00:00:00 --> 00:00:02 Hi there. This is Space Nuts Q&A. My
00:00:02 --> 00:00:04 name is Andrew Dunley. Great to have
00:00:04 --> 00:00:05 your company. Coming up on this episode,
00:00:05 --> 00:00:08 we'll answer questions from Steve, Gus,
00:00:08 --> 00:00:10 and Nick. Uh Steve and Gus are sort of
00:00:10 --> 00:00:13 focused on the same thing, gravity.
00:00:13 --> 00:00:15 Steve wants to know if it can exist
00:00:16 --> 00:00:18 without mass. Uh and and Gus is talking
00:00:18 --> 00:00:21 about gravity and energy, and what's the
00:00:21 --> 00:00:24 relationship? And Nick is asking about
00:00:24 --> 00:00:26 galaxy movements, and are any moving
00:00:26 --> 00:00:29 towards us that we can't see yet?
00:00:29 --> 00:00:31 Well, we don't know. We can't see them
00:00:31 --> 00:00:33 yet. Uh, but we'll see if we can tackle
00:00:33 --> 00:00:36 all of that on this episode of Space
00:00:36 --> 00:00:36 Nuts.
00:00:36 --> 00:00:41 >> 15 seconds. Guidance is internal. 10 9
00:00:41 --> 00:00:43 Ignition sequence start.
00:00:43 --> 00:00:44 >> Space nuts.
00:00:44 --> 00:00:46 >> 5 4 3 2
00:00:46 --> 00:00:49 >> 1 2 3 4 5 5 4 3 2 1
00:00:49 --> 00:00:50 >> Space Nuts.
00:00:50 --> 00:00:52 >> Astronauts report. It feels good.
00:00:52 --> 00:00:55 >> Here he is again. Professor Fred Watson.
00:00:55 --> 00:00:58 Hello, Fred. Hello, Andrew. Hello. How
00:00:58 --> 00:01:00 are you doing now?
00:01:00 --> 00:01:04 >> I'm doing the same as I was before.
00:01:04 --> 00:01:05 >> How about you?
00:01:05 --> 00:01:07 >> Uh, well, I'm I'm still doing the same
00:01:07 --> 00:01:10 as I was before. Yes, that's right. And
00:01:10 --> 00:01:11 I hope to be doing the same again very
00:01:11 --> 00:01:12 soon.
00:01:12 --> 00:01:17 >> Yes, indeed. Yes. Shall we just sort of
00:01:17 --> 00:01:19 muck in and get these questions sorted
00:01:19 --> 00:01:23 out? I I it was a like a couple of weeks
00:01:23 --> 00:01:26 ago we we had um gravity questions
00:01:26 --> 00:01:28 coming in thick and fast. Uh no black
00:01:28 --> 00:01:30 hole questions but today it's gravity
00:01:30 --> 00:01:31 questions this
00:01:31 --> 00:01:34 >> and our first our first one comes from
00:01:34 --> 00:01:35 Steve.
00:01:35 --> 00:01:38 >> Hi guys, my name is Steve. I'm uh from
00:01:38 --> 00:01:43 New Zealand. Um really enjoy your show.
00:01:43 --> 00:01:46 recently read a article
00:01:46 --> 00:01:50 implying that uh gravity could be
00:01:50 --> 00:01:53 possible without mass
00:01:53 --> 00:01:57 and um I'm wondering if that would be uh
00:01:57 --> 00:02:02 another alternative explanation uh to um
00:02:02 --> 00:02:07 uh to dark matter and to uh Mond.
00:02:07 --> 00:02:09 Yeah, I don't know if that makes it very
00:02:09 --> 00:02:11 clear to you. Anyway, thanks. All right.
00:02:11 --> 00:02:13 Uh Steve, thanks for the question.
00:02:13 --> 00:02:17 Gravity without mass. Well, I doubt that
00:02:17 --> 00:02:19 uh we can turn to the Catholic Church
00:02:19 --> 00:02:22 because they do they do have mass. Um
00:02:22 --> 00:02:24 but
00:02:24 --> 00:02:27 [Music]
00:02:27 --> 00:02:28 terrible. Uh it's an interesting
00:02:28 --> 00:02:33 question though. It is. And um so yeah,
00:02:33 --> 00:02:36 my reading on this, excuse me, is is
00:02:36 --> 00:02:41 yes. Um that's correct. So, uh, actually
00:02:41 --> 00:02:43 there's a nice thread about this on
00:02:43 --> 00:02:46 Reddit if anybody looks at that website.
00:02:46 --> 00:02:49 >> I do. And, uh, well, I love Reddit.
00:02:49 --> 00:02:52 >> Yeah.
00:02:52 --> 00:02:54 I'm really, well, I do remember my, uh,
00:02:54 --> 00:02:56 one of my sons was an absolute Reddit
00:02:56 --> 00:03:00 fiend at one time. He was very much um,
00:03:00 --> 00:03:04 a Reddit fan. Uh, now, so that's how I
00:03:04 --> 00:03:05 was aware of it. But um, but I haven't
00:03:06 --> 00:03:08 been a great user of Reddit. But the
00:03:08 --> 00:03:11 bottom line, excuse me, is
00:03:11 --> 00:03:15 um and and this is the way is phrased in
00:03:15 --> 00:03:18 this particular conversation. If you
00:03:18 --> 00:03:20 increase the temperature
00:03:20 --> 00:03:24 of an object and they take a planet in
00:03:24 --> 00:03:27 this case uh and in fact I might just
00:03:27 --> 00:03:30 read it uh because this kind of is quite
00:03:30 --> 00:03:32 interesting.
00:03:32 --> 00:03:34 and
00:03:34 --> 00:03:36 take your Neptune you take your
00:03:36 --> 00:03:38 Neptunian planet something the size of
00:03:38 --> 00:03:40 Neptune raise the temperature by 300°
00:03:40 --> 00:03:43 Kelvin instantly now the mass of Neptune
00:03:44 --> 00:03:47 is about 10 26 kg and if we roughly
00:03:47 --> 00:03:49 assume all its hydrogen uh uh
00:03:49 --> 00:03:53 corresponds to about 6 * 10 52 particles
00:03:53 --> 00:03:56 of hydrogen uh it's the thermal energy
00:03:56 --> 00:03:59 is roughly given by an equation there E=
00:03:59 --> 00:04:01 NT
00:04:01 --> 00:04:03 uh uh which leads to an increase in
00:04:03 --> 00:04:06 thermal energy
00:04:06 --> 00:04:10 uh of da d and it's a large number of
00:04:10 --> 00:04:13 jewels um actually it's a small number
00:04:13 --> 00:04:18 of jewels it's k * 6 * 10 - 52 * 300
00:04:18 --> 00:04:20 jewels
00:04:20 --> 00:04:24 uh which um if you then convert that so
00:04:24 --> 00:04:26 so what what this is saying is you you
00:04:26 --> 00:04:29 you warm up a planet you get an increase
00:04:29 --> 00:04:32 uh in the thermal energy of that planet.
00:04:32 --> 00:04:35 You can then use E= MC² to convert that
00:04:35 --> 00:04:38 thermal energy into mass and in this
00:04:38 --> 00:04:40 case it comes out to be something like 3
00:04:40 --> 00:04:47 * 10 15 kg which is a lot but uh is not
00:04:47 --> 00:04:49 very much in comparison with a planet.
00:04:49 --> 00:04:53 Uh but that does mean that adding energy
00:04:53 --> 00:04:55 to something will increase its
00:04:55 --> 00:05:00 gravitational mass. Now um the Steve's
00:05:00 --> 00:05:04 sort of uh you know um next step in the
00:05:04 --> 00:05:06 argument from that is whether that could
00:05:06 --> 00:05:08 be misleading us in the idea of dark
00:05:08 --> 00:05:13 matter and things of that sort. Um and
00:05:13 --> 00:05:15 uh I I can't really get my head around
00:05:15 --> 00:05:18 how that would work. Um he mentioned M
00:05:18 --> 00:05:21 as well the modified Newtonian dynamics.
00:05:21 --> 00:05:25 Uh because my understanding is that
00:05:25 --> 00:05:28 everybody who looks at these
00:05:28 --> 00:05:30 particular problems what is dark matter?
00:05:30 --> 00:05:32 What is dark energy? They take into
00:05:32 --> 00:05:35 account everything. Uh I've read some of
00:05:35 --> 00:05:39 the papers on this. And so things like
00:05:39 --> 00:05:41 um you know gravitational
00:05:41 --> 00:05:45 uh gravitational influence of of pure
00:05:45 --> 00:05:47 energy and in this case we're talking
00:05:47 --> 00:05:52 about heat energy. Uh that uh is likely
00:05:52 --> 00:05:54 to be something that would be already in
00:05:54 --> 00:05:56 the equations. Um so I don't think it's
00:05:56 --> 00:05:58 the answer but it's a really interesting
00:05:58 --> 00:06:00 suggestion and an interesting thing to
00:06:00 --> 00:06:03 think about. Uh so thank you very much
00:06:03 --> 00:06:04 Steve.
00:06:04 --> 00:06:07 >> Yeah indeed. um just made me wonder, are
00:06:07 --> 00:06:09 we increasing Earth's gravity because
00:06:09 --> 00:06:11 we're heating the planet up?
00:06:11 --> 00:06:15 >> Yep, that's probably right. Um that I
00:06:15 --> 00:06:17 mean the the example that uh I just read
00:06:17 --> 00:06:20 out was about three t 300
00:06:20 --> 00:06:23 300° Kelvin, an instant uh increase in
00:06:24 --> 00:06:26 that. We're talking about one or two
00:06:26 --> 00:06:29 degrees Kelvin. uh but uh which makes a
00:06:29 --> 00:06:31 big difference to the earth's atmosphere
00:06:31 --> 00:06:32 but probably not that much difference to
00:06:32 --> 00:06:36 its uh you know gravitational potential.
00:06:36 --> 00:06:38 M okay. So the answer is yes. Gravity
00:06:38 --> 00:06:42 can exist without mass but it's probably
00:06:42 --> 00:06:46 not a major factor. Is that fair enough?
00:06:46 --> 00:06:50 >> Uh yes that is right. Um I just been
00:06:50 --> 00:06:52 dragging through my memory Andrew
00:06:52 --> 00:06:55 something else that's sort of vaguely
00:06:55 --> 00:06:59 related to this. Um which is the and we
00:06:59 --> 00:07:01 haven't used this name but we did talk
00:07:01 --> 00:07:04 about it a while ago the cougal blitz.
00:07:04 --> 00:07:06 And do you know what a cougall blitz is?
00:07:06 --> 00:07:10 >> Uh look, I've heard this before. Uh no,
00:07:10 --> 00:07:11 remind me.
00:07:11 --> 00:07:15 >> Yeah. So it's it basically is uh a black
00:07:15 --> 00:07:18 hole made of light. Uh it's and
00:07:18 --> 00:07:20 Wikipedia says it's a concentration of
00:07:20 --> 00:07:22 heat, light, or radiation so intense
00:07:22 --> 00:07:24 that its energy forms an event horizon
00:07:24 --> 00:07:26 and becomes selftrapped. In other words,
00:07:26 --> 00:07:28 if enough radiation is aimed into a
00:07:28 --> 00:07:31 region of space, the concentration of
00:07:31 --> 00:07:33 energy can walk spaceime so much that it
00:07:33 --> 00:07:36 creates a black hole. It's a black hole.
00:07:36 --> 00:07:39 It is a black hole whose original mass
00:07:39 --> 00:07:41 energy was in the form of radiant energy
00:07:41 --> 00:07:43 rather than matter.
00:07:43 --> 00:07:46 Uh now um there is a paper that was
00:07:46 --> 00:07:49 published in
00:07:49 --> 00:07:50
00:07:50 --> 00:07:53 that concludes that a phenomenon like
00:07:53 --> 00:07:55 this cannot occur in any realistic
00:07:55 --> 00:07:58 scenario within our universe. So cougal
00:07:58 --> 00:08:01 blitzes are a theoretical entity that
00:08:01 --> 00:08:04 are not are thought not to occur in
00:08:04 --> 00:08:07 nature. Uh but it is a similar thing
00:08:07 --> 00:08:09 isn't it? It's a it basically it's a
00:08:09 --> 00:08:11 it's a black hole made of energy.
00:08:11 --> 00:08:14 >> Yeah. Wow, that's really interesting. I
00:08:14 --> 00:08:15 tell you something else that does exist
00:08:15 --> 00:08:19 is a Google Scriber. So, so
00:08:19 --> 00:08:22 I've got one of those. Have you?
00:08:22 --> 00:08:24 >> Yeah, there it is.
00:08:24 --> 00:08:26 >> It's a pen. It's German.
00:08:26 --> 00:08:28 >> Hold it up. Ah, okay.
00:08:28 --> 00:08:29 >> Cougle scriber.
00:08:29 --> 00:08:31 >> A cougriber.
00:08:31 --> 00:08:32 >> Yes.
00:08:32 --> 00:08:33 >> Do you know what German is? You know
00:08:33 --> 00:08:35 what the German is for pencil?
00:08:35 --> 00:08:37 >> Uh, I probably did once, but I don't
00:08:37 --> 00:08:38 now. That's
00:08:38 --> 00:08:41 >> bliff blift.
00:08:41 --> 00:08:42 >> All right.
00:08:42 --> 00:08:44 >> It's probably
00:08:44 --> 00:08:47 I only I did languages at high school
00:08:47 --> 00:08:48 and I was very good at them and I should
00:08:48 --> 00:08:50 have probably pursued that somewhere
00:08:50 --> 00:08:52 along the line, but German stuck with
00:08:52 --> 00:08:55 me. I some of the references I still
00:08:55 --> 00:08:57 remember today. Someone's going to
00:08:57 --> 00:08:58 correct me now because I'd probably
00:08:58 --> 00:09:01 bugger it up the pronunciation.
00:09:01 --> 00:09:02 >> Anyway,
00:09:02 --> 00:09:03 >> that's all right.
00:09:03 --> 00:09:04 >> I'm just showing off now. No, it's a
00:09:04 --> 00:09:07 it's a side of your character that I was
00:09:07 --> 00:09:11 unaware of. Um, Andrew, I um, curiously,
00:09:11 --> 00:09:14 I uh never joined never joined Lurman at
00:09:14 --> 00:09:17 school. I never learned German at
00:09:17 --> 00:09:22 school. Um, but, uh, uh, when I was 14,
00:09:22 --> 00:09:25 uh, I went on a school exchange to
00:09:25 --> 00:09:27 Germany, which was bar because I wasn't
00:09:27 --> 00:09:29 studying German, but that that was my
00:09:29 --> 00:09:31 first overseas visit, of course, from
00:09:31 --> 00:09:34 the United Kingdom. Um, and so I've
00:09:34 --> 00:09:38 spent the the however many years it is,
00:09:38 --> 00:09:41 60 odd years since then, trying to learn
00:09:41 --> 00:09:43 German.
00:09:43 --> 00:09:45 And um, yeah.
00:09:45 --> 00:09:48 >> Yeah. Look, I'm so jealous of students
00:09:48 --> 00:09:50 in countries like the United States and
00:09:50 --> 00:09:53 the UK and Europe because they get to do
00:09:53 --> 00:09:55 excursions to other countries. In
00:09:55 --> 00:09:57 Australia, we got to do excursions to
00:09:57 --> 00:10:02 Sydney and Canra. I mean, come on.
00:10:02 --> 00:10:03 That was it.
00:10:03 --> 00:10:04 >> Yeah,
00:10:04 --> 00:10:06 >> that was as good as it got for us.
00:10:06 --> 00:10:06 >> Yeah.
00:10:06 --> 00:10:08 >> I mean, these days they get to go to New
00:10:08 --> 00:10:11 Zealand once in a while. Um, but yeah,
00:10:11 --> 00:10:13 we we're so far from everywhere, it's
00:10:13 --> 00:10:15 just not easy. Although, my son did go
00:10:15 --> 00:10:17 to go get to do a couple of weeks in
00:10:17 --> 00:10:19 Japan through high school. So,
00:10:19 --> 00:10:19 >> there you go.
00:10:19 --> 00:10:21 >> There are a few options these days.
00:10:22 --> 00:10:23 >> This is Space Nuts. Andrew Dunley here
00:10:23 --> 00:10:28 with Professor Fred Watson.
00:10:28 --> 00:10:31 >> Three, two, one.
00:10:31 --> 00:10:33 Space nuts.
00:10:33 --> 00:10:34 >> Uh, we better keep moving. Uh, thank
00:10:34 --> 00:10:37 you, Steve. Let's get a question from
00:10:37 --> 00:10:38 Gus.
00:10:38 --> 00:10:42 >> Hello, Professor Fred and, uh, Andrew.
00:10:42 --> 00:10:44 This is Gus Iverson from Isiqua,
00:10:44 --> 00:10:46 Washington. I sent in a question for you
00:10:46 --> 00:10:47 guys previously, and you thought I was
00:10:47 --> 00:10:50 in Western Western Australia.
00:10:50 --> 00:10:53 >> Yes. I I've been thinking about uh uh
00:10:53 --> 00:10:57 gravity uh today and it it came to my
00:10:57 --> 00:11:01 mind that if uh energy and mass are
00:11:01 --> 00:11:05 equivalent then essentially uh shouldn't
00:11:05 --> 00:11:09 energy also create gravity at some
00:11:09 --> 00:11:11 level.
00:11:11 --> 00:11:14 Um I'm not sure if this is a related
00:11:14 --> 00:11:17 question or or an extension or or a
00:11:17 --> 00:11:19 separate question though. Um uh
00:11:19 --> 00:11:21 additionally
00:11:21 --> 00:11:25 um if a body of of any size is
00:11:25 --> 00:11:29 generating uh or has mass and it is
00:11:29 --> 00:11:33 generating a gravitational field,
00:11:33 --> 00:11:37 does not that field itself
00:11:37 --> 00:11:41 have energy and mass? And would that
00:11:41 --> 00:11:46 field not create additional gravity by
00:11:46 --> 00:11:48 its simple existence?
00:11:48 --> 00:11:53 So, if that's the case, or even kind of
00:11:53 --> 00:11:55 the case, my question is where does the
00:11:55 --> 00:12:00 energy and mass go if if um or
00:12:00 --> 00:12:03 uh I I I have no idea where to go with
00:12:04 --> 00:12:06 this. Thank you. Uh I love love the show
00:12:06 --> 00:12:08 and appreciate being able to ask
00:12:08 --> 00:12:09 questions.
00:12:09 --> 00:12:11 >> Thank you, Gus. Uh that sounded very
00:12:11 --> 00:12:14 much like something from Catch 22. Yeah.
00:12:14 --> 00:12:16 Was it was it apples or tomatoes? They
00:12:16 --> 00:12:20 were trying to I don't know. Um but uh
00:12:20 --> 00:12:22 yeah, it sounded a bit like that. Um
00:12:22 --> 00:12:25 gravity plus energy. Body plus mass plus
00:12:25 --> 00:12:28 gravity equals energy. But then does
00:12:28 --> 00:12:31 that add mass which adds to gravity? I
00:12:31 --> 00:12:32 think that's what he was trying to
00:12:32 --> 00:12:35 >> Yeah, that's right. So So you've got to
00:12:35 --> 00:12:37 you know the whole thing gets completely
00:12:37 --> 00:12:39 out of hand cuz everything's got
00:12:39 --> 00:12:42 gravity. Um I think uh so the first part
00:12:42 --> 00:12:44 of what Gus was saying is what we've
00:12:44 --> 00:12:46 just been talking about. You know if you
00:12:46 --> 00:12:49 put it into energy and mass
00:12:49 --> 00:12:52 >> um and
00:12:52 --> 00:12:55 gravitation you got be I probably have
00:12:55 --> 00:12:57 to be careful with the words
00:12:57 --> 00:13:01 gravitational gravitation is a potential
00:13:01 --> 00:13:03 uh an object in a gravitational field
00:13:03 --> 00:13:05 has potential energy. So, it does have
00:13:05 --> 00:13:10 energy. Uh, but it I I kind of need to
00:13:10 --> 00:13:12 take this one and notice. Actually, you
00:13:12 --> 00:13:14 did give me notice, Andrew, but I didn't
00:13:14 --> 00:13:16 have time to really look further into
00:13:16 --> 00:13:19 it. But I think um I think there's a I
00:13:20 --> 00:13:21 think there's a stumbling block
00:13:21 --> 00:13:23 somewhere in that argument. Uh, which is
00:13:23 --> 00:13:25 probably that gravitational energy isn't
00:13:25 --> 00:13:29 energy that's convertible to mass. Um,
00:13:29 --> 00:13:32 but I need to get my thoughts clearer on
00:13:32 --> 00:13:34 that, which they aren't at the moment.
00:13:34 --> 00:13:37 So Gus, thank you for a very uh tricky
00:13:37 --> 00:13:40 question uh which um I might think a
00:13:40 --> 00:13:43 little bit more about uh and
00:13:43 --> 00:13:46 >> uh perhaps we will revisit it in a
00:13:46 --> 00:13:49 future episode of Space Notes Q&A.
00:13:49 --> 00:13:52 >> I put a um I put a homework marker next
00:13:52 --> 00:13:53 to it.
00:13:53 --> 00:13:55 >> That's what I'm I'm just doing that. I'm
00:13:55 --> 00:13:57 doing it. You're doing it in your
00:13:57 --> 00:13:59 cougal.
00:13:59 --> 00:14:02 I'm using a red a red cougal scriber.
00:14:02 --> 00:14:03 Okay.
00:14:03 --> 00:14:05 I don't know what the German word for
00:14:05 --> 00:14:06 red is though.
00:14:06 --> 00:14:10 >> Oh, probably do it on translator.
00:14:10 --> 00:14:11 >> There you are.
00:14:11 --> 00:14:13 >> Yeah, there you are. I don't have to
00:14:13 --> 00:14:13 look it up.
00:14:13 --> 00:14:14 >> You don't.
00:14:14 --> 00:14:15 >> Um,
00:14:15 --> 00:14:19 >> so Gus, um, don't know. We don't know.
00:14:19 --> 00:14:22 Maybe, possibly. Could be. Don't know.
00:14:22 --> 00:14:23 >> There's the answer.
00:14:23 --> 00:14:23 >> Don't yet.
00:14:23 --> 00:14:24 >> How's that?
00:14:24 --> 00:14:28 >> Don't don't yet know.
00:14:28 --> 00:14:29 >> I like that.
00:14:29 --> 00:14:29 >> Yeah.
00:14:30 --> 00:14:32 >> Uh, let's um get to the final question.
00:14:32 --> 00:14:35 We'll get back to you Gus at some stage
00:14:35 --> 00:14:37 in Western Australia or it could be the
00:14:37 --> 00:14:39 United States. Uh now we've got a
00:14:39 --> 00:14:42 question from oh um just by coincidence
00:14:42 --> 00:14:46 from New Zealand again. Um hi team
00:14:46 --> 00:14:47 amazing podcast. Which one are you
00:14:47 --> 00:14:50 talking about now? Uh I have been
00:14:50 --> 00:14:51 listening since your early days and I've
00:14:52 --> 00:14:54 always uh looked forward to new uh
00:14:54 --> 00:14:56 uploads. My question is around the
00:14:56 --> 00:14:57 discovery of early galaxies from the
00:14:57 --> 00:14:59 James Webb Space Telescope. Is it
00:14:59 --> 00:15:02 possible for earlier galaxies to be
00:15:02 --> 00:15:04 traveling towards us that are currently
00:15:04 --> 00:15:07 out of reach? Uh filling with uh
00:15:07 --> 00:15:11 potentially nothing uh uh filling where
00:15:11 --> 00:15:13 potentially nothing was in view before.
00:15:13 --> 00:15:15 Uh if possible, would the light be
00:15:16 --> 00:15:17 compressed? How would the instruments
00:15:17 --> 00:15:20 deal with that? Hope that makes sense.
00:15:20 --> 00:15:25 Cheers, Nick from Oakland, New Zealand.
00:15:25 --> 00:15:27 Now, my brain just went, well, I suppose
00:15:27 --> 00:15:29 it's possible, but how do we prove it?
00:15:29 --> 00:15:30 until it happens.
00:15:30 --> 00:15:32 >> Yes. So, uh, couple of things in here.
00:15:32 --> 00:15:35 Um, thanks Nick. Great question. The
00:15:35 --> 00:15:38 last bit about light being compressed.
00:15:38 --> 00:15:41 So, um, and in a way that's, you know,
00:15:41 --> 00:15:43 that's, um, quite a nice way of putting
00:15:43 --> 00:15:45 it. So, anything that comes toward you
00:15:45 --> 00:15:47 that's emitting light, it's light will
00:15:47 --> 00:15:49 be blue shifted. In other words,
00:15:49 --> 00:15:52 >> it's wavelength will get shorter. And,
00:15:52 --> 00:15:55 and that's saying it's compressed is
00:15:55 --> 00:15:56 pretty well, you know, that's pretty
00:15:56 --> 00:15:59 well what happens. It's like uh um you
00:15:59 --> 00:16:02 know the the the good old uh ambulance
00:16:02 --> 00:16:04 siren or fire engine siren or whatever
00:16:04 --> 00:16:06 it is coming towards you uh which
00:16:06 --> 00:16:09 compresses the uh the sound waves and
00:16:09 --> 00:16:11 the result is an increase in pitch which
00:16:11 --> 00:16:12 corresponds to a shortening of
00:16:12 --> 00:16:15 wavelength. So that's standard physics
00:16:15 --> 00:16:18 we we can detect uh by the Doppler shift
00:16:18 --> 00:16:21 anything coming towards us uh by the
00:16:21 --> 00:16:22 fact that it light is shifted towards
00:16:22 --> 00:16:27 the blue end of the spectrum. Um but um
00:16:27 --> 00:16:30 the the first bit of the question about
00:16:30 --> 00:16:32 galaxies
00:16:32 --> 00:16:36 earlier galaxies traveling towards us um
00:16:36 --> 00:16:38 we
00:16:38 --> 00:16:41 we when we think about galaxies we have
00:16:41 --> 00:16:43 two
00:16:43 --> 00:16:45 two different velocities involved. One
00:16:45 --> 00:16:48 is the velocity of a galaxy as it's
00:16:48 --> 00:16:50 carried along by the expansion of the
00:16:50 --> 00:16:54 universe. uh and that is what we measure
00:16:54 --> 00:16:57 as a red shift. Uh the expansion of the
00:16:57 --> 00:16:59 universe is carrying galaxies away from
00:16:59 --> 00:17:01 us and so their light is being
00:17:01 --> 00:17:04 redshifted. Uh and by the time you get
00:17:04 --> 00:17:06 to these really early galaxies where
00:17:06 --> 00:17:09 you're looking back uh almost the whole
00:17:09 --> 00:17:11 edge of the universe, the red shift is
00:17:11 --> 00:17:13 very considerable. It's a factor of 13
00:17:13 --> 00:17:15 or 14 something like that. We're given
00:17:15 --> 00:17:18 the name zed. Uh the red shift is about
00:17:18 --> 00:17:21 14. So, um, a big part, no, that's not
00:17:21 --> 00:17:23 true. Uh, that's that's me confusing the
00:17:24 --> 00:17:27 age with the red shift. Forget that bit.
00:17:27 --> 00:17:29 But the the numbers quite high. The red
00:17:29 --> 00:17:30 shifts are probably five or six or
00:17:30 --> 00:17:32 something like that. Uh, but it's still
00:17:32 --> 00:17:35 it's still a a high level of the, you
00:17:35 --> 00:17:36 know, the light being stretched out by
00:17:36 --> 00:17:38 the expansion of the universe. So,
00:17:38 --> 00:17:41 that's one velocity, but galaxies can
00:17:41 --> 00:17:44 have a superimposed on that a velocity
00:17:44 --> 00:17:47 which we call a peculiar motion, its own
00:17:47 --> 00:17:50 velocity. uh caused by local, you know,
00:17:50 --> 00:17:53 local edies in space or whatever uh that
00:17:53 --> 00:17:56 that might um move a galaxy towards us.
00:17:56 --> 00:17:58 It's the gravitational field that it's
00:17:58 --> 00:18:02 exposed to. Very much like um the the
00:18:02 --> 00:18:04 analog is always a river carrying you
00:18:04 --> 00:18:06 along. Uh and if you're in a rowbo, you
00:18:06 --> 00:18:08 can move relative to the river, but the
00:18:08 --> 00:18:09 river is always carrying you along.
00:18:09 --> 00:18:11 That's exactly what's happening with the
00:18:11 --> 00:18:13 Hubble flow, the the expansion of the
00:18:13 --> 00:18:15 universe. And these peculiar motions are
00:18:15 --> 00:18:17 superimposed on that, but they're much
00:18:17 --> 00:18:18 much less
00:18:18 --> 00:18:22 >> than the motion uh at those distances or
00:18:22 --> 00:18:24 look back times. It's much much less
00:18:24 --> 00:18:27 than the expansion flow of the universe.
00:18:28 --> 00:18:29 So no, there won't be anything hidden
00:18:30 --> 00:18:31 from us that's coming towards us. I
00:18:31 --> 00:18:33 don't think it's a interesting
00:18:33 --> 00:18:35 suggestion, but uh everything's moving
00:18:35 --> 00:18:37 away from us at this very high velocity
00:18:37 --> 00:18:39 at those distances.
00:18:39 --> 00:18:41 >> Of course. Um, Nick, if you want to
00:18:41 --> 00:18:43 check with us in a million years or so,
00:18:43 --> 00:18:45 we might have an alternative answer.
00:18:45 --> 00:18:47 >> Well, that's true. Uh, put that in your
00:18:47 --> 00:18:49 diary and we'll we'll uh I'll I'll mark
00:18:49 --> 00:18:51 it with an asterisk knowing that it's
00:18:51 --> 00:18:54 homework for a million years time.
00:18:54 --> 00:18:58 >> Yes, it's good. Um, and I'm really
00:18:58 --> 00:18:59 disappointed that the people who make
00:18:59 --> 00:19:06 diaries haven't gone ahead that far yet.
00:19:06 --> 00:19:08 >> Thanks, Nick. Um, probably not, I think,
00:19:08 --> 00:19:11 is the the answer. Um, but thanks for
00:19:11 --> 00:19:13 the question. Thanks to everyone who
00:19:13 --> 00:19:14 sent in questions. Keep them coming. You
00:19:14 --> 00:19:15 can do that via our website,
00:19:15 --> 00:19:18 spacenutspodcast.com, spacenuts.io,
00:19:18 --> 00:19:22 which has two options. The AMA tab at
00:19:22 --> 00:19:23 the top where you can send us text and
00:19:23 --> 00:19:27 audio or the send us your questions uh
00:19:27 --> 00:19:28 button on the right hand side of our
00:19:28 --> 00:19:30 home screens. Don't forget to tell us
00:19:30 --> 00:19:32 who you are and where you're from. And
00:19:32 --> 00:19:34 you can probably upload your audio
00:19:34 --> 00:19:36 questions on any device as long as
00:19:36 --> 00:19:38 you've got a microphone and mobile
00:19:38 --> 00:19:40 phones are perfect for this. Uh but a
00:19:40 --> 00:19:42 lot of people have home computers with
00:19:42 --> 00:19:45 mics built in, etc., etc., etc. Always
00:19:45 --> 00:19:48 happy to hear from you. Uh Fred, thanks
00:19:48 --> 00:19:50 so much. We're done with another
00:19:50 --> 00:19:52 episode. Jeez, we're them up.
00:19:52 --> 00:19:53 >> We are wrapping them up. Good to talk to
00:19:53 --> 00:19:56 you, Andrew. And we'll speak again soon.
00:19:56 --> 00:19:58 >> Indeed, we will. Professor Fred Watson,
00:19:58 --> 00:20:00 astronomer at large. And thanks to Hugh
00:20:00 --> 00:20:04 in the studio for collecting
00:20:04 --> 00:20:05 not much, but uh we thank him anyway.
00:20:06 --> 00:20:07 And from me, Andrew Dunley, thanks for
00:20:07 --> 00:20:09 your company. See you on the very next
00:20:09 --> 00:20:11 episode of Space Nuts. Bye-bye.
00:20:12 --> 00:20:13 >> Space Nuts.
00:20:13 --> 00:20:15 >> You've been listening to the Space Nuts
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