Moon Time - What? | Space Nuts #342

[00:00:00] Hi there, thanks for joining us. This is Space Nuts. I'm your host Andrew Dunkley.

[00:00:04] Hope you can stick around. We've got a lot to talk about today. What time is it on the moon?

[00:00:09] It's Moon Time. Could be daytime, could be night time. It depends where you are,

[00:00:13] but we're talking about real time that we'll elaborate shortly. There might be a new way

[00:00:20] to find Planet Nine. We're going to look at some sun rays on Mars and the dark Big Bang theory.

[00:00:30] We'll also be answering some audience questions and much, much more on this episode of Space Nuts.

[00:00:38] 15 seconds. Guidance is internal. 10, space nuts.

[00:00:51] Space Nuts.

[00:00:54] And joining me to hash all of that out with a hash brown in hand is

[00:01:01] Fred Watson, a strong and road life. Hello, Fred. Yeah, a hash brown would go down really well

[00:01:07] actually. Thank you for mentioning it. I love them. I have two other.

[00:01:12] I know they're a hard attack for breakfast. Yeah, yeah.

[00:01:18] Welcome back to the real world and the same time zone as me.

[00:01:21] Yeah.

[00:01:21] You're still suffering from jet lag after your sojourn to Europe.

[00:01:25] It's not been too bad, thanks Andrew. I did hit the wall at nine o'clock for a couple of

[00:01:30] nights after the 9 p.m., I have to say, not 9 a.m., which would have been difficult.

[00:01:35] But yeah, it's pretty good. Thank you. So far so good.

[00:01:40] Excellent. Good group.

[00:01:41] Yeah. Oh, and there's Muscat just checking on.

[00:01:43] Muscat, we've never heard from Muscat.

[00:01:45] Wow. Well, he's just kind of looking for somebody.

[00:01:49] Yeah.

[00:01:49] I'm sure he's probably not you.

[00:01:51] Yeah, not me.

[00:01:54] Well, it's nice to hear from Muscat. Now, we've got a lot to talk about.

[00:01:58] What time is it on the moon, Fred?

[00:02:02] It's probably hash brown time, mostly.

[00:02:05] Yeah. So this is what's prompted this piece of research or investigation that's actually going

[00:02:15] on. I think it's being led from Europe, but includes pretty well all the world's space

[00:02:20] agencies. And so I think the idea is how do you define time on the moon?

[00:02:30] Do you have lots of different time zones like we have on Earth, or do you have a single lunar

[00:02:36] time zone? How does it all work? And how do you deal with nuances like the fact that the moon

[00:02:43] is a much less massive body than the Earth? It only has one eightieth of the mass of the Earth.

[00:02:49] So the gravitational time, the relativistic gravitational time dilation on the moon

[00:02:54] is different from what it was, what it is on Earth. So there's a very, very tiny difference

[00:03:00] amounting to microseconds between the way clocks stick on the moon and the way they

[00:03:05] stick on Earth. But the story kind of starts really with the fact that over

[00:03:12] our the history of our exploration of the moon, every space mission that's gone to the moon

[00:03:19] has basically set up its own time system. And usually they use the time back, you know,

[00:03:25] mission headquarters wherever that might be. That's clearly not going to work if you've got many

[00:03:33] experiments going on the moon, perhaps many simultaneous missions on the moon,

[00:03:38] where you might have a permanent base on the moon. And I can imagine that the Americans

[00:03:44] have set up a base and the Russians set up a base that will have a meeting at seven o'clock

[00:03:49] using different times. So you've got to they've got a history of not keeping up with the world on

[00:03:58] time. They stuck with the Julian calendar a lot longer than everybody else. That's true.

[00:04:04] We switched to Gregorian calendar. We were pretty slow in the in the in Britain.

[00:04:10] Yes, 1752. Is that the famous case of where there were like 11 days lost and all those people

[00:04:20] got upset because they thought they were going to die or something? Give us back our 11 days.

[00:04:25] That's exactly what happened. Yes. I can't remember the excuse me. I can't remember the date

[00:04:31] when the change was made. And I should do it because I've given talks about this stuff in

[00:04:35] the past. It's a long time ago. But yeah, 1752 there was a general election about the same time and

[00:04:42] that became a hot topic in the election, you know, the election material. Talking about a time

[00:04:49] where people still sort of didn't understand the wise and warefors of things and they thought

[00:04:55] that taking those days away kept would cause their life. Yeah. Yeah. Yeah.

[00:05:00] That's why 11 days would have turned to be. The government had stolen it. Yeah, it's a good story.

[00:05:06] Famous having your spirits stolen when your photograph is taken.

[00:05:10] That was yes along the same lines. Yeah. It's fascinating story if you want to look it up.

[00:05:15] It's on Wikipedia and a bunch of other websites. It's a really fascinating story about those

[00:05:21] catch-up days back in the day. Back in the day. That's right. And of course that

[00:05:26] that same time system spread to Australia. Yeah.

[00:05:31] That's by nefarious means, I'm sure. But coming back to the moon.

[00:05:38] Where we were? Yeah, there is a... So there's an essentially a set of discussions going on

[00:05:46] to basically to nut out an architecture that will oversee communications on the moon,

[00:05:57] navigation services on the moon and part and parcel of that is time. It's been called Lunanet.

[00:06:02] L-U-N-A-N-E-T all one word, a bit like basinuts is all one word. Lunanet is the architecture

[00:06:09] that is trying to be agreed and a comment from Xavier Ventura Travesi who is the European Space

[00:06:18] Agencies Moonlight Navigation Manager, who's coordinating the European Space Agency's contribution

[00:06:24] to Lunanet. Xavier says Lunanet is a framework of mutually agreed upon standards, protocols

[00:06:32] and interface requirements allowing future lunar missions to work together.

[00:06:37] Conceptually similar to what we did on Earth for joint use of GPS and Galileo.

[00:06:42] Now in the lunar context, we have the opportunity to agree on our interoperability

[00:06:49] approach from the very beginning before systems are actually implemented.

[00:06:53] Hello Marnie. Marnie's dropped in with you. Is that your coffee?

[00:06:57] Thank you. Told you might get a coffee. Yeah.

[00:07:01] That's great. Wow thank you. So that's basically what's happening and

[00:07:07] you know in fact there's another comment from an ASA navigation systems engineer Pietro Giordano

[00:07:15] who says timing is the crucial element. During this meeting we agreed on the importance and

[00:07:20] urgency of defining a common lunar reference time which is internationally accepted and

[00:07:26] which all lunar systems and users may refer to. A joint international effort is now being

[00:07:32] launched towards achieving this and that's really what this story is all about. It's about people

[00:07:36] talking about how we set up time on the Moon. I'm just going to ask what may be a dumb question

[00:07:44] but why can't they just go with Zulu time or international time? Well my guess is that

[00:07:50] that's what will happen. That it will be... You solved the problem. UT1 is the universal time

[00:08:00] system that is agreed upon on Earth and it comes from the International Bureau of Weights and Measures

[00:08:08] in Paris. That's I think the organisation that coordinates it all but the issue though is that

[00:08:18] if you've got like lunar GPS systems and things of that sort which by the way some radio astronomers

[00:08:24] take a pretty dim view of because they want to put a radio telescope on the far side of the Moon

[00:08:31] where you're immune from radio contamination from Earth. If you put GPS satellites in orbit

[00:08:37] around the Moon well you've kind of ruined that to start with. Anyway the issue is that if

[00:08:44] you're looking at really precise lunar timing you have got this issue of the gravitational

[00:08:53] time dilation on the Moon. There is a figure which I haven't checked this but it may well be

[00:09:04] about right because the gravitational potential on the surface of the Moon

[00:09:11] is less than the gravitational potential on the surface of the Earth. A clock on the Moon

[00:09:16] is going to run faster than one on the Earth by about 56 microseconds per day

[00:09:24] and that is significant. That is really significant because GPS systems rely on nanoseconds you know

[00:09:30] they've got to be accurate to far better precision than that. So that's really the

[00:09:36] the counter answer to your suggestion. You can't just import terrestrial time you've got to tweak it

[00:09:45] in some way. I thought if you could just make a clock that runs 0.56 microseconds faster couldn't

[00:09:52] you? Just change the speed of... Yes that's right so you've got but then you've immediately

[00:10:01] got something different from UT1 you can't just import it. You can use it as the basis but you've

[00:10:07] got to tweak it to allow for the low gravitational field. So all of this sort of thing is clearly what

[00:10:15] these people are talking about. That one that we committee. Yes that's right if in doubt

[00:10:23] former committee it's what you do. They even did that when Hans Slipper turned up with the

[00:10:29] first telescope in the Hague in early... Yes indeed in 1608 they formed a committee. That's what

[00:10:37] everybody does. Anyway there is a nice final comment from from Xavier who I mentioned earlier

[00:10:44] throughout human history exploration has actually been a key driver of improved timekeeping and

[00:10:51] geodetic reference models which is a really good point because exploration is what drove the

[00:10:57] invention of the chronometer you know the Harrison chronometer and all of that stuff so that you

[00:11:00] can find your way properly. Yeah and he goes on to say it's certainly an exciting time to do that

[00:11:05] now for the moon working towards defining an internationally agreed timescale and a common

[00:11:11] selenacentric reference which will not only ensure interoperability between the different

[00:11:19] lunar navigation systems but which will also foster a large number of research opportunities

[00:11:24] and applications in Cicilluna space. There you go that's the words from the top. Who would have

[00:11:31] thought it was so complicated to tell time on the moon? Although it was me an opportunity to

[00:11:36] razz my brother who when growing up couldn't understand how he was older than our sister

[00:11:42] because she was born in April and he was born in July so how could he be older? He didn't get

[00:11:47] the concept of years. That's interesting yeah it's always funny just hearing you try to figure it

[00:11:54] out. Oh well yes. All right so moon time is yet to be established something that they may

[00:12:02] establish is a new way to find planet nine what's that? Well I like this story. We're going to look

[00:12:08] with our eyes. Yeah that's the problem that's what we've been doing so far. It doesn't work.

[00:12:15] It's it is an issue that goes back you and I talked about this several times before but

[00:12:26] not recently which is why it was a nice story to cover. The idea of course that there are several

[00:12:33] and it's quite a large number of the objects the icy asteroids out there in the coca

[00:12:39] bell beyond the orbit of Neptune whose highly elongated orbits seem to align. It's a particular

[00:12:49] cluster of those objects and so they all you know their orbits are all aligned in one direction.

[00:12:59] Now that's been disputed in more recent papers what has been suggested is that that's just a

[00:13:05] selection effect. We're seeing that because we're only looking at the brighter objects and you know

[00:13:11] if you look at everything or you look at the whole cloud of coca bell objects in orbit around the sun

[00:13:17] beyond Neptune you're going to find that that thing disappears. However the proponents for planet

[00:13:23] nine are confident that they are correct that this curious alignment of the orbits is being

[00:13:32] caused by something that has not yet been been discovered and the suggestion is it's an object

[00:13:39] five to ten times the earth's mass and I think if I remember rightly something like four times the

[00:13:46] diameter of the earth was suggested but that depends on its density of course. So five to ten

[00:13:51] times the mass of the earth is the critical bit and that's led to it being called planet nine

[00:13:58] which is upset some other people who think planet nine is Pluto but yes the international

[00:14:05] astronomical community doesn't think that is the case. Anyway how do you discover

[00:14:13] planet nine? Well looking for it does seem to have worked and part of the reason is that

[00:14:20] the position where it's most likely to be is slap bang in the middle of the Milky Way

[00:14:27] and so it's really it's hidden among gazillions of other stars you're looking for something

[00:14:36] whose distance is I remember rightly thousands of times the distance of the earth from the sun

[00:14:43] so way way out there in the depths of the solar system you have to look for its motion to identify

[00:14:51] that it's not a star and the things at that distance move very very slowly through space

[00:14:58] so this suggestion though comes from Manho Chan who is an associate professor in the

[00:15:06] department of science and environmental studies at the education university of Hong Kong

[00:15:11] has written a paper called what if planet nine has satellites and follows through some of the

[00:15:19] tricks that that might bring for would-be discoverers of planet nine so if you so the theory goes

[00:15:28] if you have satellites of a planet like planet nine as they orbit it if they're in orbits

[00:15:37] that are anything but perfect circles they will be heated by tidal interactions and this is kind

[00:15:45] of what happens to the well particularly EO in orbit around Jupiter that's squeezed and squashed by

[00:15:51] the gravity of Jupiter as it as it orbits and that is why its temperature high is high enough

[00:15:58] to make it the most volcanically active body in the solar system well erupting all the time

[00:16:03] so this same idea if you apply it to planet nine what you've got is essentially heating

[00:16:12] that is variable as the planet goes around sorry as the satellite goes around its planet

[00:16:20] that heating you know it changes oh the temperature of the the satellite changes

[00:16:28] throughout the orbit around its parent body which in this case is the hypothetical planet nine

[00:16:34] that change is something that could be detected and so rather than looking for

[00:16:41] desperately slowly moving objects in the Milky Way what you look for is objects which are changing

[00:16:53] relatively rapidly a heat signature you can put it that way that's that's changing

[00:16:58] more rapidly than what you would expect from any other object in the background it would be a

[00:17:03] variable object and moreover the the author of this paper has pointed out that there is one

[00:17:10] telescope on earth which would be eminently capable of detecting that at this enormous distance

[00:17:16] from earth and that is alwa the Atacama large millimeter some millimeter array up there in

[00:17:23] the heights above san pedro the atacama uh 5000 meters and operated by actually a

[00:17:33] sort of uh it's these three different organizations that operate alma but one of which is the european

[00:17:40] southern observatory which of course is very close to our hearts here in here in australia

[00:17:44] because of that strategic partnership so um he this author is suggesting we should get alma

[00:17:50] onto looking for satellites of planet nine which is an extraordinary idea so um yeah fascinating

[00:17:59] thought except uh what if it's not a planet what if it's a body of smaller objects which is another

[00:18:04] theory as to what might be causing those gravitational effects that's that's right there are a number of

[00:18:09] you know uh planet sized black hole is another one that's been suggested uh so but but um

[00:18:18] even such a weird and wonderful object as that might have satellites that's that's the idea if the if

[00:18:25] the if the planet nine or the planet nine proxy whatever it is is compact enough and has satellites

[00:18:30] around it then the tidal effects will still exist all right so it's just an idea as to how we

[00:18:37] should look that's not actually happening as yet sadly no but uh it might go on the wish list for

[00:18:44] you know planet nine pundits uh and you never know it might happen by that i mean somebody

[00:18:49] might apply for time on alma to do this uh and that could could do the trick the other reason

[00:18:55] it's called planet nine is because when you're asked a question have they found it the answer is nine

[00:19:01] nothing would be in munich where it was last week two weeks in a row we've had to you

[00:19:06] there's a drum gun yes we are we're getting we're getting messages about it as well

[00:19:13] yeah that's right i do all right uh this is Space Nuts with andrew dunkley and professor fred

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[00:21:29] keeping yourself safe Nord VPN dot com slash space nuts now back to the show

[00:21:37] three two one space nuts now we're going to talk about sun rays on mars this has been a

[00:21:45] rather amazing photograph that's been sent back the by the curiosity rave it also dovetails well

[00:21:51] with a photo that was sent to me by rusty and donnie brook of a similar situation looking out

[00:21:59] from his place in western australia and he was asking why the sun sort of split up into rays

[00:22:06] and the answer on earth is dust and and sort of only letting through the rays of red light

[00:22:13] because the dust scattered all the all the other colors in the spectrum

[00:22:17] something to that effect if i'm remember remembering it correctly but it doesn't look the same on mars

[00:22:23] it's a it's a different effect maybe for a reason but a different effect yeah i um so so you're

[00:22:30] right about the you know the the sunlight being read when it's really down on the horizon it's

[00:22:37] partly sometimes it's dust but actually the molecules of the atmosphere also scattered light so the

[00:22:42] blue lights scattered out and we see this predominantly red light now i'm not sure what um rusty was

[00:22:48] sending you but um when when we get this phenomenon uh and it's you know everybody's seen it the

[00:22:57] phenomenon of of light uh sunlight being sort of separated into individual rays by clouds

[00:23:05] blocking our view of the sun uh and you combine that with a dusty atmosphere then you get these

[00:23:11] rays of light the shafts of light that are so obvious at sunset they've got a technical term

[00:23:18] they're called uh preposkular rays uh krepeskul is a french word meaning evening or twilight

[00:23:25] and so uh they're you know they're very common and um i find them fascinating sometimes i've only

[00:23:33] seen this once uh and it was not very far from you where i used to live in terry hills in

[00:23:38] northern sydney i saw those rays going right across the sky all the way from the setting sun on one

[00:23:46] side to the uh the opposite what's called the anti solar point on the other side and occasionally

[00:23:52] you will see that uh and occasionally you'll see what looked like rays uh if you've got

[00:23:58] your back to the sun you can see rays sort of coming out from the point exactly opposite

[00:24:03] the sun and they're called anti solar krepeskula rays and actually there's a picture of them

[00:24:09] taken by marnie uh some years ago in my book cosmic chronicles or what's he called in

[00:24:16] america exploding planets and invisible stars that's right there's a nice color picture

[00:24:22] of those anti solar kreposkula rays and but um so the chase we now have a lovely image

[00:24:29] from curiosity uh the other rover on mars that's still going strong of kreposkula rays

[00:24:36] on mars and it's a phenomenon that has been expected but has never been seen before

[00:24:41] and this is after sunset and so what you've got is these rays of light and they're they're

[00:24:47] blocked into rays by clouds that are blocking the sunlight below the horizon yeah so it turns

[00:24:54] the light instead of being a fan of light it turns it into a you know these individual streaks of light

[00:24:59] but they too are lighting up thin clouds uh in the in the sky above curiosity and that's why

[00:25:07] they show up the kreposkula rays uh i think uh it's something that we might expect down the

[00:25:14] track from somewhere over on mars to see the anti solar kreposkula rays that i've just been

[00:25:18] talking about as these shots of light meet on the other side of the sky uh an effective

[00:25:23] perspective of course the the whole thing is due to perspective because these shafts of light are

[00:25:28] actually parallel uh it's the sun's light is power parallel rays because the sun is so far away

[00:25:35] and as it blocks the as the clouds block blocks bits of it so you get just individual

[00:25:41] shafts of light they look as though they're they're streaming from the sun itself a very

[00:25:46] evocative image but they're actually parallel yeah and yet um being after sunset on mars it's

[00:25:52] it's not the kind of red you see on earth it's um it's a very different um it's yes

[00:25:58] sunsets on mars are blue yeah and that's because um well the the sky the daytime sky on mars is pink

[00:26:07] and the sunset sky is blue and it's the opposite way around from what we expect on earth yeah and

[00:26:12] that's because the dust particles such a large amount of suspended dust in the martian atmosphere

[00:26:18] the dust particles are bigger than uh that this molecules of air that scatter scatter sunlight

[00:26:25] on earth and so there's a different scattering process takes place and that's why you've got

[00:26:30] a pink sky yeah looks amazing um if you want to look at that image it's on the fizz.org website

[00:26:39] it's it's quite uh it's quite pretty i'll say pretty uh and yeah sun rays on mars if you do

[00:26:45] search for that you should be able to find it uh now um to another story jewe jamming it in today

[00:26:51] aren't we uh it's jammies the words yeah um and and it goes back to something that uh we get a lot

[00:26:58] of questions about and i think we got a couple of questions about it last week and that is the

[00:27:02] big bang um now they're saying our universe may have been started by a dark big bang what's

[00:27:10] a dark big bang well it's the suggestion right wasn't it at the beginning or we don't know but

[00:27:17] biblically it was uh it was so the big bang itself was not dark and we know that because we

[00:27:24] still see it here with the in the cosmic microwave background radiation that's the the big bang the

[00:27:31] light of the big bang redshifted to be a thousand or 1500 times longer wavelength than it was when

[00:27:37] when the light left well um this is really uh trying to understand

[00:27:45] how dark matter uh came into being um because the that the current theory suggests that

[00:27:57] uh the big bang uh created spacetime and matter and at first it was just pure energy

[00:28:07] but that pure energy i think when the universe was something like 15 to 20 minutes old

[00:28:14] it it's it kind of condensed into into protons and neutrons in a period which has the technical

[00:28:23] term of the big bang nuclear synthesis and it's that this one of the one of the reasons why we

[00:28:31] believe the big bang because when you do the theory of how this big bang nuclear synthesis would work

[00:28:36] you get exactly the amount of hydrogen helium and some lighter elements uh i can't remember

[00:28:43] what they are actually um it's lithium one i think there is a lithium issue anyway those

[00:28:50] lighter elements uh basically are uh exactly what we find in the universe is what's predicted by

[00:28:57] big bang nuclear synthesis which is one reason why the big bang theory so uh you know it's so

[00:29:02] well established however um what we can't understand is where the dark matter came from

[00:29:09] i mean we don't know what dark matter is we know it's some some form of uh subatomic

[00:29:14] particle um and there's a very good reason for believing that uh but it makes up the majority

[00:29:20] of mass in the universe and so most theories of the big bang assume that that you know whatever

[00:29:28] the process was that generated the particles themselves the the particles that we can uh we

[00:29:35] can uh see or detect also created dark matter and after uh and the dark matter then really didn't do

[00:29:44] much it is just there uh not interacting with anything else but this is a new idea um

[00:29:51] i'm not actually sure it's kathryn freezes the lead author on this paper i'm not quite

[00:29:58] sure where kathryn's based um but that new idea that this due to kathryn and her colleagues it argues that

[00:30:08] there was a different formation of dark matter particles so uh the the dark matter didn't

[00:30:22] condense into particles at the same time as the the visible matter uh it was it was left as a sort of

[00:30:31] radiation field within the the early universe um that took longer to uh basically flop out into

[00:30:42] dark matter particles than the protons and neutrons did they did it within the first 20 minutes

[00:30:48] or so but the suggestion is that this radiation field that eventually became dark matter took longer

[00:30:57] to to um to turn from a radiation field into into subatomic particles even though they're

[00:31:06] invisible to us and and the reason why that's um that is useful in trying to work out what happened

[00:31:13] was that it essentially separates the evolution of normal matter from the evolution of dark matter

[00:31:23] and uh that kind of lets you concentrate on the the way normal matter came into being which we

[00:31:30] think we understand very well but perhaps opens up new ways that we could look at the models of

[00:31:37] dark matter if it if it had a completely separate evolution from from the the normal matter i'm not

[00:31:45] sure i'm explaining this very well but it is actually a really nice idea and the team uh is

[00:31:52] i think give it the team that's doing this research is giving the uh as coined the term a dark big

[00:31:58] bang um they have put a limit on it a time limit that dark big bang had to happen uh before the

[00:32:06] universe reached the age of one month no so sometime within the first month you got the dark

[00:32:13] big bang okay now i did look up kathryn she's got her own website good and it says here on her website

[00:32:22] that she is the george e allen beck professor of physics at the university of michigan there you go

[00:32:28] thank you for that thank you um there's there's one other consequence of this uh that um we might

[00:32:35] just mentioned before we turn it to pumpkins uh he um that they suggest that uh that dark big bang

[00:32:44] would actually uh generate very strong gravitational waves that might be detected in today's universe

[00:32:52] and so uh they are concentrating on gravitational wave detection as being perhaps one way of

[00:32:59] investigating this further that's unerding i love this stuff isn't it it's great yeah it is uh well

[00:33:05] well as i keep saying we will crack it one day we will figure it out and indeed we will we hopefully

[00:33:12] tomorrow um probably will be you'll be but maybe not all right uh this is space nuts with

[00:33:20] andrew dunkley and professor fred what's on okay we checked all four systems and seeing with the girls

[00:33:28] space nuts all right fred uh we turn it over to the audience or we turn our attention to the

[00:33:34] audience as they come up with some questions for us and our first one today is from peter

[00:33:42] and it's a subject we've never talked about before except for last week and maybe the week before

[00:33:48] hello fred and andrew this is peter from belgium i was just listening into the last episode

[00:33:55] and just thinking of a thought experiment if traveling faster than speed of light allows

[00:34:01] you to travel backwards in time from an outside point of view imagine that you have an observer

[00:34:08] from earth would you need to be traveling twice the speed of speed of light

[00:34:18] to actually travel backwards and in time at just at the same rate but then in reverse on how

[00:34:28] we currently perceive time on earth and so to travel faster back in time you would just have

[00:34:35] to travel like three times the speed of light is this like a linear equation or do are we talking

[00:34:42] about exponential or another form of relation thank you very much and uh love the show looking

[00:34:49] forward to the new episode every time thank you peter uh fast but then light question yet

[00:34:55] again we get a few of those uh so if you travel faster than the speed of light which you can't

[00:35:00] do but if you could the theory is that time would go backwards but if you traveled faster and faster

[00:35:07] like one two three four five ten times the speed of light would you travel back in time faster

[00:35:16] so this is um it's kind of tachyon theory is this yes t a c h y o n rather than t a t ac k

[00:35:26] why are you ahead it's not that tacky it's uh it's uh tachyons are hypothetical particles

[00:35:33] able to travel faster than the speed of light now as far as we know they don't exist because

[00:35:38] relativity is quite firm on the view that to accelerate anything to the speed of light

[00:35:44] except light itself uh you have to provide infinite energy and that tends to be a show stop

[00:35:49] infinite energy is not something we have uh even today where energy is a lot easier to come by

[00:35:57] than it used to be unless unless you're in europe um so the um the uh the the idea of tachyons uh

[00:36:06] exactly as peter says is that you will get the phenomenon that from the tachyon's point of

[00:36:13] time is traveling backwards um now uh i think actually what peter's hypothesized is probably

[00:36:22] right that the the faster you travel the quicker you go backwards in time it would definitely not be a

[00:36:29] linear relationship because nothing in relativity is linear that everything's usually multiplied or

[00:36:36] divided by a factor of the square root of one minus v squared over c squared that's the bit

[00:36:42] that always comes into uh relativity equations at least special relativity equations uh and that's

[00:36:48] that's for example why uh if you uh it just to um put it back to something that really does happen

[00:36:56] if you are on an object moving at close to the speed of light if you're on a spacecraft

[00:37:02] and you point a torch out ahead of you uh and shine the torch beam ahead of you uh those

[00:37:08] to your velocity and the and the speed of light from the torch don't just add because if they did

[00:37:14] they would give you a they'd exceed the speed of light uh there's something called relativistic

[00:37:19] addition of velocities you can look it up on the web and it once again it's called that

[00:37:25] one minus v squared over c squared thrown in there that that actually means that you never

[00:37:30] achieved the speed of light so the velocity addition uh has uh you know it's not like

[00:37:36] normal arithmetic and the same will be true uh in terms of tachyons i've never really looked at

[00:37:42] tachyon theory uh i probably should do should that since we get to talk about it quite a lot

[00:37:48] have a look at the equations and see what they look like but i can i can imagine already what

[00:37:53] they look like just because all relativistic equations have got so great question peter

[00:37:59] and thank you for thinking along those lines hmm so the answer was yes could have done that

[00:38:05] yes ish yeah yes ish yes maybe yes so they're not linear there's that's that's the one thing i can't say

[00:38:11] but definitely it's not a linear addition okay thank you peter now i'm going to swipe this question

[00:38:17] over and put it on your face because i need to read it in front of me and this one comes from

[00:38:23] Gavin in yes in New South Wales which is near our national capital of Canberra uh i have a

[00:38:29] question for he's got two questions so we'll do them one at a time i have a question for

[00:38:33] dr fred regarding a topic seldom mentioned here space uh it appears from photos etc that all matter has

[00:38:40] an angular momentum which appears to be anti-clockwise except venus as all matter was formed from the

[00:38:46] big bang a bang i assume that the big bang also has angular momentum if space was also formed

[00:38:54] in the big bang it seems logical that space also has angular momentum if you think of a bicycle

[00:38:59] wheel the hub rotates at a slower speed than the rim this means that further out you look from the

[00:39:05] hub the faster the wheel is turning if the big bang center is everywhere we are the hub same

[00:39:13] applies to distant galaxies oh what do you think of that idea fred um so we don't know if the

[00:39:24] universe the universe has angular momentum what we do know and uh gavin's correct uh

[00:39:30] certainly in the solar system most things revolve anti-clockwise as seen from above the earth's north

[00:39:37] pole and that's because the cloud of gas and dust that formed the planets and the sun uh

[00:39:43] actually was rotating and the the sort of theory is that uh these giant gas clouds that form

[00:39:51] solar systems um they collapse and in them you get little worlds and eddies being formed

[00:40:00] and it's those eddies that gradually build up to give you a preferred rotational direction and

[00:40:05] that's what imparts as it collapses the energy of the collapse goes into imparting rotation

[00:40:10] to the planets so well first of all the protoplanetary disk and then in turn the

[00:40:15] planets which are formed within that disk so uh that's how solar systems work in terms of their

[00:40:23] rotation and galaxies are probably somewhat similar uh that you start off with gigantic

[00:40:28] clouds in the early universe that collapse under their own gravity and begin rotating um

[00:40:35] and so you know there's there's the angular point I'm trying to make is that the angular

[00:40:40] momentum of objects within the universe comes from processes separate from the big bang there

[00:40:46] they are physical processes that take place in the normal course of events of the universe

[00:40:51] so in terms of the universe itself we don't have any way of detecting whether it's rotation

[00:40:59] or whether it's rotating and if it was what frame of reference would it be rotating in

[00:41:05] because um by you know the definition of the universe is everything we can see or detect

[00:41:12] and that doesn't allow for multiverses which is a different idea but in the normal definition

[00:41:18] of a universe you wouldn't you wouldn't be able to tell only if there are multiverses would you

[00:41:23] perhaps be able to work out that there is some higher order reference frame within which you

[00:41:29] against which you could measure the rotation of the universe okay have we found any galaxies that are

[00:41:36] rotating in the opposite direction to what we would consider normal yes um only only in the sense that

[00:41:44] for example spiral galaxies uh uh almost always are rotating with the spiral arms

[00:41:52] trailing uh and that so that would be what you call the normal rotation direction there is

[00:41:57] at least one that is completely counterintuitive it's rotating in the opposite direction from

[00:42:05] this spiral arm trailing model the kind of what it's called but uh generally galaxies behave well

[00:42:13] I should explain though that you know you you don't really know the difference between clockwise

[00:42:18] and anticlockwise when it comes to galaxies because they're all at completely random angles

[00:42:24] there are some indications of alignments along the filaments of the cosmic web which is that sort of

[00:42:32] background scaffolding structure that we think is what gave rise to the

[00:42:35] the large-scale structure in the universe I think there are some ideas of alignments of rotation

[00:42:40] along for galaxies along those uh filaments of the cosmic web but yeah looked at that recently

[00:42:47] but in general terms galaxy rotations are pretty rudder okay now peter has a second question

[00:42:56] and he said um recently either the james web or Hubble telescopes found a gravitational lens the

[00:43:03] lens had three images of a distant galaxy it was observed that a supernova occurred in the galaxy

[00:43:09] and the scientists were able to watch the supernova at three different times i.e the images

[00:43:15] must have traveled various distances through space due to the curvature of space around the lens

[00:43:21] if we have a black hole or neutron star merger which creates a gravitational wave in that distant

[00:43:27] galaxy would we detect three gravitational waves i.e one from each image or would we see only the one

[00:43:35] I feel it would have could uh that it would confirm that space bends

[00:43:39] uh or light bends one or the other uh yes I'm gonna call them from a paper

[00:43:50] paper in astronomy and astrophysics the main european journal for astronomy i'm going to quote

[00:43:55] from that uh the quote is as follows when gravitational waves propagate near massive

[00:44:00] astrophysical objects their trajectories will curve resulting in gravitational

[00:44:05] lensing and multiple images as well as we observe the waves from each multiple image their

[00:44:10] amplitudes will have changed because of the focusing by lensing so uh the bottom line is yes

[00:44:17] gravitational waves behave like lines when it comes to uh comes to gravitational lensing

[00:44:22] which means that yes you might see multiple uh uh detections of gravitational waves from

[00:44:29] the same object uh if it's lensed by an intervening galaxy or cluster of galaxies for example

[00:44:35] so there you go great question yeah so yes the answer is three times g w rather than one

[00:44:41] times g jump g w which was Gavin's yes little um abbreviation for yeah yeah that's right okay so

[00:44:49] three times g w Gavin that would have been there all right thanks for your question thanks also to

[00:44:55] peter if you have questions for us of course we'd love to hear from you you can jump on our

[00:45:00] website and click on the AMA link and send us a text or audio question that way or you can

[00:45:06] click on the send us your voice message on the right hand side which just sits there regardless

[00:45:12] of which page you're on and it's easy you know if you've got a device with a microphone that's

[00:45:18] as simple as just pushing the button and saying hi i'm fred from sydney and i have a question

[00:45:24] about muskats or whatever but uh yes that's as easy as it gets and while you're on our website

[00:45:33] have a browse around check out astronomy daily check out the shop check out ways of supporting us if

[00:45:38] you so desire through um various means it's all available on our website and uh yeah pretty easy

[00:45:46] um fred uh i don't forget social media uh lots of people are very very active on the

[00:45:52] space nuts podcast group on facebook and it's a lot of fun too um i shamelessly posted a

[00:45:59] link to my ebooks being on sale for the next couple of weeks just in case you want you know

[00:46:05] just in case well fred got your plug yeah sorry yep yeah anyway uh it's a it's a good fun site

[00:46:13] we're done for another week fred thank you so much it's a pleasure and great to be back

[00:46:19] in uh one is a really very special country it is it's not there we're shrouded in smoke here at the

[00:46:26] moment we've seen she will be yeah you got fires down man yeah big big hot windy dry day last week

[00:46:33] you know we got a big fire south of the city it's still burning but they've got it

[00:46:38] almost under control yeah i love the wording they use at the rural fire service around here

[00:46:42] if it's not under control it's being controlled okay it's good smart well good all right yeah

[00:46:50] yeah we could see it the grandchildren thought it was amazing they thought it was a cloud but it

[00:46:54] wasn't it was smoke deaths um till next week fred thank you so much we'll see you soon

[00:46:59] sounds great thanks andrew fred what's an astronomer at large part of the team here at

[00:47:04] space nuts and thanks to hu back in the studio it's not a studio it's actually a smoking

[00:47:09] room or something that is inverted into you know a man cave um and from me andrew duckley thanks for

[00:47:16] your company we look forward to joining you again next time on another edition of space nuts bye bye

[00:47:39] this has been another quality podcast production from fights.com