Cosmic Queries: Understanding Black Holes, Galactic Centres, and Mars Days

WEBVTT

0
00:00:00.400 --> 00:00:02.160
Andrew Dunkley: Hello again and thank you for joining us on

1
00:00:02.160 --> 00:00:04.120
another episode of Space Nuts. This is a Q

2
00:00:04.120 --> 00:00:06.160
and A edition where we take audience

3
00:00:06.240 --> 00:00:09.000
questions. We put them on paper and then we

4
00:00:09.000 --> 00:00:11.680
put them on a roll that goes on a little

5
00:00:11.680 --> 00:00:14.520
thing in a bathroom. Or we could

6
00:00:14.520 --> 00:00:16.880
answer them. We can do that. Uh, coming up

7
00:00:16.880 --> 00:00:19.760
today we have questions, uh, uh,

8
00:00:19.760 --> 00:00:22.760
from John about Martian days. The length

9
00:00:22.760 --> 00:00:25.600
of a Martian day. It's close, but is it

10
00:00:25.600 --> 00:00:28.480
close enough to Earth standard? We'll discuss

11
00:00:28.480 --> 00:00:31.400
that. Uh, the growth of a black

12
00:00:31.400 --> 00:00:33.740
hole has been, uh, brought up again.

13
00:00:34.120 --> 00:00:36.660
Uh, we've got a, um, a question, uh,

14
00:00:36.900 --> 00:00:39.180
from an 11 year old named Thomas. Hi, Thomas.

15
00:00:39.420 --> 00:00:41.900
He wants to talk about the galactic centre.

16
00:00:42.060 --> 00:00:44.900
And Paul is asking our, uh, about

17
00:00:44.900 --> 00:00:47.899
our galactic location. So we'll deal with

18
00:00:47.899 --> 00:00:50.780
all of that today on this episode of Space

19
00:00:50.780 --> 00:00:51.340
Nuts.

20
00:00:51.500 --> 00:00:53.980
Professor Fred Watson: 15 seconds. Guidance is internal.

21
00:00:54.220 --> 00:00:56.940
10, 9. Ignition

22
00:00:56.940 --> 00:00:57.900
sequence start.

23
00:00:58.140 --> 00:00:59.100
Professor Fred Watson: Space Nuts.

24
00:00:59.100 --> 00:01:01.944
Professor Fred Watson: 5, 4, 3. 2. 1. 2, 3, 4,

25
00:01:02.016 --> 00:01:04.360
5, 5, 4, 3. Space

26
00:01:04.440 --> 00:01:07.000
Nuts astronauts report it feels good.

27
00:01:08.200 --> 00:01:11.160
Andrew Dunkley: Joining us again to sort all that out is

28
00:01:11.160 --> 00:01:13.120
Professor Fred Watson Watson, astronomer at

29
00:01:13.120 --> 00:01:14.120
large. Hello, Fred Watson.

30
00:01:14.200 --> 00:01:16.040
Professor Fred Watson: Hello, Andrew. Good to see you again.

31
00:01:16.540 --> 00:01:17.720
Andrew Dunkley: Uh, good to see you too.

32
00:01:18.200 --> 00:01:20.280
Professor Fred Watson: Yes. Despite the hole in my head.

33
00:01:20.520 --> 00:01:23.400
Andrew Dunkley: Yeah, yeah. It doesn't look any better than

34
00:01:23.400 --> 00:01:23.960
last time.

35
00:01:24.840 --> 00:01:25.960
Professor Fred Watson: It doesn't, does it?

36
00:01:26.040 --> 00:01:28.840
Andrew Dunkley: No, I mean, you know, it's only been

37
00:01:28.840 --> 00:01:30.640
minutes. You'd think it would have improved

38
00:01:30.640 --> 00:01:31.080
by now.

39
00:01:32.360 --> 00:01:34.280
Professor Fred Watson: That's what happens when you walk into a,

40
00:01:34.440 --> 00:01:36.820
when you walk into a closed screen door.

41
00:01:36.820 --> 00:01:37.380
Andrew Dunkley: Yeah.

42
00:01:37.620 --> 00:01:39.380
Professor Fred Watson: In the dark it hurts.

43
00:01:40.660 --> 00:01:43.420
Andrew Dunkley: Now that's why they have stuff, um, on,

44
00:01:43.420 --> 00:01:46.210
on glass sliding doors, you know,

45
00:01:46.210 --> 00:01:48.740
uh, that, that's a standard safety standard

46
00:01:48.740 --> 00:01:50.860
required these days so that, you know, the

47
00:01:50.860 --> 00:01:51.620
door is there.

48
00:01:51.700 --> 00:01:52.180
Professor Fred Watson: Yeah.

49
00:01:52.740 --> 00:01:54.780
Andrew Dunkley: But when it's nighttime and it's a screen

50
00:01:54.780 --> 00:01:56.900
door. Not, not many excuses left there,

51
00:01:56.900 --> 00:01:57.260
Fred Watson.

52
00:01:57.260 --> 00:02:00.060
Professor Fred Watson: Really only stupidity, I think is the,

53
00:02:00.060 --> 00:02:02.940
is the last one. But that's, that's

54
00:02:02.940 --> 00:02:04.580
my excuse many, many times.

55
00:02:05.620 --> 00:02:08.560
Andrew Dunkley: Yeah, well, we've all done it.

56
00:02:09.760 --> 00:02:11.600
Shall we try and answer these questions?

57
00:02:11.600 --> 00:02:12.160
Professor Fred Watson: We should.

58
00:02:12.320 --> 00:02:14.560
Andrew Dunkley: Okay, let's go to question one. This one

59
00:02:14.560 --> 00:02:16.000
comes from John.

60
00:02:16.830 --> 00:02:19.520
Uh, we know that the Martian Day is 39

61
00:02:19.520 --> 00:02:22.240
minutes longer than an Earth Day. That's

62
00:02:22.240 --> 00:02:25.200
about four and a half hours a week. Uh, when

63
00:02:25.280 --> 00:02:27.920
and if Mars is populated with humans,

64
00:02:28.320 --> 00:02:31.040
how would we work with the longer

65
00:02:31.040 --> 00:02:33.400
day, week? Would human

66
00:02:33.400 --> 00:02:36.160
biology tend to keep to the 24 hour

67
00:02:36.160 --> 00:02:38.960
day or would we adapt to a longer day,

68
00:02:38.960 --> 00:02:41.180
Night. Cycle. Cycle. Thanks. Love the show

69
00:02:41.180 --> 00:02:43.420
and have been a listener since you started.

70
00:02:43.740 --> 00:02:46.300
Wow, you've got a lot of spare time, John.

71
00:02:47.020 --> 00:02:49.580
Thank you so much, uh, for sending your

72
00:02:49.580 --> 00:02:52.240
question in and hope all is well. Uh,

73
00:02:52.380 --> 00:02:54.220
I love this question because

74
00:02:55.660 --> 00:02:58.340
you've got a planet that is close enough for

75
00:02:58.340 --> 00:03:00.380
us to get to in the not too distant future.

76
00:03:00.700 --> 00:03:03.180
Probably not a

77
00:03:03.180 --> 00:03:04.940
permanent settlement, but a rotating

78
00:03:04.940 --> 00:03:07.580
settlement of some kind will be the initial

79
00:03:07.580 --> 00:03:10.300
stages of humans being on Mars.

80
00:03:11.540 --> 00:03:14.500
And yet you've got an extra 39

81
00:03:14.500 --> 00:03:17.220
minutes a day to deal with what

82
00:03:17.700 --> 00:03:19.060
is going to be the impact.

83
00:03:20.690 --> 00:03:22.820
Professor Fred Watson: Um, I think we've already, we have

84
00:03:23.590 --> 00:03:25.980
um, a lot of data on this

85
00:03:25.980 --> 00:03:28.340
Andrew Dunkley: because the, we've already talked about this

86
00:03:28.340 --> 00:03:30.380
once before in the deep dark past. Quite a

87
00:03:30.380 --> 00:03:31.340
lot came up again.

88
00:03:31.340 --> 00:03:33.830
Professor Fred Watson: Yeah, yeah, because of the, the um,

89
00:03:34.260 --> 00:03:36.740
rover, um, drivers, they,

90
00:03:38.730 --> 00:03:41.610
the people who are uh, in command of,

91
00:03:41.610 --> 00:03:42.970
if I can put it that way, because they don't

92
00:03:42.970 --> 00:03:45.170
actually drive them directly but in command

93
00:03:45.170 --> 00:03:48.130
of the rovers on Mars and the two active

94
00:03:48.130 --> 00:03:50.150
NASA ones at the moment are Curiosity. Uh,

95
00:03:50.770 --> 00:03:53.529
and perseverance. Uh, they

96
00:03:53.930 --> 00:03:54.850
Adapt to uh,

97
00:03:56.890 --> 00:03:58.810
24 hours, 39 minutes day,

98
00:03:59.770 --> 00:04:02.610
and do it quite successfully

99
00:04:02.610 --> 00:04:05.530
as far as I've been able to work out.

100
00:04:06.890 --> 00:04:09.330
Andrew Dunkley: Well I hope so, yeah.

101
00:04:09.330 --> 00:04:11.450
Professor Fred Watson: Otherwise there might be a pile up on Mars.

102
00:04:11.750 --> 00:04:14.050
Um, and in fact the reason why I said they

103
00:04:14.050 --> 00:04:16.450
don't actually drive them is because the

104
00:04:16.450 --> 00:04:19.410
rovers themselves have got to be to some

105
00:04:19.410 --> 00:04:22.250
extent autonomous because of the delay

106
00:04:22.890 --> 00:04:25.850
in signal time to get between Mars and

107
00:04:26.090 --> 00:04:28.650
the Earth. You can't have video coming back

108
00:04:28.650 --> 00:04:30.690
from your rover and a steering wheel so that

109
00:04:30.690 --> 00:04:32.730
you respond to that because you'd have a sort

110
00:04:32.730 --> 00:04:35.050
of 20 or 30 minute delay probably before

111
00:04:36.030 --> 00:04:38.950
uh, before um, you turn, before

112
00:04:38.950 --> 00:04:41.430
the wheels turned on the rover.

113
00:04:41.910 --> 00:04:44.710
Andrew Dunkley: I would imagine that the manual

114
00:04:44.870 --> 00:04:47.350
driving of a rover from Earth

115
00:04:47.670 --> 00:04:50.630
on Mars would be damn near impossible because

116
00:04:51.030 --> 00:04:53.430
even your images would be out of sync with.

117
00:04:53.430 --> 00:04:54.670
Professor Fred Watson: Everything's out of sync. That's right.

118
00:04:54.670 --> 00:04:56.390
Andrew Dunkley: So you say, oh, there's a rock coming up.

119
00:04:56.630 --> 00:04:59.470
That was 40 minutes ago, I'll turn

120
00:04:59.470 --> 00:05:00.470
left now.

121
00:05:01.590 --> 00:05:02.150
Martin Berman Gorvine: Oops.

122
00:05:03.350 --> 00:05:03.470
Andrew Dunkley: Yeah.

123
00:05:03.470 --> 00:05:05.560
Professor Fred Watson: Ah, um,

124
00:05:06.400 --> 00:05:09.120
so the rovers drive themselves basically,

125
00:05:09.560 --> 00:05:12.300
uh, with a lot of assistance, um,

126
00:05:12.840 --> 00:05:15.760
and monitoring from Earth, uh, in order

127
00:05:15.840 --> 00:05:18.560
to see what's coming up and see what

128
00:05:19.040 --> 00:05:21.880
the onboard computers are doing in terms of

129
00:05:21.880 --> 00:05:23.840
what route they're taking through the rocks

130
00:05:23.840 --> 00:05:26.360
and debris on Mars. Ah, uh,

131
00:05:27.080 --> 00:05:29.920
um, but those people, as I understand

132
00:05:29.920 --> 00:05:32.800
it, do go on to uh, this 24

133
00:05:32.800 --> 00:05:35.440
hours and 39 minutes day length.

134
00:05:35.880 --> 00:05:37.980
Uh, I think it's nearing enough to our 24

135
00:05:37.980 --> 00:05:39.900
hours that I think they adapt quite quickly.

136
00:05:39.900 --> 00:05:41.860
From my recollection of our previous

137
00:05:41.860 --> 00:05:43.340
conversation about this Andrew.

138
00:05:44.380 --> 00:05:47.260
Andrew Dunkley: Yeah, if I remember rightly, we were talking

139
00:05:47.260 --> 00:05:49.180
about the fact that if you're going to stay

140
00:05:49.180 --> 00:05:51.860
on Mars long term you would

141
00:05:51.860 --> 00:05:53.980
have to adapt.

142
00:05:54.830 --> 00:05:57.340
Um, you wouldn't adapt naturally

143
00:05:58.940 --> 00:06:01.820
at all you'd have to take catnaps

144
00:06:01.820 --> 00:06:04.810
or something like that to catch up. Um,

145
00:06:05.100 --> 00:06:07.340
or something to that effect.

146
00:06:08.220 --> 00:06:11.040
Professor Fred Watson: Well, yes. So your circadian rhythms

147
00:06:11.040 --> 00:06:13.560
would, they'd be under stress, they'd change

148
00:06:15.880 --> 00:06:18.160
and I suppose you'd have a permanent feeling

149
00:06:18.160 --> 00:06:20.880
of jet lag. Probably what it feels like.

150
00:06:20.880 --> 00:06:23.510
Andrew Dunkley: It would be tough. I read an article, uh,

151
00:06:23.800 --> 00:06:26.440
last weekend which I found fascinating

152
00:06:26.440 --> 00:06:29.320
and it was, um, detailing how

153
00:06:29.320 --> 00:06:32.120
the eight hour night cycle

154
00:06:32.200 --> 00:06:34.600
that humans have, like going to bed for eight

155
00:06:34.600 --> 00:06:36.120
hours, is a myth.

156
00:06:36.880 --> 00:06:37.200
Professor Fred Watson: Yes.

157
00:06:37.520 --> 00:06:40.320
Andrew Dunkley: And that, um, it was actually

158
00:06:40.320 --> 00:06:42.800
something invented by a mattress company back

159
00:06:42.800 --> 00:06:45.280
in 1938. Have you heard this?

160
00:06:45.520 --> 00:06:48.080
Professor Fred Watson: No. Yes, I do know that

161
00:06:48.320 --> 00:06:50.080
we used to sleep twice in the night.

162
00:06:50.400 --> 00:06:53.240
Andrew Dunkley: That's right. So you go to bed at like 9 o'

163
00:06:53.240 --> 00:06:55.600
clock and you'd sleep for four hours

164
00:06:56.000 --> 00:06:58.200
and then you'd get up for two hours and you'd

165
00:06:58.200 --> 00:07:00.760
do stuff like, stuff we can't talk about on

166
00:07:00.760 --> 00:07:03.270
this podcast, but other stuff like,

167
00:07:03.270 --> 00:07:05.520
um, they cited a couple of,

168
00:07:07.150 --> 00:07:10.080
um, famous people, um, whose names have

169
00:07:10.080 --> 00:07:12.300
dropped straight out of my head. Um,

170
00:07:13.000 --> 00:07:15.960
William Shakespeare apparently wrote

171
00:07:16.040 --> 00:07:18.520
a lot of his famous works between

172
00:07:18.920 --> 00:07:21.640
1 and 3 in the morning when he got up and

173
00:07:21.640 --> 00:07:24.200
then he'd go back to bed for four hours. And,

174
00:07:24.380 --> 00:07:26.760
uh, Beethoven did the same thing with some of

175
00:07:26.760 --> 00:07:28.840
his symphonies. He wrote some of the

176
00:07:29.640 --> 00:07:31.880
best works that he ever created

177
00:07:32.280 --> 00:07:35.110
at 3 o' clock in the morning, um,

178
00:07:35.110 --> 00:07:37.730
during his wake time between his two sleeps.

179
00:07:38.290 --> 00:07:40.690
So the eight hour sleep

180
00:07:41.730 --> 00:07:44.330
that we have at night was an invention

181
00:07:44.330 --> 00:07:47.210
apparently, to sell mattresses. That's

182
00:07:47.210 --> 00:07:49.570
what I'm told. Look, I haven't confirmed or

183
00:07:49.570 --> 00:07:52.530
denied that, but it seems

184
00:07:52.530 --> 00:07:53.570
possible, I suppose.

185
00:07:54.210 --> 00:07:56.770
Professor Fred Watson: Well, yes, I think we have,

186
00:07:58.080 --> 00:08:00.970
uh, I think, um, there's been evidence

187
00:08:00.970 --> 00:08:02.970
from the earliest times,

188
00:08:04.070 --> 00:08:06.570
uh, the times when people truly were ancient

189
00:08:06.570 --> 00:08:08.970
peoples back thousands of years ago,

190
00:08:09.530 --> 00:08:10.930
uh, that that's how they lived their lives.

191
00:08:10.930 --> 00:08:13.170
Exactly as you've said. And maybe the last

192
00:08:13.170 --> 00:08:16.010
vestiges of that were keeping

193
00:08:16.010 --> 00:08:17.650
going in Shakespeare's time and then in

194
00:08:17.650 --> 00:08:20.570
Beethoven's time. Um, there

195
00:08:20.570 --> 00:08:22.530
weren't that many clocks around then. There

196
00:08:22.530 --> 00:08:24.810
were some, but not that many. It wasn't like

197
00:08:24.810 --> 00:08:27.650
you had a smart watch by your bedside or

198
00:08:27.650 --> 00:08:30.450
anything like that. So, uh, it would be a

199
00:08:30.450 --> 00:08:33.060
natural rhythm that they would use, uh,

200
00:08:34.710 --> 00:08:35.990
to sleep and wake up.

201
00:08:36.150 --> 00:08:38.990
Andrew Dunkley: Yes. Modernization certainly

202
00:08:38.990 --> 00:08:40.030
messed us up, hasn't it?

203
00:08:40.030 --> 00:08:41.590
Professor Fred Watson: Yeah, yeah, that's right. I think in that

204
00:08:41.590 --> 00:08:42.230
case it has.

205
00:08:42.550 --> 00:08:44.970
Andrew Dunkley: And I think, uh, on Mars, um,

206
00:08:45.430 --> 00:08:47.190
it will be a pretty difficult thing,

207
00:08:47.750 --> 00:08:49.590
Professor Fred Watson: I imagine it may be.

208
00:08:50.230 --> 00:08:53.190
So maybe I can just sidestep here slightly,

209
00:08:53.190 --> 00:08:56.190
Andrew, um, because I would very much like to

210
00:08:56.190 --> 00:08:58.750
know uh, what

211
00:08:58.750 --> 00:09:01.030
answer one of our listeners would give to

212
00:09:01.030 --> 00:09:03.950
that, and that's Dr. Heidi DeBlock who's

213
00:09:03.950 --> 00:09:06.110
I think based in Houston, if I remember

214
00:09:06.350 --> 00:09:09.070
rightly, who is basically a space medic.

215
00:09:09.610 --> 00:09:12.350
Uh, and um, uh, it will be very interesting

216
00:09:12.350 --> 00:09:15.350
to hear her take on how humans will adapt

217
00:09:15.350 --> 00:09:18.270
to that. And if I may, she was in touch with

218
00:09:18.270 --> 00:09:20.790
us recently to comment on one of our earlier

219
00:09:20.790 --> 00:09:23.070
questions. Would it be all right if I. Yeah.

220
00:09:23.470 --> 00:09:26.030
Andrew Dunkley: And that was when we were talking about how

221
00:09:26.030 --> 00:09:28.880
people deal with um, gravity when they

222
00:09:28.880 --> 00:09:30.720
get back on Earth after being out in space

223
00:09:30.720 --> 00:09:32.080
for a while, correct?

224
00:09:32.080 --> 00:09:35.040
Professor Fred Watson: Yes, that's right. Uh, she

225
00:09:35.040 --> 00:09:38.040
says, um, I just finished the July

226
00:09:38.040 --> 00:09:40.520
5th space nuts and wanted to help answer the

227
00:09:40.520 --> 00:09:42.240
question about how the astronauts feel when

228
00:09:42.240 --> 00:09:44.520
they land back on Earth. Of course I haven't

229
00:09:44.520 --> 00:09:47.080
experienced it in person, but have worked

230
00:09:47.080 --> 00:09:49.280
with plenty of astronauts at landing. In

231
00:09:49.280 --> 00:09:51.840
particular, all of our, uh, physiology

232
00:09:51.840 --> 00:09:54.280
changes in space as we are designed for

233
00:09:54.280 --> 00:09:57.160
1G. Some astronauts are pretty good when

234
00:09:57.160 --> 00:09:58.720
they land, especially those who are on the

235
00:09:58.720 --> 00:10:00.740
shuttle and in space. For short time.

236
00:10:01.860 --> 00:10:04.820
Sorry, for a short time. Some had significant

237
00:10:04.980 --> 00:10:07.860
problems. They stemmed from the orthostatic

238
00:10:07.940 --> 00:10:10.380
hypotension as a result from the

239
00:10:10.380 --> 00:10:13.260
cardiovascular changes, some of the changes

240
00:10:13.260 --> 00:10:15.420
in the inner ear with balance and knowing

241
00:10:15.420 --> 00:10:17.460
where you physically are, some mild

242
00:10:17.460 --> 00:10:20.340
weaknesses, et cetera. These changes are more

243
00:10:20.340 --> 00:10:23.020
exaggerated with long duration flight in the

244
00:10:23.020 --> 00:10:25.500
International Space Station. The vision

245
00:10:25.500 --> 00:10:28.260
problems are called SANS S A N S

246
00:10:28.500 --> 00:10:30.740
which is an acronym for Spaceflight

247
00:10:30.740 --> 00:10:32.960
Associated Neuro Ocular

248
00:10:33.040 --> 00:10:36.000
Syndrome. Our lab is studying that

249
00:10:36.000 --> 00:10:38.480
as well. That's a whole other fascinating

250
00:10:38.480 --> 00:10:41.480
issue. I could tell you some

251
00:10:41.480 --> 00:10:43.760
fun storeys about astronauts and how weird

252
00:10:43.760 --> 00:10:46.360
some of them feel when they get back. Maybe

253
00:10:46.360 --> 00:10:48.280
we need to get Heidi on the show. Maybe we

254
00:10:48.280 --> 00:10:50.710
do. Yeah, no, that's um,

255
00:10:51.530 --> 00:10:53.920
uh, she has another interesting comment

256
00:10:53.920 --> 00:10:56.520
actually about the, about the uh,

257
00:10:56.520 --> 00:10:58.680
Voyager Golden Record. But we might talk

258
00:10:58.680 --> 00:11:00.650
about that another time. Fair enough.

259
00:11:00.650 --> 00:11:02.330
Andrew Dunkley: Yeah. All right. Thank you, Heidi. That was

260
00:11:02.330 --> 00:11:02.970
fascinating.

261
00:11:02.970 --> 00:11:03.450
Professor Fred Watson: Yeah.

262
00:11:03.500 --> 00:11:06.130
Andrew Dunkley: Um, what an amazing job working with all

263
00:11:06.130 --> 00:11:09.090
those incredible people trying to

264
00:11:09.090 --> 00:11:11.130
figure out how to deal with the zero G

265
00:11:11.290 --> 00:11:13.810
problem. But uh, on Mars the gravity will

266
00:11:13.810 --> 00:11:16.770
also be an issue. So, um, there's

267
00:11:16.770 --> 00:11:19.330
a heck of a lot that needs to be sorted out

268
00:11:19.330 --> 00:11:22.330
before we um, put people down

269
00:11:22.330 --> 00:11:25.290
there. Because it's such a long trip to

270
00:11:25.290 --> 00:11:26.690
get there. It's not like you can go, uh, ah,

271
00:11:26.690 --> 00:11:28.330
no, this is no good and come straight back.

272
00:11:28.330 --> 00:11:30.610
Professor Fred Watson: It's not going to be that simple. That's

273
00:11:30.610 --> 00:11:32.230
right. Once you're on your way. On your way.

274
00:11:32.230 --> 00:11:34.550
And the only way back is to keep going.

275
00:11:34.950 --> 00:11:37.670
Andrew Dunkley: Yeah, exactly. Thanks for the question, John.

276
00:11:37.880 --> 00:11:40.750
Uh, well asked. And yeah, it's not

277
00:11:40.750 --> 00:11:43.610
going to be a snack, that's for sure. Let's,

278
00:11:43.610 --> 00:11:45.670
uh, move on to our, uh, next question from

279
00:11:45.750 --> 00:11:46.310
Dan.

280
00:11:47.030 --> 00:11:49.270
Martin Berman Gorvine: Hello gentlemen. Dan from the Gold coast

281
00:11:49.270 --> 00:11:51.510
here. Uh, now I know you've been

282
00:11:52.710 --> 00:11:55.190
asked a million questions about black holes,

283
00:11:55.690 --> 00:11:57.990
uh, but I do have a quick two parter and I'm

284
00:11:57.990 --> 00:11:59.310
hoping that's something you've never had to

285
00:11:59.310 --> 00:12:02.270
answer before. Really quickly, from the

286
00:12:02.270 --> 00:12:05.030
point when a black hole is born,

287
00:12:05.030 --> 00:12:07.030
birth, created, whatever you want to call it,

288
00:12:07.410 --> 00:12:10.150
uh, how quickly is that growing to become a,

289
00:12:10.390 --> 00:12:12.190
let's say, supermassive black hole or just

290
00:12:12.190 --> 00:12:13.760
something a lot bigger? Um,

291
00:12:14.950 --> 00:12:17.830
or is that not how black holes work and I'm

292
00:12:17.830 --> 00:12:19.670
not understanding it properly? Two,

293
00:12:21.190 --> 00:12:23.430
Hypothetically, uh, if there's no matter or

294
00:12:23.430 --> 00:12:25.510
energy or anything surrounding

295
00:12:26.370 --> 00:12:29.090
the black hole to take in and let's say

296
00:12:29.090 --> 00:12:32.010
eat, uh, is the black hole still going to

297
00:12:32.010 --> 00:12:34.850
grow? Is there more to the black hole growing

298
00:12:34.850 --> 00:12:36.690
than I understand?

299
00:12:37.640 --> 00:12:39.770
Um, yeah. Hopefully that made sense and

300
00:12:39.770 --> 00:12:41.809
hopefully it's worth answering. Love the

301
00:12:41.809 --> 00:12:44.570
show. Love you guys. Work. Cheers,

302
00:12:44.570 --> 00:12:45.010
bye.

303
00:12:45.330 --> 00:12:47.810
Andrew Dunkley: Thank you, Dan. Uh, nice to hear from you.

304
00:12:48.060 --> 00:12:50.930
Uh, yeah, a couple of questions in that one.

305
00:12:51.000 --> 00:12:53.290
Um, we never talk about black holes, but we

306
00:12:53.290 --> 00:12:56.050
will today. Ah, speed of growth.

307
00:12:56.320 --> 00:12:58.730
Um, that's an interesting one. Um,

308
00:12:59.480 --> 00:13:02.160
given that we're starting to think that there

309
00:13:02.160 --> 00:13:04.600
were some absolutely

310
00:13:04.600 --> 00:13:07.440
enormous, um, black holes in the

311
00:13:07.440 --> 00:13:09.360
early universe. Um,

312
00:13:10.120 --> 00:13:13.000
and, and they're looking

313
00:13:13.000 --> 00:13:14.640
for more and more evidence to see what was

314
00:13:14.640 --> 00:13:17.160
going on early on. Um, but we've got some

315
00:13:17.400 --> 00:13:19.740
gargantuan ones still around. Uh,

316
00:13:20.040 --> 00:13:22.880
so how fast did they get that big? And

317
00:13:22.880 --> 00:13:25.750
I, um, I'm starting to think, Fred Watson,

318
00:13:25.750 --> 00:13:27.590
it wouldn't be a stock standard approach.

319
00:13:28.790 --> 00:13:31.430
Professor Fred Watson: Maybe not, maybe not. Uh, but I mean,

320
00:13:31.430 --> 00:13:33.830
Dan's asking, uh, one of the

321
00:13:33.990 --> 00:13:35.990
fundamental questions of astrophysics at the

322
00:13:35.990 --> 00:13:38.510
moment. This is a very hot topic. Uh, and

323
00:13:38.510 --> 00:13:40.510
what set the cat among the pigeons and made

324
00:13:40.510 --> 00:13:42.350
it a hot topic is the James Webb Space

325
00:13:42.350 --> 00:13:45.110
Telescope. Because, um, until

326
00:13:45.270 --> 00:13:48.150
that came along, the idea was

327
00:13:48.150 --> 00:13:51.080
that as basically as Daniel suggests,

328
00:13:51.080 --> 00:13:54.080
black holes were formed in

329
00:13:54.080 --> 00:13:56.760
the early universe by exploding stars that,

330
00:13:56.990 --> 00:13:59.320
um, collapsed at the end of their lives

331
00:13:59.800 --> 00:14:02.200
to form a black hole. The core would collapse

332
00:14:02.200 --> 00:14:04.440
to a black hole and that then

333
00:14:05.160 --> 00:14:07.960
over billions of years that black hole would

334
00:14:07.960 --> 00:14:10.800
grow. And eventually in our own epoch

335
00:14:10.800 --> 00:14:13.800
today, 13.8 billion years after the

336
00:14:13.800 --> 00:14:16.640
Big Bang, uh, you have supermassive black

337
00:14:16.640 --> 00:14:19.480
holes at the centre of every galaxy. That

338
00:14:19.480 --> 00:14:21.710
was the old wisdom. But the James Webb

339
00:14:21.710 --> 00:14:23.430
telescope has turned that completely on its

340
00:14:23.430 --> 00:14:25.990
head because we have serious

341
00:14:25.990 --> 00:14:28.630
evidence of supermassive black holes

342
00:14:29.030 --> 00:14:31.430
within the first 500 million years

343
00:14:32.150 --> 00:14:34.950
of the universe's existence. And that's

344
00:14:34.950 --> 00:14:37.750
too quick for, or too

345
00:14:37.750 --> 00:14:40.670
short a time for this, um, you

346
00:14:40.670 --> 00:14:42.630
know, this slow accretion of

347
00:14:43.190 --> 00:14:46.130
stuff, uh, as being the, um,

348
00:14:46.950 --> 00:14:49.130
the growth mechanism for black holes. Uh,

349
00:14:49.130 --> 00:14:51.110
it's too short a time for that to be the

350
00:14:51.110 --> 00:14:53.350
case. Uh, so

351
00:14:53.670 --> 00:14:56.670
either our ideas of how fast they gobble

352
00:14:56.670 --> 00:14:59.510
up matter is wrong. And they

353
00:14:59.510 --> 00:15:01.870
gobble up matter a lot faster than we

354
00:15:01.870 --> 00:15:03.830
thought. And we actually covered a storey on

355
00:15:03.830 --> 00:15:06.150
this, I think, about four or five episodes

356
00:15:06.150 --> 00:15:08.870
ago, because there are some scientists who

357
00:15:09.430 --> 00:15:11.750
came to conclusion that one of the things

358
00:15:11.750 --> 00:15:14.590
that we thought limited how fast a

359
00:15:14.590 --> 00:15:17.140
black hole can gobble stuff up, uh, was

360
00:15:17.140 --> 00:15:19.460
actually invalid under certain circumstances.

361
00:15:20.420 --> 00:15:23.420
So that's that one avenue of

362
00:15:23.420 --> 00:15:25.580
research that's come from the James Webb

363
00:15:25.580 --> 00:15:27.340
Telescope showing us that, ah, we've got

364
00:15:27.340 --> 00:15:29.340
these supermassive black holes in the early

365
00:15:29.340 --> 00:15:31.980
universe. But the other one is the idea of

366
00:15:31.980 --> 00:15:34.660
the little pink dots or the little red dots

367
00:15:34.660 --> 00:15:37.020
as they're called. And these are thought to

368
00:15:37.020 --> 00:15:39.700
be, uh, basically just

369
00:15:39.700 --> 00:15:42.260
clouds of gas, hydrogen gas,

370
00:15:42.420 --> 00:15:45.220
which are directly feeding a black hole

371
00:15:45.540 --> 00:15:48.320
that may have been formed in the Big Bang. In

372
00:15:48.320 --> 00:15:50.160
other words, you didn't have to have star

373
00:15:50.160 --> 00:15:53.080
formation and then stars blowing up to

374
00:15:53.080 --> 00:15:55.440
create black holes in order to kick this

375
00:15:55.440 --> 00:15:58.200
process off. The Big Bang itself might have

376
00:15:58.200 --> 00:15:59.800
kicked off the process of black hole

377
00:15:59.800 --> 00:16:02.280
formation by producing these things that we

378
00:16:02.280 --> 00:16:05.280
call primordial black holes. Um, and

379
00:16:05.440 --> 00:16:08.360
they may have turned out to be able

380
00:16:08.360 --> 00:16:10.880
to grow very quickly, um, by

381
00:16:10.960 --> 00:16:13.720
immersing themselves simply in big

382
00:16:13.720 --> 00:16:16.210
clouds of hydrogen and gobbling it all up.

383
00:16:16.370 --> 00:16:19.180
Andrew Dunkley: Yeah, of course, um,

384
00:16:19.330 --> 00:16:22.130
when they run out of stuff, they can't grow.

385
00:16:22.130 --> 00:16:22.770
Is that right?

386
00:16:23.170 --> 00:16:25.240
Professor Fred Watson: That's right. So that's part two of, uh,

387
00:16:25.240 --> 00:16:28.050
Dan's question. Uh, what happens when

388
00:16:28.050 --> 00:16:29.690
there's nothing there for them to eat and

389
00:16:29.690 --> 00:16:31.650
they become what we call quiescent black

390
00:16:31.650 --> 00:16:34.410
holes? They don't do anything. They're

391
00:16:34.410 --> 00:16:36.360
there, uh, and they're still, uh,

392
00:16:37.250 --> 00:16:39.930
things that, um, if a cloud of hydrogen

393
00:16:39.930 --> 00:16:42.910
strayed by, they might seize it

394
00:16:42.910 --> 00:16:45.350
by their own gravity and pull it in. But,

395
00:16:45.520 --> 00:16:47.430
um, they're not going to go out,

396
00:16:49.160 --> 00:16:51.110
um, roaming through the universe looking for

397
00:16:51.430 --> 00:16:53.390
stuff to accrete. In other words, looking for

398
00:16:53.390 --> 00:16:53.910
a snack.

399
00:16:54.150 --> 00:16:54.300
Professor Fred Watson: Yeah.

400
00:16:54.300 --> 00:16:57.150
Andrew Dunkley: Ah, I used to work with a guy whose nickname

401
00:16:57.150 --> 00:16:58.990
was quiescent black hole. He was there, but

402
00:16:58.990 --> 00:16:59.910
he didn't do anything.

403
00:17:03.030 --> 00:17:04.630
Professor Fred Watson: Yes, I think I know who you mean.

404
00:17:08.370 --> 00:17:10.760
Yeah. Anyway, quiescent black holes, uh, are,

405
00:17:10.760 --> 00:17:13.370
uh, basically what, uh, Dan has

406
00:17:13.370 --> 00:17:14.930
described. But the first part of his question

407
00:17:14.930 --> 00:17:17.850
is absolutely asking the same questions

408
00:17:17.850 --> 00:17:20.010
that today's astrophysicists are. Uh, it's

409
00:17:20.010 --> 00:17:22.450
one whose answer we don't know. But the

410
00:17:22.450 --> 00:17:24.890
consensus will emerge over the next. Probably

411
00:17:24.890 --> 00:17:26.890
not very long because we're getting so much

412
00:17:26.890 --> 00:17:29.890
data from the James Webb telescope that I

413
00:17:29.890 --> 00:17:31.530
think it'll be quite soon before this whole

414
00:17:31.530 --> 00:17:34.380
issue is resolved, I would think. Sorry,

415
00:17:34.460 --> 00:17:36.620
I was just going to say when, when there is

416
00:17:36.620 --> 00:17:38.900
hard evidence of a primordial black hole

417
00:17:38.900 --> 00:17:41.100
being discovered, one that was created in the

418
00:17:41.100 --> 00:17:43.900
Big Bang, then that'll be Nobel

419
00:17:43.900 --> 00:17:45.980
Prize winning science when we get to that

420
00:17:45.980 --> 00:17:48.140
stage. But it won't be us.

421
00:17:48.140 --> 00:17:50.670
Andrew Dunkley: Indeed, I was going to suggest that black um,

422
00:17:50.860 --> 00:17:53.540
holes are probably like humans. Consumption

423
00:17:53.540 --> 00:17:54.860
will decide how big they get.

424
00:17:55.980 --> 00:17:58.900
Professor Fred Watson: Maybe that's right, yeah, yeah, we'll have

425
00:17:58.900 --> 00:18:01.750
Andrew Dunkley: to wait and see. All right Dan. Hopefully uh,

426
00:18:02.160 --> 00:18:04.600
we covered that for you adequately. Thanks

427
00:18:04.600 --> 00:18:06.960
for sending in the question. This is Space

428
00:18:06.960 --> 00:18:08.880
Nuts with Andrew Dunkley and Professor

429
00:18:08.880 --> 00:18:09.720
Fred Watson Watson.

430
00:18:12.520 --> 00:18:14.760
Professor Fred Watson: Three, two, one.

431
00:18:15.400 --> 00:18:16.600
Andrew Dunkley: Space Nuts.

432
00:18:17.160 --> 00:18:19.520
Our next question, Fred Watson, comes from

433
00:18:19.520 --> 00:18:22.360
Thomas Reid. Thomas is 11 years old.

434
00:18:22.520 --> 00:18:24.560
He says something has been troubling me. In

435
00:18:24.560 --> 00:18:27.360
books I've read they say that the centres of

436
00:18:27.360 --> 00:18:30.320
galaxies are very big black holes and I

437
00:18:30.320 --> 00:18:32.460
have a few questions about them but uh, I'm

438
00:18:32.460 --> 00:18:34.820
only an 11 year old kid so the questions

439
00:18:34.820 --> 00:18:36.620
might sound silly but here they are. Now

440
00:18:36.620 --> 00:18:38.220
we've got five questions Fred Watson, so we

441
00:18:38.220 --> 00:18:41.220
can be brief on on them. Unless you wanted to

442
00:18:41.220 --> 00:18:43.940
sit here for another couple of hours. Um, if

443
00:18:43.940 --> 00:18:45.780
Jonty was here we would be a couple of hours.

444
00:18:46.700 --> 00:18:49.660
Um, can the galactic centre swallow all the

445
00:18:49.660 --> 00:18:52.380
stars and planets in the galaxy? How big are

446
00:18:52.380 --> 00:18:54.740
the galactic centres or do we not know,

447
00:18:55.260 --> 00:18:57.300
uh, if they can swallow up all the stars and

448
00:18:57.300 --> 00:19:00.020
planets. Is there a limit? If there is a

449
00:19:00.020 --> 00:19:02.620
limit, what is it? And if there is a

450
00:19:02.620 --> 00:19:05.440
limit happens when the limit is reached.

451
00:19:05.440 --> 00:19:07.440
Thank you for taking the time to read this

452
00:19:07.440 --> 00:19:09.560
and I would love it if you could reply. Well

453
00:19:09.560 --> 00:19:12.450
we are going to reply right now Thomas. Um,

454
00:19:13.680 --> 00:19:16.560
yeah, it's great that somebody, uh, so

455
00:19:16.560 --> 00:19:19.120
young is taking a keen interest in something

456
00:19:19.279 --> 00:19:22.180
so mysterious as a black hole. Uh,

457
00:19:22.240 --> 00:19:24.360
we want to start at the top. Can the galactic

458
00:19:24.360 --> 00:19:26.080
centre swallow all the stars and planets in

459
00:19:26.080 --> 00:19:26.720
the galaxy?

460
00:19:27.360 --> 00:19:30.240
Professor Fred Watson: Well so the answer is no. Um, so the

461
00:19:30.240 --> 00:19:33.040
galaxies are very big. Ours is about 100,000

462
00:19:33.040 --> 00:19:35.900
light years across. Uh, black holes

463
00:19:35.980 --> 00:19:38.500
have ah, a kind of sphere of

464
00:19:38.500 --> 00:19:41.380
influence um, which gravitationally

465
00:19:41.380 --> 00:19:43.620
stretches to the edge of the galaxy. But by

466
00:19:43.620 --> 00:19:45.740
the time you get there the gravity of the

467
00:19:45.740 --> 00:19:48.700
black hole is very, very weak indeed. And

468
00:19:48.700 --> 00:19:51.660
so it's only in the central region of a

469
00:19:51.660 --> 00:19:54.420
galaxy where you could get material

470
00:19:54.420 --> 00:19:57.100
being swallowed up uh, to create this

471
00:19:57.260 --> 00:19:58.980
activity that we talk about when we Talk

472
00:19:58.980 --> 00:20:01.500
about active black holes, uh, where

473
00:20:01.500 --> 00:20:03.780
there's, uh, an accretion disc, a disc of

474
00:20:03.780 --> 00:20:06.700
material swirling around it. And these jets,

475
00:20:07.240 --> 00:20:09.040
uh, point basically at right angles to the

476
00:20:09.040 --> 00:20:10.960
accretion disc, jets of material travelling

477
00:20:10.960 --> 00:20:12.520
at nearly the speed of light. Quite

478
00:20:12.520 --> 00:20:15.240
extraordinary. So, um, that's all

479
00:20:15.240 --> 00:20:17.760
great and black holes, like a factory or a

480
00:20:17.760 --> 00:20:20.520
furnace doing that, but its stretch is not

481
00:20:20.520 --> 00:20:23.439
very far. Uh, it's measured

482
00:20:23.439 --> 00:20:25.040
in light years, but not in hundreds of

483
00:20:25.040 --> 00:20:27.320
thousands of light years, which would have to

484
00:20:27.320 --> 00:20:29.640
be to grab everything in the galaxy. So the

485
00:20:29.640 --> 00:20:32.310
answer is no. The, uh, galactic centre, uh,

486
00:20:32.310 --> 00:20:34.800
black hole cannot swallow all the stars and

487
00:20:34.800 --> 00:20:35.960
planets in the galaxy.

488
00:20:36.630 --> 00:20:39.420
Andrew Dunkley: Uh, so Thomas can sleep well tonight. Um, how

489
00:20:39.420 --> 00:20:42.420
big are the galactic centres? Do we know how

490
00:20:42.420 --> 00:20:42.730
big?

491
00:20:42.730 --> 00:20:45.460
Professor Fred Watson: M. We do. Yes, we do, because

492
00:20:47.220 --> 00:20:50.180
we can measure the speed

493
00:20:50.180 --> 00:20:52.900
of rotation of stuff

494
00:20:52.900 --> 00:20:55.339
swirling around a black hole, if it's an

495
00:20:55.339 --> 00:20:58.220
active one. And that directly tells you

496
00:20:58.220 --> 00:21:01.140
the mass of the black hole. Um, because

497
00:21:01.140 --> 00:21:03.420
the bigger the black hole, the faster the

498
00:21:03.420 --> 00:21:06.420
stuff is going. And so, um, in terms

499
00:21:06.420 --> 00:21:09.360
of if, the if by

500
00:21:09.360 --> 00:21:12.040
big, Thomas means what's their mass?

501
00:21:12.590 --> 00:21:15.000
Uh, we can measure them quite accurately

502
00:21:15.240 --> 00:21:18.240
now because we can measure their mass. We can

503
00:21:18.240 --> 00:21:20.680
also work out their event horizon

504
00:21:20.760 --> 00:21:23.560
diameter or radius. The event horizon

505
00:21:23.880 --> 00:21:26.880
is that sort of imaginary sphere around a

506
00:21:26.880 --> 00:21:29.480
black hole beyond which light cannot

507
00:21:29.480 --> 00:21:32.160
escape. And so it would appear as a dark

508
00:21:32.160 --> 00:21:34.680
sphere. So the event horizon is the

509
00:21:34.920 --> 00:21:37.460
point of no return for anything going into a

510
00:21:37.460 --> 00:21:40.180
black hole. And it's also the point of no

511
00:21:40.180 --> 00:21:42.990
escape for light waves. Uh,

512
00:21:42.990 --> 00:21:45.540
so we can, knowing the mass of a black hole,

513
00:21:45.540 --> 00:21:48.180
we can calculate how big that event

514
00:21:48.180 --> 00:21:50.100
horizon would be. And some of the

515
00:21:50.100 --> 00:21:52.900
supermassive ones, ah, are really very big.

516
00:21:52.900 --> 00:21:55.020
They're measured in light years, tens of

517
00:21:55.020 --> 00:21:56.620
light years, perhaps for the supermassive

518
00:21:56.620 --> 00:21:57.220
black holes.

519
00:21:57.380 --> 00:22:00.180
Andrew Dunkley: Yeah. It's a level of enormity

520
00:22:00.180 --> 00:22:01.900
that you just struggle to get your head

521
00:22:01.900 --> 00:22:02.180
around.

522
00:22:02.180 --> 00:22:03.300
Professor Fred Watson: Yeah, yeah, I suppose.

523
00:22:03.300 --> 00:22:05.540
Andrew Dunkley: In terms of the rest of Thomas's questions,

524
00:22:05.620 --> 00:22:07.900
you've basically answered it with the answer

525
00:22:07.900 --> 00:22:10.040
to first question, because he's asking if

526
00:22:10.040 --> 00:22:11.680
they can swallow up all the stars and

527
00:22:11.680 --> 00:22:13.920
planets. Is there a limit? If there is a

528
00:22:13.920 --> 00:22:16.560
limit, what is it? Uh, and if there is a

529
00:22:16.560 --> 00:22:18.200
limit, what happens when the limit is

530
00:22:18.200 --> 00:22:20.960
reached? Well, the limit is probably

531
00:22:21.920 --> 00:22:24.719
the local area of the centre of the galaxy

532
00:22:24.800 --> 00:22:26.640
and what's available to eat.

533
00:22:26.880 --> 00:22:29.680
Professor Fred Watson: Yes, that's right. So the limiting factor,

534
00:22:29.680 --> 00:22:31.590
uh, is, um,

535
00:22:32.320 --> 00:22:34.920
basically what you might call the grasp of

536
00:22:34.920 --> 00:22:37.800
the black hole, how far it can reach to

537
00:22:37.800 --> 00:22:40.160
pull something in. And that is

538
00:22:40.380 --> 00:22:43.340
dependent on how fast the objects are moving.

539
00:22:43.340 --> 00:22:45.220
So you can have some stars and there are

540
00:22:45.220 --> 00:22:47.700
some. We've observed them, uh, with infrared

541
00:22:47.700 --> 00:22:50.540
radiation that are comfortably in

542
00:22:50.540 --> 00:22:52.300
orbit, uh, around

543
00:22:53.580 --> 00:22:55.580
the black hole at the centre of our own

544
00:22:55.580 --> 00:22:57.660
galaxy, which are not being pulled in,

545
00:22:57.660 --> 00:22:59.660
they're orbiting. And that's because their

546
00:22:59.660 --> 00:23:02.500
speed is enough to keep them out of the grasp

547
00:23:02.500 --> 00:23:05.460
of the black hole. Um, their distances from

548
00:23:05.460 --> 00:23:08.430
the black hole are measured in not two

549
00:23:08.430 --> 00:23:11.230
dissimilar units from the solar system. Sort

550
00:23:11.230 --> 00:23:13.390
of half a light day or something like that,

551
00:23:13.870 --> 00:23:16.870
you know, light day, that's

552
00:23:16.870 --> 00:23:18.710
the sort of measures that we're talking

553
00:23:18.710 --> 00:23:21.390
about. Um, which probably

554
00:23:21.710 --> 00:23:23.749
denies what I just said a few minutes ago

555
00:23:23.749 --> 00:23:26.590
about, um, some black hole event horizons

556
00:23:26.590 --> 00:23:28.790
being tens of light years. I don't think they

557
00:23:28.790 --> 00:23:30.110
are. I think they're smaller than that.

558
00:23:30.190 --> 00:23:30.750
Joe: Okay.

559
00:23:30.910 --> 00:23:33.110
Andrew Dunkley: I thought of a way to explain it to Thomas.

560
00:23:33.110 --> 00:23:35.040
So, uh, Thomas, you've won a competition

561
00:23:35.110 --> 00:23:37.270
kitchen and you can go to

562
00:23:37.430 --> 00:23:39.910
McDonald's and eat everything you want.

563
00:23:40.470 --> 00:23:43.230
Absolutely. Just keep eating until, you know,

564
00:23:43.230 --> 00:23:46.110
the cows come home. However, you aren't

565
00:23:46.110 --> 00:23:48.390
allowed to move from wherever you're standing

566
00:23:48.390 --> 00:23:50.710
and you can only eat what's within reach.

567
00:23:52.150 --> 00:23:54.830
Once you run out of food, you stop

568
00:23:54.830 --> 00:23:57.310
growing. And you're the black hole, by the

569
00:23:57.310 --> 00:23:59.230
way. How's that for an analogy?

570
00:23:59.230 --> 00:24:01.390
Professor Fred Watson: It's a nice one. I like it. Yes. Yeah,

571
00:24:01.390 --> 00:24:03.550
because your reach is the sort of

572
00:24:03.550 --> 00:24:06.390
gravitational force that you can exert. It's

573
00:24:06.390 --> 00:24:06.940
a good way of putting it.

574
00:24:07.090 --> 00:24:07.210
Professor Fred Watson: It.

575
00:24:07.210 --> 00:24:08.050
Andrew Dunkley: Andrew, well done.

576
00:24:08.050 --> 00:24:09.210
Professor Fred Watson: You should be on the I try

577
00:24:09.210 --> 00:24:11.410
Andrew Dunkley: to think on 11 year old level, but I'm

578
00:24:11.410 --> 00:24:13.290
thinking Thomas was probably much brighter at

579
00:24:13.290 --> 00:24:15.770
11 than I was struggle

580
00:24:15.770 --> 00:24:17.250
Professor Fred Watson: to get to 11. So do I.

581
00:24:17.570 --> 00:24:20.370
Andrew Dunkley: Yes, thanks Thomas. That was really terrific.

582
00:24:20.370 --> 00:24:22.290
Thanks for sending it in and uh, keep on

583
00:24:22.290 --> 00:24:22.850
listening.

584
00:24:26.930 --> 00:24:29.810
Professor Fred Watson: Tranquilly Base here. The eagle has landed.

585
00:24:29.810 --> 00:24:30.850
Professor Fred Watson: Space nets.

586
00:24:31.330 --> 00:24:34.240
Andrew Dunkley: Final question, Fred Watson, comes from Paul.

587
00:24:35.040 --> 00:24:36.880
Joe: Hello, Space Nights. Paul here from

588
00:24:36.880 --> 00:24:38.400
Sunnybris, Vegas, where it's currently

589
00:24:38.480 --> 00:24:41.400
bucketing down in what is being described

590
00:24:41.400 --> 00:24:44.000
as a rare rain occurrence.

591
00:24:45.200 --> 00:24:47.440
Anyway, I

592
00:24:48.320 --> 00:24:51.080
am currently looking through a very old book

593
00:24:51.080 --> 00:24:54.080
of mine. Guess it's old compared to

594
00:24:54.080 --> 00:24:56.840
these students I teach. It was published back

595
00:24:56.840 --> 00:24:59.840
in 1978. I think I got it in 1980 from

596
00:25:00.450 --> 00:25:02.600
uh, an uncle of mine, Uncle Jim. Thank you

597
00:25:02.600 --> 00:25:04.560
very much. It's called Stars and Planets and

598
00:25:04.560 --> 00:25:06.380
it's probably what got me into

599
00:25:07.340 --> 00:25:10.020
the whole field of astronomy in the first

600
00:25:10.020 --> 00:25:12.940
place. At least my interest in astronomy.

601
00:25:12.940 --> 00:25:13.740
Obviously

602
00:25:15.980 --> 00:25:17.100
Andrew Dunkley: very, uh, very grateful.

603
00:25:17.500 --> 00:25:20.140
Joe: I'm on the page where it's talking about

604
00:25:20.220 --> 00:25:22.620
how the American astronomer Carlo

605
00:25:22.620 --> 00:25:25.180
Shapley used

606
00:25:25.260 --> 00:25:28.260
the 1.5 metre reflector on

607
00:25:28.260 --> 00:25:30.540
top of Matt Wilson in California

608
00:25:31.830 --> 00:25:34.470
to work out that our sun is

609
00:25:34.790 --> 00:25:36.950
not at the centre of our galaxy. As was

610
00:25:36.950 --> 00:25:39.510
previously thought, but is about two thirds

611
00:25:39.510 --> 00:25:42.430
of the way to the edge. Could you

612
00:25:42.430 --> 00:25:45.430
please give us some idea how

613
00:25:45.430 --> 00:25:47.750
he actually managed to do that?

614
00:25:48.630 --> 00:25:50.990
Was it something about the

615
00:25:50.990 --> 00:25:53.670
density of stars? I mean, how many

616
00:25:53.670 --> 00:25:55.910
stars in the field of view?

617
00:25:56.370 --> 00:25:57.470
Andrew Dunkley: Uh, when you point it one way

618
00:25:57.470 --> 00:25:59.660
Joe: compared to the other other. How did you do

619
00:25:59.660 --> 00:26:01.940
it? I'm really curious and I know I could

620
00:26:01.940 --> 00:26:04.300
Google it, but I'd rather hear it from you

621
00:26:04.300 --> 00:26:07.220
guys. So thanks in advance. Love

622
00:26:07.220 --> 00:26:10.180
the show and dare I

623
00:26:10.180 --> 00:26:12.820
say, keep up the good work. Cheers.

624
00:26:13.380 --> 00:26:13.860
Professor Fred Watson: Cheers.

625
00:26:13.860 --> 00:26:15.840
Andrew Dunkley: Paul, thanks for sending that in. Uh,

626
00:26:16.900 --> 00:26:18.980
sending the question in and uh, we don't know

627
00:26:18.980 --> 00:26:21.820
the answer, so. But

628
00:26:21.820 --> 00:26:24.600
we're going to Google it. No, um, uh,

629
00:26:24.600 --> 00:26:26.920
1978, stars and planets. Uh,

630
00:26:27.520 --> 00:26:29.760
I tried to look it up. There are umpteen

631
00:26:29.840 --> 00:26:31.680
books named Stars and Planets.

632
00:26:31.680 --> 00:26:32.160
Professor Fred Watson: Yeah.

633
00:26:32.160 --> 00:26:34.280
Andrew Dunkley: So I haven't been able to, you know,

634
00:26:34.280 --> 00:26:36.600
distinguish one from the other as yet. So,

635
00:26:36.600 --> 00:26:39.560
um. Uh, yeah, you'll have to do some

636
00:26:39.560 --> 00:26:41.720
fishing to find the book that, uh, Paul was

637
00:26:41.720 --> 00:26:42.240
talking about.

638
00:26:42.240 --> 00:26:44.960
But he wanted to know about

639
00:26:45.280 --> 00:26:47.800
the man who decided or

640
00:26:47.800 --> 00:26:50.440
discovered that the sun was not the centre of

641
00:26:50.440 --> 00:26:53.320
everything. Uh, which was a common

642
00:26:53.320 --> 00:26:54.650
belief back in the day.

643
00:26:55.840 --> 00:26:58.400
Professor Fred Watson: It was, um, it was actually 1919 when that

644
00:26:58.400 --> 00:26:59.360
discovery was made.

645
00:27:00.000 --> 00:27:00.960
Andrew Dunkley: Was it that recent?

646
00:27:01.440 --> 00:27:04.440
Professor Fred Watson: Yeah. Wow. Uh, it's one of my favourite

647
00:27:04.440 --> 00:27:06.000
astronomical discoveries, which is why I

648
00:27:06.000 --> 00:27:08.080
didn't need to go to Google to look it up.

649
00:27:08.760 --> 00:27:11.440
Um, so it goes back to the time

650
00:27:11.520 --> 00:27:14.520
of William Herschel, uh, who was

651
00:27:14.520 --> 00:27:17.440
a German turned British

652
00:27:17.440 --> 00:27:20.360
astronomer, worked late in

653
00:27:20.360 --> 00:27:23.000
the 18th century and early in the 19th

654
00:27:23.000 --> 00:27:25.040
century, discovered the planet Uranus in

655
00:27:25.040 --> 00:27:27.900
1780. But what he was doing when

656
00:27:27.900 --> 00:27:30.420
he discovered Uranus was actually mapping the

657
00:27:30.420 --> 00:27:33.060
Milky Way. He was observing, um,

658
00:27:33.980 --> 00:27:36.780
the Milky Way in a very systematic way with a

659
00:27:36.780 --> 00:27:39.460
relatively small telescope. So sort of

660
00:27:39.460 --> 00:27:42.300
counting stars in the

661
00:27:42.300 --> 00:27:44.060
field of view of his telescope and then

662
00:27:44.060 --> 00:27:46.220
moving the telescope a bit further along the

663
00:27:46.220 --> 00:27:48.780
Milky Way, counting stars again, how many he

664
00:27:48.780 --> 00:27:51.420
could see in the field of view and doing that

665
00:27:51.420 --> 00:27:53.100
and doing it. He couldn't do it all the way

666
00:27:53.100 --> 00:27:54.700
around the Milky Way. Cause there's parts of

667
00:27:54.700 --> 00:27:56.460
it that he could never see because they're in

668
00:27:56.460 --> 00:27:58.840
the southern hemisphere. But he'd got round

669
00:27:58.840 --> 00:28:01.720
most of it. And what he discovered was that

670
00:28:02.520 --> 00:28:05.280
the star counts are pretty even all the way

671
00:28:05.280 --> 00:28:07.880
around. And so that led

672
00:28:08.440 --> 00:28:11.000
him to build the hypothesis that

673
00:28:11.240 --> 00:28:13.400
the stars are in a sort of flattened disc,

674
00:28:13.400 --> 00:28:16.120
which is correct. Uh, but that we're very

675
00:28:16.120 --> 00:28:18.120
near the middle, which is not correct.

676
00:28:18.760 --> 00:28:21.320
And the reason why he got that

677
00:28:21.320 --> 00:28:23.880
erroneous answer was that, uh, when you look

678
00:28:23.960 --> 00:28:26.180
through, I think it was a 7 inch telescope,

679
00:28:26.180 --> 00:28:28.940
if I remember right, a telescope of that

680
00:28:28.940 --> 00:28:31.380
size at, uh, the Milky Way, the stars that

681
00:28:31.380 --> 00:28:34.020
you see are all relatively

682
00:28:34.020 --> 00:28:36.820
nearby. They're perhaps 1000

683
00:28:36.820 --> 00:28:38.500
light years away or something like that,

684
00:28:38.500 --> 00:28:41.220
maybe a bit more, maybe a couple of thousand

685
00:28:41.220 --> 00:28:43.340
light years away in the plane of the Milky

686
00:28:43.340 --> 00:28:45.860
Way. And, uh, that's partly because the Milky

687
00:28:45.860 --> 00:28:48.540
Way is very dusty. Uh, there's a lot of dust

688
00:28:48.540 --> 00:28:50.660
everywhere. It's probably better described as

689
00:28:50.660 --> 00:28:53.140
smoke, but we call it dust in the world of

690
00:28:53.140 --> 00:28:55.940
astronomy. And so that dust limits how far

691
00:28:55.940 --> 00:28:58.480
you can see. And so when you look at the

692
00:28:58.480 --> 00:29:01.240
Milky Way, it does look generally relatively

693
00:29:01.240 --> 00:29:03.440
even. There's one bit in the constellation of

694
00:29:03.440 --> 00:29:06.000
Sagittarius where it's brighter and that's

695
00:29:06.000 --> 00:29:07.960
because you are looking towards, as we now

696
00:29:07.960 --> 00:29:10.760
know, the galactic centre. But, um, Herschel,

697
00:29:11.100 --> 00:29:13.240
um, he couldn't see that very well from the

698
00:29:13.240 --> 00:29:15.560
Northern hemisphere anyway. But he did sort

699
00:29:15.560 --> 00:29:18.440
of discount that. Uh, he said, by and large,

700
00:29:18.600 --> 00:29:21.520
it's the same count all the way around, so we

701
00:29:21.520 --> 00:29:24.440
must be in the middle, uh, roll

702
00:29:24.440 --> 00:29:27.240
on the years. And in 1919, Harlow

703
00:29:27.240 --> 00:29:29.640
Shapley, a very gifted American astronomer,

704
00:29:29.640 --> 00:29:31.520
although he did get one thing, one big thing

705
00:29:31.680 --> 00:29:34.480
wrong, uh, but what he did was

706
00:29:35.280 --> 00:29:37.160
he was interested in objects that we call

707
00:29:37.160 --> 00:29:39.639
globular clusters. And so these are, uh, in

708
00:29:39.639 --> 00:29:41.560
fact they were named by William Herschel. He

709
00:29:41.560 --> 00:29:43.640
gave them that name. Uh, clusters of stars

710
00:29:43.640 --> 00:29:46.400
that appear like a globe. Uh, and

711
00:29:47.600 --> 00:29:50.220
Harlow Shapley was, uh,

712
00:29:51.320 --> 00:29:53.560
he was interested in globular clusters. He

713
00:29:53.560 --> 00:29:56.280
noticed there were a lot of them in our, uh,

714
00:29:56.840 --> 00:29:59.840
skies. Uh, they tended

715
00:29:59.840 --> 00:30:02.320
to be different sizes. Uh,

716
00:30:02.680 --> 00:30:04.800
and he didn't know whether that was because

717
00:30:04.800 --> 00:30:06.400
they were all the same size and some were

718
00:30:06.400 --> 00:30:08.240
nearer than others or whether they were

719
00:30:08.240 --> 00:30:10.880
intrinsically different sizes. But what he

720
00:30:10.880 --> 00:30:13.320
did notice was that there's a concentration

721
00:30:13.400 --> 00:30:15.960
of them in the southern

722
00:30:15.960 --> 00:30:18.640
hemisphere sky. Uh, he was

723
00:30:18.640 --> 00:30:20.390
observing from California, so he could see,

724
00:30:20.540 --> 00:30:22.820
see a fair swath of the southern hemisphere

725
00:30:22.820 --> 00:30:25.540
sky. But he noticed that they were

726
00:30:25.540 --> 00:30:28.100
concentrated in that direction and that made

727
00:30:28.100 --> 00:30:30.940
him wonder if that

728
00:30:31.100 --> 00:30:33.180
was where the centre of the galaxy lay,

729
00:30:33.180 --> 00:30:36.130
rather than us being near the centre. Uh,

730
00:30:36.130 --> 00:30:38.980
but then his other step was that he

731
00:30:38.980 --> 00:30:41.580
recognised that within these globular

732
00:30:41.580 --> 00:30:44.540
clusters was something called, they

733
00:30:44.540 --> 00:30:47.380
called them cluster variables, stars that

734
00:30:47.380 --> 00:30:49.820
varied in a certain way with a

735
00:30:49.820 --> 00:30:52.720
periodicity of about a day. Uh, today

736
00:30:52.720 --> 00:30:55.040
we call them RR liry variables. And I

737
00:30:55.040 --> 00:30:56.760
actually started my astronomical research

738
00:30:56.840 --> 00:30:59.000
back in the 70s studying these things,

739
00:30:59.710 --> 00:31:02.360
uh, RR variables. Uh, and

740
00:31:03.720 --> 00:31:06.640
they are good because they've

741
00:31:06.640 --> 00:31:09.160
got basically a known distance.

742
00:31:09.710 --> 00:31:12.360
Uh, if you can see an RR

743
00:31:12.520 --> 00:31:15.400
variable and identify it as one, you know how

744
00:31:15.400 --> 00:31:18.360
intrinsically bright it is, uh, and then from

745
00:31:18.360 --> 00:31:20.920
that you can work out how far away it is.

746
00:31:21.240 --> 00:31:24.190
And so he found these variable stars in the

747
00:31:24.340 --> 00:31:27.180
globular clusters and recognised that he

748
00:31:27.180 --> 00:31:29.780
could draw a chart with the globular

749
00:31:29.780 --> 00:31:32.740
clusters all at their correct distance on it,

750
00:31:32.740 --> 00:31:35.340
make a kind of three dimensional map of the

751
00:31:35.340 --> 00:31:37.500
sky and sure enough, um, they

752
00:31:37.500 --> 00:31:40.220
concentrated around the galactic

753
00:31:40.220 --> 00:31:42.980
centre around a point. Uh, he actually got

754
00:31:42.980 --> 00:31:45.220
the answer wrong because his magnitude, his

755
00:31:45.220 --> 00:31:47.900
brightness that he had for the, uh, cluster

756
00:31:47.900 --> 00:31:50.860
variables was incorrect. And I can't remember

757
00:31:50.860 --> 00:31:53.530
what answer he got, but in my modern PARLANCE

758
00:31:54.090 --> 00:31:56.490
it's about 25,000 light years.

759
00:31:57.770 --> 00:32:00.370
The globular clusters themselves cluster

760
00:32:00.370 --> 00:32:03.290
around a point about 25,000 light years

761
00:32:03.290 --> 00:32:05.650
away, which is deeply hidden by the dust

762
00:32:05.650 --> 00:32:08.569
clouds in Sagittarius. So he

763
00:32:08.730 --> 00:32:10.490
figured out that that's where the centre of

764
00:32:10.490 --> 00:32:12.490
the galaxy was. A brilliant piece of

765
00:32:12.490 --> 00:32:15.320
detective work. We know he was right. Uh,

766
00:32:15.450 --> 00:32:18.250
what he was wrong about was, uh, he had a big

767
00:32:18.250 --> 00:32:21.210
discussion, I think in 1923,

768
00:32:21.690 --> 00:32:24.390
just before Hubble recogn that

769
00:32:24.390 --> 00:32:27.200
galaxies were big things a long way away. Uh,

770
00:32:27.200 --> 00:32:29.790
Shapley was arguing that galaxies lie within

771
00:32:29.790 --> 00:32:32.110
our own Milky Way, that they're small objects

772
00:32:32.110 --> 00:32:34.800
in our own Milky Way. And he was, um,

773
00:32:35.350 --> 00:32:37.550
arguing. It was a public debate actually,

774
00:32:37.550 --> 00:32:39.510
between Shapley and a guy called Heber

775
00:32:39.510 --> 00:32:42.270
Curtis. Uh, Curtis had the answer right. He

776
00:32:42.270 --> 00:32:44.550
said they're big and a long way off. Uh,

777
00:32:44.630 --> 00:32:46.950
Shapley said, no, they're small and nearby.

778
00:32:47.030 --> 00:32:49.230
And it was very soon after that that Hubble

779
00:32:49.230 --> 00:32:51.060
produced that they're big and a long way. Uh,

780
00:32:51.280 --> 00:32:53.150
uh, proved that they're big and a long way

781
00:32:53.150 --> 00:32:55.510
off. So Shapley was wrong in that, but he was

782
00:32:55.510 --> 00:32:57.010
right about galactic centre.

783
00:32:57.730 --> 00:33:00.450
Andrew Dunkley: Fantastic. Gee whiz. Um, great

784
00:33:00.450 --> 00:33:03.340
question, Paul. And, um, yeah, uh,

785
00:33:03.340 --> 00:33:05.650
if people are looking for that, uh, book

786
00:33:06.050 --> 00:33:08.780
Stars and Planets, uh, it is out there. Uh,

787
00:33:08.850 --> 00:33:11.010
look, I've found a couple that were actually

788
00:33:11.010 --> 00:33:13.330
published around that time that Paul

789
00:33:13.330 --> 00:33:15.770
mentioned, but not, um, sure if they're the

790
00:33:15.770 --> 00:33:18.390
ones. I can't remember the author now, um,

791
00:33:18.390 --> 00:33:19.690
that he said, but I don't think

792
00:33:19.690 --> 00:33:21.010
Professor Fred Watson: anyway, mentioned an author.

793
00:33:21.170 --> 00:33:22.930
Andrew Dunkley: I thought he did, but, uh, he might have

794
00:33:22.930 --> 00:33:23.250
mentioned it.

795
00:33:23.480 --> 00:33:23.880
Joe: Uncle.

796
00:33:24.200 --> 00:33:25.440
Professor Fred Watson: It was his uncle he mentioned.

797
00:33:25.440 --> 00:33:25.800
Andrew Dunkley: Uncle.

798
00:33:25.880 --> 00:33:26.680
Professor Fred Watson: Uncle Jim.

799
00:33:27.080 --> 00:33:28.630
Andrew Dunkley: Right. But, um,

800
00:33:30.340 --> 00:33:32.920
um, so, yeah, thanks, Paul. Thanks for the

801
00:33:32.920 --> 00:33:35.480
question. And, um, yeah, it's a fascinating,

802
00:33:35.600 --> 00:33:38.280
um, history in astronomy as we discover these

803
00:33:38.280 --> 00:33:40.040
things. I think one of my favourite

804
00:33:40.840 --> 00:33:43.800
moments, I suppose, in astronomical history

805
00:33:43.800 --> 00:33:46.640
was when they discovered that our sun was a

806
00:33:46.640 --> 00:33:46.920
star.

807
00:33:48.360 --> 00:33:50.920
Professor Fred Watson: M. That was a long time ago. Yeah,

808
00:33:51.200 --> 00:33:51.520
yeah.

809
00:33:51.600 --> 00:33:54.160
Andrew Dunkley: But for a while there we didn't think of It.

810
00:33:54.160 --> 00:33:55.440
Professor Fred Watson: I thought it was something else. That's

811
00:33:55.440 --> 00:33:58.240
right. Something a bit special. Yeah.

812
00:33:58.580 --> 00:34:01.520
Andrew Dunkley: Um, and I saw that on a BBC documentary

813
00:34:01.520 --> 00:34:03.200
many years ago and I sat there and went,

814
00:34:04.240 --> 00:34:06.560
wow. I never thought about that because I've

815
00:34:06.560 --> 00:34:09.040
always known it to be a star, but for

816
00:34:09.360 --> 00:34:10.960
generations they didn't.

817
00:34:12.880 --> 00:34:15.320
Quite intriguing. And why would you. It

818
00:34:15.320 --> 00:34:16.480
doesn't look like a star.

819
00:34:17.440 --> 00:34:20.380
Professor Fred Watson: That's right. Uh, uh, it's

820
00:34:20.380 --> 00:34:22.179
clearly quite different from a star. Uh,

821
00:34:23.980 --> 00:34:24.580
Andrew Dunkley: incredible.

822
00:34:24.580 --> 00:34:26.380
Thanks, Paul. Thanks for sending that in. And

823
00:34:26.380 --> 00:34:29.140
if you have a question for. Thanks to all our

824
00:34:29.140 --> 00:34:31.500
sender innerers, I've always wanted to say

825
00:34:31.500 --> 00:34:33.420
that, uh, for their questions. And if you

826
00:34:33.420 --> 00:34:34.860
would like to send a question, go to our

827
00:34:34.860 --> 00:34:37.300
website, spacenutspodcast.com or

828
00:34:37.300 --> 00:34:40.220
spacenuts IO and there's a little

829
00:34:40.220 --> 00:34:43.020
AMA M tab at the top, which stands for Ask

830
00:34:43.020 --> 00:34:45.380
me anything. Not me personally, it's the

831
00:34:45.380 --> 00:34:48.349
rookie royal me. And, um,

832
00:34:48.570 --> 00:34:50.770
just put your, uh, question in there. It can

833
00:34:50.770 --> 00:34:53.090
be text or audio. Don't forget to tell us who

834
00:34:53.090 --> 00:34:54.530
you are and where you're from and have a look

835
00:34:54.530 --> 00:34:56.250
around. While you're there, don't forget to

836
00:34:56.250 --> 00:34:59.210
leave a review at your favourite podcasting

837
00:34:59.370 --> 00:35:01.130
platform. We're all done. Thanks,

838
00:35:01.130 --> 00:35:01.530
Fred Watson.

839
00:35:02.010 --> 00:35:04.930
Professor Fred Watson: A great pleasure, Andrew. Um, we, uh,

840
00:35:04.930 --> 00:35:07.530
continue to get great questions from great

841
00:35:07.530 --> 00:35:09.770
listeners and long may it continue. Thank

842
00:35:09.770 --> 00:35:09.930
you.

843
00:35:09.930 --> 00:35:12.630
Andrew Dunkley: Yes, indeed, we continue to solve and evolve.

844
00:35:13.830 --> 00:35:14.940
Um, maybe not.

845
00:35:15.260 --> 00:35:16.220
Professor Fred Watson: I'm not evolving.

846
00:35:18.220 --> 00:35:21.180
Andrew Dunkley: Once you reach a certain age, evolving

847
00:35:21.180 --> 00:35:23.500
just is not part of the programme. That's

848
00:35:23.500 --> 00:35:23.820
right.

849
00:35:23.900 --> 00:35:24.380
Professor Fred Watson: Yeah.

850
00:35:24.460 --> 00:35:26.860
Andrew Dunkley: Ask my mum on the Internet. Uh, thanks,

851
00:35:26.860 --> 00:35:27.900
Fred Watson. We'll see you soon.

852
00:35:28.300 --> 00:35:29.740
Professor Fred Watson: Sounds great. Thanks, Andrea.

853
00:35:29.740 --> 00:35:31.380
Andrew Dunkley: Professor Fred Watson Watson, astronomer at

854
00:35:31.380 --> 00:35:33.140
large. And thanks to Huw in the studio. He's

855
00:35:33.140 --> 00:35:35.940
just turned up. Um, we started 39

856
00:35:35.940 --> 00:35:38.740
minutes ago and, um, Huw set his

857
00:35:38.740 --> 00:35:41.380
clock to a Martian day, so that's why he's

858
00:35:41.380 --> 00:35:42.270
39 minutes late.

859
00:35:42.820 --> 00:35:43.380
Professor Fred Watson: Boom, boom.

860
00:35:43.460 --> 00:35:45.260
Andrew Dunkley: And from me, Andrew Dunkley, thanks for your

861
00:35:45.260 --> 00:35:47.380
company. We'll see you on the next episode of

862
00:35:47.380 --> 00:35:48.100
Space Nuts.

863
00:35:48.100 --> 00:35:48.740
Professor Fred Watson: Bye. Bye.

864
00:35:49.780 --> 00:35:52.060
Joe: You've been listening to the Space Nuts

865
00:35:52.060 --> 00:35:55.020
Andrew Dunkley: podcast, available at

866
00:35:55.020 --> 00:35:56.980
Apple Podcasts, Spotify,

867
00:35:57.140 --> 00:35:59.900
iHeartRadio or your favourite podcast

868
00:35:59.900 --> 00:36:01.620
player. You can also stream on

869
00:36:01.620 --> 00:36:04.620
demand@bytes.com. this has been another

870
00:36:04.620 --> 00:36:06.700
quality podcast production from

871
00:36:06.700 --> 00:36:07.860
bytes.com.