279 --> 00:10:09.990
tonight for example it is really low in


00:10:10.000 --> 00:10:12.310
the north from my location in Sydney but


00:10:12.320 --> 00:10:14.230
at other times sometimes not too far


00:10:14.240 --> 00:10:17.350
apart it is almost overhead. It must be


00:10:17.360 --> 00:10:19.269
simple geometry, but the differences


00:10:19.279 --> 00:10:22.870
seem far too great to be 7 or 14°. It


00:10:22.880 --> 00:10:25.829
seems like much more than 45°. Certainly


00:10:25.839 --> 00:10:28.829
more than the first three lengths.


00:10:28.839 --> 00:10:31.269
Thanks. And that's from uh Anthony from


00:10:31.279 --> 00:10:33.590
Sydney, Australia. Yeah, he's probably


00:10:33.600 --> 00:10:36.389
not very far from where I'm sitting now.


00:10:36.399 --> 00:10:39.829
Hello, Anthony. So, 7 to 7 to 14 degrees


00:10:39.839 --> 00:10:43.190
away from you. Yes, it could be. Uh so


00:10:43.200 --> 00:10:46.310
actually it's 5° not 7°. Uh the tilt of


00:10:46.320 --> 00:10:50.230
the moon's orbit is 5° but


00:10:50.240 --> 00:10:53.030
uh the main point is that it's tilt that


00:10:53.040 --> 00:10:57.269
5° is with respect to the ecliptic uh


00:10:57.279 --> 00:10:59.590
which is the plane of the earth's orbit


00:10:59.600 --> 00:11:01.750
in space. So


00:11:01.760 --> 00:11:03.829
uh and and in the sky the ecliptic is


00:11:03.839 --> 00:11:07.590
the path of the sun through the sky. So


00:11:07.600 --> 00:11:12.509
uh 5° tilt to the ecliptic uh means that


00:11:12.519 --> 00:11:15.269
effectively the moon follows the sun's


00:11:15.279 --> 00:11:17.829
path through the sky with a bit of 5


00:11:17.839 --> 00:11:21.110
degrees either side of it. So is as as


00:11:21.120 --> 00:11:23.829
Anthony says that's not very much but


00:11:23.839 --> 00:11:25.829
the bottom line is of course the sun's


00:11:25.839 --> 00:11:27.750
path through the sky is tilted at 23 and


00:11:27.760 --> 00:11:30.150
a half degrees with respect to the


00:11:30.160 --> 00:11:34.069
equator and that's why um we see such


00:11:34.079 --> 00:11:35.910
large variations. So if you think about


00:11:35.920 --> 00:11:39.350
what the sun does in a year, the moon


00:11:39.360 --> 00:11:41.990
does more or less the same thing in a


00:11:42.000 --> 00:11:44.310
month because it goes around the


00:11:44.320 --> 00:11:46.710
ecliptic, 5 degrees one side or the


00:11:46.720 --> 00:11:48.069
other of it, but more or less going


00:11:48.079 --> 00:11:50.230
around the ecliptic in one month, which


00:11:50.240 --> 00:11:52.389
is why over very short periods of time


00:11:52.399 --> 00:11:55.750
you see the moon in very very diff


00:11:55.760 --> 00:11:58.389
uh in the sky. Um, one little


00:11:58.399 --> 00:12:00.790
characteristic, and this might


00:12:00.800 --> 00:12:03.030
illuminate one of the comments that, um,


00:12:03.040 --> 00:12:07.350
uh, Anthony made, is that when you're


00:12:07.360 --> 00:12:10.150
near the solstesses, either the summer


00:12:10.160 --> 00:12:12.949
solstice, which for us in Australia, uh,


00:12:12.959 --> 00:12:15.030
is in December, the sun is at its


00:12:15.040 --> 00:12:17.829
highest in the sky, uh, or the winter


00:12:17.839 --> 00:12:19.590
solstice, which for us in Australia is


00:12:19.600 --> 00:12:22.550
June. Um then the moon in its path


00:12:22.560 --> 00:12:25.350
through the sky basically uh when it's


00:12:25.360 --> 00:12:28.230
full a full moon is exactly opposite


00:12:28.240 --> 00:12:30.230
where the sun is. So when the sun's very


00:12:30.240 --> 00:12:32.550
high in the sky a full moon is very low


00:12:32.560 --> 00:12:35.110
in the sky. It's right opposite it with


00:12:35.120 --> 00:12:38.389
within five degrees either side. Uh so I


00:12:38.399 --> 00:12:40.629
always think of that when I look at a


00:12:40.639 --> 00:12:43.509
full moon um I imagine it's where the


00:12:43.519 --> 00:12:46.550
sun will be in six months time uh at the


00:12:46.560 --> 00:12:49.269
different time of year which is kind of


00:12:49.279 --> 00:12:51.509
quite cute really in a peculiar sort of


00:12:51.519 --> 00:12:55.030
way. Um so yes it's a good observation


00:12:55.040 --> 00:12:56.790
uh but the reason for it is as you said


00:12:56.800 --> 00:12:58.710
it's geometry.


00:12:58.720 --> 00:13:01.350
I uh I I never thought of that. That's a


00:13:01.360 --> 00:13:04.230
that's a quite a cool little tidbit. I'm


00:13:04.240 --> 00:13:05.750
just I'm thinking back, this is a little


00:13:05.760 --> 00:13:07.750
bit of a a side story, but I got


00:13:07.760 --> 00:13:09.750
married. I insisted I told my husband I


00:13:09.760 --> 00:13:11.509
wanted to do an astronomy kind of themed


00:13:11.519 --> 00:13:13.590
wedding. And so we got married under we


00:13:13.600 --> 00:13:15.590
chose the October full moon, the


00:13:15.600 --> 00:13:18.230
hunter's moon, and we got married and


00:13:18.240 --> 00:13:20.629
then we immediately um the next day we


00:13:20.639 --> 00:13:22.230
were driving across the country because


00:13:22.240 --> 00:13:24.310
I was from Utah, he was in Florida at


00:13:24.320 --> 00:13:25.990
the time. So we started our road trip to


00:13:26.000 --> 00:13:27.910
Florida the day after we got married.


00:13:27.920 --> 00:13:29.990
And I just remember um because we did


00:13:30.000 --> 00:13:31.829
our our our full moon wedding and I got


00:13:31.839 --> 00:13:33.110
married right at the time that the moon


00:13:33.120 --> 00:13:35.110
was supposed to be at its fullest. I'm a


00:13:35.120 --> 00:13:36.470
little bit of a weirdo. But then the


00:13:36.480 --> 00:13:40.069
next day the moon was so low in the sky


00:13:40.079 --> 00:13:42.550
and bright red. I just remember it was


00:13:42.560 --> 00:13:44.949
the most brilliant looking thing I've


00:13:44.959 --> 00:13:46.550
ever seen. And so just really kind of


00:13:46.560 --> 00:13:48.389
thinking about Antony's question with


00:13:48.399 --> 00:13:49.670
you know when we got married it was up


00:13:49.680 --> 00:13:51.269
in the sky and then the very next day


00:13:51.279 --> 00:13:53.509
it's right down low on the horizon like


00:13:53.519 --> 00:13:55.509
a movie. It was like a like like almost


00:13:55.519 --> 00:13:58.150
like a Lawrence of Arabia type kind of


00:13:58.160 --> 00:14:01.110
uh look. It was very cool. Um Heidi, I'm


00:14:01.120 --> 00:14:03.910
going to pick up on that today because I


00:14:03.920 --> 00:14:06.389
can't resist this. Many and I too had a


00:14:06.399 --> 00:14:09.350
an an astronomical wedding.


00:14:09.360 --> 00:14:12.150
We got married. Uh and this is why I'm


00:14:12.160 --> 00:14:14.629
picking up on this. Uh six years ago


00:14:14.639 --> 00:14:17.189
today, it's actually today is our


00:14:17.199 --> 00:14:20.310
anniversary. Oh, happy anniversary.


00:14:20.320 --> 00:14:21.910
Thank you very much. Yeah, we we've been


00:14:21.920 --> 00:14:23.590
together for nearly 20 years, but it


00:14:23.600 --> 00:14:25.990
took us quite a while to get married. Uh


00:14:26.000 --> 00:14:28.550
six years ago today, we got married on


00:14:28.560 --> 00:14:31.590
the summit of Halakala on Maui, which


00:14:31.600 --> 00:14:34.550
has uh a number of large significant


00:14:34.560 --> 00:14:37.110
telescopes on it, including Pan Stars 2,


00:14:37.120 --> 00:14:40.389
the asteroid guardian telescope uh and


00:14:40.399 --> 00:14:43.430
the Daniel Kui uh solar telescope, the


00:14:43.440 --> 00:14:44.870
biggest solar telescope in the world.


00:14:44.880 --> 00:14:46.470
They were right behind us when we got


00:14:46.480 --> 00:14:49.030
married at 10,000 ft on the summit of


00:14:49.040 --> 00:14:51.590
Maui. and I got wonderfully sunburned on


00:14:51.600 --> 00:14:54.629
the top of my head.


00:14:54.639 --> 00:14:56.389
Oh, that's such a beautiful story. Well,


00:14:56.399 --> 00:14:59.829
congrats to you and congrats to Congrats


00:14:59.839 --> 00:15:01.750
to yours. And that's a that's such a


00:15:01.760 --> 00:15:02.790
beautiful story. I guess we're


00:15:02.800 --> 00:15:05.990
dedicating this episode to um our our


00:15:06.000 --> 00:15:08.870
significant others and the That's right.


00:15:08.880 --> 00:15:11.990
Yeah. And the moon. That's right. Yeah.


00:15:12.000 --> 00:15:13.590
Sorry. Sorry to hijack that


00:15:13.600 --> 00:15:15.509
conversation. Oh, no. That was uh that


00:15:15.519 --> 00:15:16.949
was well that was a fun you know maybe


00:15:16.959 --> 00:15:19.430
maybe people are curious about your um


00:15:19.440 --> 00:15:21.670
you know your personal personal um


00:15:21.680 --> 00:15:23.670
experiences with space cuz I think you


00:15:23.680 --> 00:15:25.110
know sometimes it's nice to add in


00:15:25.120 --> 00:15:27.590
infuse a little bit of the personal love


00:15:27.600 --> 00:15:31.269
for space too.


00:15:31.279 --> 00:15:34.230
Okay we checked all four systems with


00:15:34.240 --> 00:15:37.430
space nets. Um our next uh question is


00:15:37.440 --> 00:15:41.069
an audio question and this is Mikey from


00:15:41.079 --> 00:15:44.389
Illinois USA. Hey friend Andrew. This is


00:15:44.399 --> 00:15:46.870
Mikey once again from Illinois in the US


00:15:46.880 --> 00:15:49.829
of A. I'm just wondering if you guys


00:15:49.839 --> 00:15:51.749
have any room in your house for me and


00:15:51.759 --> 00:15:54.110
my family. I'm just kid unless you're


00:15:54.120 --> 00:15:56.550
serious. I'm just joking. Unless you


00:15:56.560 --> 00:15:59.430
want me to. I'm just kidding. Keep it in


00:15:59.440 --> 00:16:04.790
mind. Um so I know that space can bend.


00:16:04.800 --> 00:16:07.350
Uh space can warp. Space can ripple.


00:16:07.360 --> 00:16:10.710
Space can supposedly tear.


00:16:10.720 --> 00:16:13.749
I was curious as to what it means for


00:16:13.759 --> 00:16:15.990
space to actually tear. Like, have we


00:16:16.000 --> 00:16:17.550
seen


00:16:17.560 --> 00:16:20.310
examples in real life of space tearing


00:16:20.320 --> 00:16:22.150
and what would that look like or is it


00:16:22.160 --> 00:16:24.629
just we know it can but we haven't seen


00:16:24.639 --> 00:16:26.550
it? Um, yeah, I was just hoping you guys


00:16:26.560 --> 00:16:28.230
could explain that a little bit more.


00:16:28.240 --> 00:16:30.310
Appreciate you guys. Love the show. What


00:16:30.320 --> 00:16:33.590
a what an interesting question. Um, and


00:16:33.600 --> 00:16:36.430
it's it it it it is


00:16:36.440 --> 00:16:39.509
hypothetical the idea of space tearing


00:16:39.519 --> 00:16:42.069
uh because we've never ever seen


00:16:42.079 --> 00:16:44.870
anything symptomatic of tearing space


00:16:44.880 --> 00:16:47.430
either here on our planet or in the


00:16:47.440 --> 00:16:50.150
wider universe and it would have to be


00:16:50.160 --> 00:16:52.629
under very very extreme circumstances


00:16:52.639 --> 00:16:57.189
that it would happen. Um so uh by


00:16:57.199 --> 00:16:59.110
extreme I mean space being stretched


00:16:59.120 --> 00:17:00.189
beyond its


00:17:00.199 --> 00:17:03.670
limits. And the reason why this is a


00:17:03.680 --> 00:17:06.630
popular notion is because of the


00:17:06.640 --> 00:17:12.470
discovery back in uh back in 1998


00:17:12.480 --> 00:17:17.350
uh that space is ex accelerating in its


00:17:17.360 --> 00:17:19.909
expansion. We've known since 1929 that


00:17:19.919 --> 00:17:21.990
the universe is expanding. That's taking


00:17:22.000 --> 00:17:24.710
space with it. Uh but since 1998, we've


00:17:24.720 --> 00:17:27.829
known that that expansion has been ever


00:17:27.839 --> 00:17:29.630
faster, ever more rapid. It's


00:17:29.640 --> 00:17:32.230
accelerating. Uh and so that's given


00:17:32.240 --> 00:17:35.590
rise to the idea of if this goes on into


00:17:35.600 --> 00:17:37.909
the far distant future, are we going to


00:17:37.919 --> 00:17:40.190
get to a situation where space is so


00:17:40.200 --> 00:17:43.669
stretched that it falls apart? Uh and


00:17:43.679 --> 00:17:47.190
that gives rise to the notion of uh the


00:17:47.200 --> 00:17:50.630
big rip. And actually the the best place


00:17:50.640 --> 00:17:53.270
I can direct Mikey to on the web because


00:17:53.280 --> 00:17:56.710
it's explained very um I won't say


00:17:56.720 --> 00:17:58.549
concisely, it's explored in great


00:17:58.559 --> 00:18:01.750
detail, but it's quite easy to read. Uh


00:18:01.760 --> 00:18:06.470
is the big rip uh entry on Wikipedia. Uh


00:18:06.480 --> 00:18:09.029
I'm a big fan of Wikipedia. Uh and the


00:18:09.039 --> 00:18:11.350
big rip entry is really quite


00:18:11.360 --> 00:18:14.350
extraordinary because it talks about the


00:18:14.360 --> 00:18:17.909
hypothesis that space could tear. It


00:18:17.919 --> 00:18:20.789
talks a little bit about the work that's


00:18:20.799 --> 00:18:22.870
been done on this, the research that has


00:18:22.880 --> 00:18:25.669
been carried out in a in a serious um


00:18:25.679 --> 00:18:28.070
you know academic manner as to what


00:18:28.080 --> 00:18:29.990
might constitute space being ripped


00:18:30.000 --> 00:18:34.230
apart. Uh and you can you can sort of


00:18:34.240 --> 00:18:36.150
define that in terms of the various


00:18:36.160 --> 00:18:39.990
fundamental forces of nature and um


00:18:40.000 --> 00:18:42.470
there is a hypothesis that then suggests


00:18:42.480 --> 00:18:44.710
what that what might be the trigger for


00:18:44.720 --> 00:18:47.029
a big rip in terms of you know the


00:18:47.039 --> 00:18:49.669
tension that is involved.


00:18:49.679 --> 00:18:52.390
uh and that one of the authors of that


00:18:52.400 --> 00:18:54.070
hypothesis is Robert Caldwell of


00:18:54.080 --> 00:18:56.789
Dartmouth College who presents us with a


00:18:56.799 --> 00:18:59.510
formula which defines when the big rip


00:18:59.520 --> 00:19:02.150
will take place. Uh it's quite a neat


00:19:02.160 --> 00:19:03.750
formula. It includes things like the


00:19:03.760 --> 00:19:06.310
Hubble constant and the barionic mass


00:19:06.320 --> 00:19:08.230
content of the universe. It's all there


00:19:08.240 --> 00:19:10.870
on the page. Uh and I think the bottom


00:19:10.880 --> 00:19:13.350
line is uh is it 20 billion years? I


00:19:13.360 --> 00:19:14.950
think something like that. Oh no, wait a


00:19:14.960 --> 00:19:17.430
minute. The earliest is 152 billion


00:19:17.440 --> 00:19:19.669
years time. That's when space we've got


00:19:19.679 --> 00:19:22.150
time. Yeah. 152 billion years. Put it in


00:19:22.160 --> 00:19:24.390
your diary, Mikey, because that's when


00:19:24.400 --> 00:19:27.110
you will find the first example of space


00:19:27.120 --> 00:19:31.270
being ripped. Oh my. Well, our very last


00:19:31.280 --> 00:19:33.909
question is um from from my side of the


00:19:33.919 --> 00:19:36.950
world again. So, we got Greg from


00:19:36.960 --> 00:19:39.110
Minnesota. So, he says, "Hello from


00:19:39.120 --> 00:19:41.909
Minnesota, USA. I'm Greg and I have a


00:19:41.919 --> 00:19:45.350
question about the cosmic jerk. And no,


00:19:45.360 --> 00:19:47.990
I don't mean Fred.


00:19:48.000 --> 00:19:51.350
Oh, Fred. Uh, and his question is, the


00:19:51.360 --> 00:19:53.590
change of position over time is


00:19:53.600 --> 00:19:56.150
velocity, and the change of velocity


00:19:56.160 --> 00:19:59.350
over time is acceleration. But we don't


00:19:59.360 --> 00:20:01.510
need to stop there. The change of


00:20:01.520 --> 00:20:04.789
acceleration over time is called jerk.


00:20:04.799 --> 00:20:07.350
We know the universe is accelerating,


00:20:07.360 --> 00:20:09.990
but but have we been able to measure


00:20:10.000 --> 00:20:12.230
whether or not it's accelerating at a


00:20:12.240 --> 00:20:15.270
constant rate? Love the podcast. Keep up


00:20:15.280 --> 00:20:18.230
the good work. If you're curious, the


00:20:18.240 --> 00:20:20.950
next derivatives after jerk are snap,


00:20:20.960 --> 00:20:24.029
snap, crackle, and pop.


00:20:24.039 --> 00:20:27.590
Yeah. So, um I'll I'll refrain from


00:20:27.600 --> 00:20:29.750
using the term jerk since it's been


00:20:29.760 --> 00:20:33.430
applied to me. Um and give it its proper


00:20:33.440 --> 00:20:36.190
name, which is uh the rate of change of


00:20:36.200 --> 00:20:38.549
acceleration. So, acceleration is the


00:20:38.559 --> 00:20:40.230
rate of change of velocity. Velocity is


00:20:40.240 --> 00:20:42.149
the rate of change of position as


00:20:42.159 --> 00:20:44.789
exactly as as Greg says. I was uh


00:20:44.799 --> 00:20:45.990
thinking this question was going to be


00:20:46.000 --> 00:20:47.430
for me for a second. I was like, "Wait a


00:20:47.440 --> 00:20:48.789
second. That's what I do my research


00:20:48.799 --> 00:20:50.590
in."


00:20:50.600 --> 00:20:55.909
Yes. So, yeah. So, so um but but but


00:20:55.919 --> 00:20:59.190
Greg's question is is very very uh


00:20:59.200 --> 00:21:01.909
topical at the moment because yes, we've


00:21:01.919 --> 00:21:03.510
known that the universe is accelerating


00:21:03.520 --> 00:21:05.909
as I said a few minutes ago since 1998.


00:21:05.919 --> 00:21:09.110
Discovery made by an Australian and a a


00:21:09.120 --> 00:21:12.149
US scientist in working independently.


00:21:12.159 --> 00:21:16.950
Um that discovery immediately led to the


00:21:16.960 --> 00:21:19.909
question is the acceleration changing in


00:21:19.919 --> 00:21:21.510
other words is there a rate of change of


00:21:21.520 --> 00:21:24.390
acceleration and that's a very hard uh


00:21:24.400 --> 00:21:27.990
observation to make um you need to look


00:21:28.000 --> 00:21:31.110
at the universe over the widest possible


00:21:31.120 --> 00:21:33.510
range of look back times. So you want to


00:21:33.520 --> 00:21:36.070
look back 11 billion years if you can uh


00:21:36.080 --> 00:21:38.470
you know sort of 78 of the age of the


00:21:38.480 --> 00:21:42.549
universe. uh and so what's happened uh


00:21:42.559 --> 00:21:45.510
recently is u uh something called uh


00:21:45.520 --> 00:21:47.590
DESI which is the dark energy survey


00:21:47.600 --> 00:21:49.990
instrument and dark energy is by the way


00:21:50.000 --> 00:21:51.990
the mechanism which we think is causing


00:21:52.000 --> 00:21:54.149
the universe to expand that space has an


00:21:54.159 --> 00:21:57.190
energy of its own until now we've


00:21:57.200 --> 00:21:59.750
believed that was a constant that the


00:21:59.760 --> 00:22:01.909
acceleration of the universe was a


00:22:01.919 --> 00:22:05.510
constant but DESI the dark energy survey


00:22:05.520 --> 00:22:09.110
instrument on a telescope uh in Arizona


00:22:09.120 --> 00:22:11.270
based on the male telescope, the 4 meter


00:22:11.280 --> 00:22:14.710
telescope at Kick Peak. Uh that seems to


00:22:14.720 --> 00:22:17.350
be indicating and it's still not


00:22:17.360 --> 00:22:20.789
speculative. It's still u um you know


00:22:20.799 --> 00:22:23.350
one of these results that's still got a


00:22:23.360 --> 00:22:25.029
question mark over it, but it seems to


00:22:25.039 --> 00:22:26.390
indicate that the acceleration is


00:22:26.400 --> 00:22:28.950
slowing down. And slowing down the


00:22:28.960 --> 00:22:31.430
acceleration is a good thing because it


00:22:31.440 --> 00:22:35.029
might put off the big rip beyond 152


00:22:35.039 --> 00:22:37.510
billion years. might push it back into


00:22:37.520 --> 00:22:41.110
the more distant horizon. Uh so we will


00:22:41.120 --> 00:22:43.830
it remains to be seen. Uh but I think


00:22:43.840 --> 00:22:45.510
the odds are that over the next few


00:22:45.520 --> 00:22:47.270
years we'll find compelling evidence


00:22:47.280 --> 00:22:50.070
that the acceleration of the universe's


00:22:50.080 --> 00:22:53.270
expansion is slowing down. And that's a


00:22:53.280 --> 00:22:55.909
mystery because that needs a mechanism


00:22:55.919 --> 00:22:57.669
and it probably suggests there are new


00:22:57.679 --> 00:23:00.230
physics that we do not understand uh


00:23:00.240 --> 00:23:02.710
that have yet to be determined and it


00:23:02.720 --> 00:23:05.510
opens up all kinds of areas of research


00:23:05.520 --> 00:23:07.190
uh which seems like a really good way to


00:23:07.200 --> 00:23:11.110
wrap up this Q&A session of Space Nut.


00:23:11.120 --> 00:23:14.230
Absolutely. And um and I'm and um I'll


00:23:14.240 --> 00:23:17.270
I'll tie that in with uh love, another


00:23:17.280 --> 00:23:19.350
one of life's greatest mysteries. Uh,


00:23:19.360 --> 00:23:21.430
since we're talking about our our loved


00:23:21.440 --> 00:23:23.990
ones, if there is somebody that you love


00:23:24.000 --> 00:23:26.549
and you would love to share this podcast


00:23:26.559 --> 00:23:29.750
with, we would be just tickled if you


00:23:29.760 --> 00:23:31.909
could tell everybody that you love and


00:23:31.919 --> 00:23:33.270
maybe some people that you don't even


00:23:33.280 --> 00:23:34.870
really care for, but you sit next to


00:23:34.880 --> 00:23:36.950
them at the office. Uh, tell your


00:23:36.960 --> 00:23:38.470
friends, tell your family, tell the


00:23:38.480 --> 00:23:40.070
people you don't like, tell your dog,


00:23:40.080 --> 00:23:42.630
tell your cat um about Space Nuts. We


00:23:42.640 --> 00:23:45.830
are here for you. We've got our uh


00:23:45.840 --> 00:23:48.710
question and answer episodes and our


00:23:48.720 --> 00:23:50.149
more I guess uh what do we call this?


00:23:50.159 --> 00:23:52.390
More narrative story style episodes


00:23:52.400 --> 00:23:55.270
every week. And so Fred, do you have


00:23:55.280 --> 00:23:56.950
anything else you want to add before we


00:23:56.960 --> 00:23:59.029
sign off for the day? I think we've


00:23:59.039 --> 00:24:01.990
covered uh so much of the big mysteries


00:24:02.000 --> 00:24:03.830
today that we should just go away with


00:24:03.840 --> 00:24:05.590
our heads spinning and try and think of


00:24:05.600 --> 00:24:07.430
some more questions for next time.


00:24:07.440 --> 00:24:09.270
Excellent. Well, hey Fred, thank you so


00:24:09.280 --> 00:24:12.070
much. This has been another episode of


00:24:12.080 --> 00:24:14.549
Space Nut. Space Nuts. You'll be


00:24:14.559 --> 00:24:18.310
listening to the Space Nuts podcast


00:24:18.320 --> 00:24:21.350
available at Apple Podcasts, Spotify,


00:24:21.360 --> 00:24:23.990
iHeart Radio, or your favorite podcast


00:24:24.000 --> 00:24:26.830
player. You can also stream on demand at


00:24:26.840 --> 00:24:29.269
byes.com. This has been another quality


00:24:29.279 --> 00:24:33.799
podcast production from byes.com.