1 00:00:26,830 --> 00:00:32,286 At the base of everything lie the eternal questions of origins. 2 00:00:32,286 --> 00:00:34,496 These are questions that priests, 3 00:00:34,496 --> 00:00:38,462 philosophers along with us scientists, have all examined. 4 00:00:39,462 --> 00:00:43,564 We research extrasolar planets to find the origins of life, 5 00:00:43,564 --> 00:00:46,661 and for the origins of the Universe… 6 00:00:46,661 --> 00:00:49,362 we try to observe the Universe in its infancy. 7 00:00:51,467 --> 00:00:55,900 And that’s the main motivation for building bigger and better telescopes 8 00:00:55,900 --> 00:00:58,521 and ever more sophisticated instruments. 9 00:01:17,440 --> 00:01:21,792 Even though light travels at 300 000 kilometres per second, 10 00:01:21,792 --> 00:01:26,283 the Universe is so vast that light from celestial objects 11 00:01:26,283 --> 00:01:28,484 takes a long time to reach us. 12 00:01:30,895 --> 00:01:35,744 The Sun’s light takes eight minutes to traverse the 150 million kilometres 13 00:01:35,744 --> 00:01:38,098 between the Sun and the Earth, 14 00:01:38,098 --> 00:01:43,325 while light from the closest star, Proxima Centauri, takes four years. 15 00:01:45,019 --> 00:01:50,155 Our neighbouring galaxy Andromeda, is 2.5 million light-years away, 16 00:01:50,155 --> 00:01:53,164 meaning that when we look at the Andromeda Galaxy, 17 00:01:53,164 --> 00:01:56,895 we see it as it was more than 2 million years ago. 18 00:01:57,992 --> 00:02:01,573 By attempting to observe even more distant galaxies, 19 00:02:01,573 --> 00:02:03,853 nearly 13 billion light-years away, 20 00:02:03,853 --> 00:02:08,763 we can go back in time to approach the birth of the Universe. 21 00:02:12,471 --> 00:02:14,519 Astronomers are contemplative. 22 00:02:14,682 --> 00:02:17,354 The only thing we can observe is light. 23 00:02:17,419 --> 00:02:21,889 Actually, we would rather do experiments like in other sciences… 24 00:02:21,889 --> 00:02:26,541 weigh a galaxy for instance, or stop it from turning to see what happens, 25 00:02:26,541 --> 00:02:28,387 but of course, we can't do that. 26 00:02:28,387 --> 00:02:32,198 Our one and only source of information is light. 27 00:02:38,200 --> 00:02:43,312 Of course, we can take pictures, look at the shape of objects, 28 00:02:43,312 --> 00:02:44,936 and see their colours, 29 00:02:44,936 --> 00:02:47,097 but because light transmits information 30 00:02:47,097 --> 00:02:49,529 about the atoms that emitted it, 31 00:02:49,529 --> 00:02:53,654 by using quanta of energy or quantum mechanics 32 00:02:53,654 --> 00:02:56,192 we can do much more than that. 33 00:02:58,225 --> 00:03:02,373 We can find the signature of those atoms, a sort of unique genetic code, 34 00:03:02,373 --> 00:03:04,338 and that’s really powerful, 35 00:03:04,338 --> 00:03:07,670 as it means we can determine the chemical composition, 36 00:03:07,670 --> 00:03:12,063 the physics of the gas, even the movements of the stars, 37 00:03:12,063 --> 00:03:14,298 thanks to the Doppler effect. 38 00:03:16,147 --> 00:03:20,567 The instruments that enable us to obtain information by analysing light 39 00:03:20,567 --> 00:03:25,548 are called spectrographs, and they are absolutely essential to us. 40 00:03:30,246 --> 00:03:32,169 Since its invention in the 19th century, 41 00:03:32,169 --> 00:03:35,326 the spectrograph has been a fundamental tool in astronomy. 42 00:03:35,326 --> 00:03:37,859 In the 1990s, a new type of instrument 43 00:03:38,094 --> 00:03:42,176 was invented in Europe: the 3D, or integral field spectrograph. 44 00:03:42,176 --> 00:03:46,409 For the first time, we could obtain spectra of a wide area of the sky, 45 00:03:46,409 --> 00:03:49,064 containing many astronomical objects. 46 00:03:49,064 --> 00:03:51,897 The first generation of instruments based on this new concept 47 00:03:51,897 --> 00:03:54,907 is now installed on large telescopes around the world. 48 00:03:54,907 --> 00:03:57,493 With its many telescopes in Chile, 49 00:03:57,493 --> 00:03:59,769 the European Southern Observatory, or ESO, 50 00:03:59,769 --> 00:04:02,183 is the spearhead of European astronomy. 51 00:04:02,183 --> 00:04:06,175 Many examples of first generation 3D spectrographs 52 00:04:06,175 --> 00:04:10,057 are already in place at the focus of the four Very Large Telescopes, 53 00:04:10,057 --> 00:04:14,450 with 8.2-metre diameter mirrors, at Paranal Observatory. 54 00:04:18,161 --> 00:04:21,482 As technology advances, after say ten years, 55 00:04:21,482 --> 00:04:25,540 you can build a much better camera or a much better spectrograph 56 00:04:25,540 --> 00:04:28,189 and put it on a telescope and make it more powerful, 57 00:04:28,189 --> 00:04:30,951 but it takes five to ten years to do. 58 00:04:30,951 --> 00:04:33,434 So early 2000s, 59 00:04:33,434 --> 00:04:39,971 planning was going on at ESO — we should have ideas for new, 60 00:04:39,971 --> 00:04:43,556 more powerful instruments, called second generation instruments. 61 00:04:45,989 --> 00:04:50,873 ESO’s tender immediately gave us a chance to move up a gear, 62 00:04:50,873 --> 00:04:54,048 and to propose something that was based on 63 00:04:54,048 --> 00:04:57,438 everything we had learned during all those years, 64 00:04:57,438 --> 00:04:59,439 something much more ambitious, 65 00:04:59,439 --> 00:05:02,439 which would mean we’d be able to observe 66 00:05:02,439 --> 00:05:05,372 the very distant Universe like never before, 67 00:05:05,372 --> 00:05:08,883 and so that was the very beginning of the MUSE project. 68 00:05:13,067 --> 00:05:18,709 In the past, we did have instruments that in a way operate like MUSE 69 00:05:18,709 --> 00:05:20,523 — integral field spectrographs, 70 00:05:20,523 --> 00:05:23,141 they make images and spectra at the same time, 71 00:05:23,141 --> 00:05:25,494 they have been around for 20 years, 72 00:05:25,494 --> 00:05:30,196 and both in Lyon and also our institute in Potsdam 73 00:05:30,196 --> 00:05:34,781 have been very successful in using these types of observations. 74 00:05:34,781 --> 00:05:38,827 But what MUSE now really for the first time introduces 75 00:05:38,827 --> 00:05:41,659 is to combine this capability 76 00:05:41,659 --> 00:05:45,382 with the capability of the survey instrument, 77 00:05:45,382 --> 00:05:49,352 meaning really to look at a significant part of the sky, 78 00:05:49,352 --> 00:05:51,704 not just at one galaxy, 79 00:05:51,704 --> 00:05:56,553 but really at a significant part of the sky and have lots of stuff in there, 80 00:05:56,553 --> 00:06:03,035 and everything with this imaging plus spectroscopy capability. 81 00:06:03,035 --> 00:06:06,553 That’s a very new approach to do astronomy. 82 00:06:07,553 --> 00:06:11,078 MUSE, the Multi-Unit Spectroscopic Explorer, 83 00:06:11,078 --> 00:06:15,206 is composed of not just one 3D spectrograph, but 24. 84 00:06:15,206 --> 00:06:17,138 When the light of the galaxy 85 00:06:17,138 --> 00:06:19,160 captured by the telescope enters the instrument, 86 00:06:19,160 --> 00:06:22,844 the first optical element the light encounters is the de-rotator, 87 00:06:22,844 --> 00:06:24,953 which compensates for the Earth’s rotation. 88 00:06:25,621 --> 00:06:29,053 The stabilised image is then magnified by a pair of mirrors. 89 00:06:29,053 --> 00:06:32,551 Next, the beam enters the first field-splitter. 90 00:06:32,551 --> 00:06:36,209 The image of the galaxy is split into 24 sections, 91 00:06:36,209 --> 00:06:38,717 resulting in 24 separate optical beams. 92 00:06:39,931 --> 00:06:41,954 These beams are distributed by a group of 93 00:06:41,954 --> 00:06:44,677 mirrors and lenses to the 24 modules. 94 00:06:47,003 --> 00:06:50,319 The light is again split by a second field-splitter, 95 00:06:50,319 --> 00:06:53,672 called a slicer — the masterpiece of MUSE. 96 00:06:53,672 --> 00:06:57,630 The slicer is composed of two series of 48 spherical mirrors, 97 00:06:57,630 --> 00:07:00,269 which split the beam into 48 slices. 98 00:07:00,269 --> 00:07:04,681 The light reflected by each small mirror enters the spectrograph, 99 00:07:05,044 --> 00:07:07,606 where it is dispersed according to its wavelength. 100 00:07:07,606 --> 00:07:12,079 The detector registers the spectrum of a small part of the galaxy. 101 00:07:12,079 --> 00:07:15,572 This process is repeated for each of the 48 beams. 102 00:07:15,572 --> 00:07:19,032 The detector is then completely illuminated. 103 00:07:19,032 --> 00:07:21,000 The same thing occurs simultaneously 104 00:07:21,000 --> 00:07:23,512 in each of the 24 spectrographs. 105 00:07:23,512 --> 00:07:26,260 The resulting 400-million-pixel image 106 00:07:26,260 --> 00:07:30,091 holds the spectral information of every part of the galaxy. 107 00:07:31,756 --> 00:07:34,797 Obviously, no laboratory could take on a project 108 00:07:34,797 --> 00:07:36,983 as complex as MUSE alone, 109 00:07:36,983 --> 00:07:40,036 no one would have had the strength or capacity for that, 110 00:07:40,036 --> 00:07:43,482 so I brought together a group of laboratories in Europe which, 111 00:07:43,482 --> 00:07:46,241 together, had the expertise for such a project. 112 00:07:47,370 --> 00:07:50,108 Five research laboratories joined 113 00:07:50,108 --> 00:07:52,124 the Astrophysical Research Centre of Lyon 114 00:07:52,124 --> 00:07:54,373 to develop MUSE, along with ESO. 115 00:07:57,942 --> 00:08:02,526 The process began in 2004 with the conceptualisation, design, 116 00:08:02,526 --> 00:08:05,086 and construction involving experts in 117 00:08:05,086 --> 00:08:08,146 optics, mechanics, electronics and software. 118 00:08:10,382 --> 00:08:15,151 The different phases took 9 years and involved a hundred researchers, 119 00:08:15,151 --> 00:08:18,526 technicians and engineers to overcome the many challenges, 120 00:08:18,526 --> 00:08:21,032 particularly in the development of the slicer, 121 00:08:21,032 --> 00:08:22,910 the key component of MUSE. 122 00:08:25,025 --> 00:08:28,355 So you have to understand, that in the beginning, 123 00:08:28,355 --> 00:08:31,424 when we launched the project, as is often the case, 124 00:08:31,424 --> 00:08:34,222 we didn’t actually know how to create this slicer. 125 00:08:34,222 --> 00:08:37,334 We’d made a small prototype, but that’s all, 126 00:08:37,334 --> 00:08:39,184 and so as the project went on, 127 00:08:39,184 --> 00:08:41,654 we had to demonstrate that we could in fact do it. 128 00:08:41,654 --> 00:08:44,585 So we launched a whole load of tests, 129 00:08:44,585 --> 00:08:47,788 made a whole load of things in metal, with different technologies, 130 00:08:47,788 --> 00:08:50,604 in the optical field, with a variety of manufacturers, 131 00:08:50,604 --> 00:08:52,439 in Europe, and in the USA… 132 00:08:52,439 --> 00:08:54,679 and each time, it didn't function. 133 00:08:54,679 --> 00:08:58,293 Each time there was something that didn’t work, and so at one point, 134 00:08:58,293 --> 00:09:00,849 we really thought that the project would have to stop there 135 00:09:00,849 --> 00:09:02,388 — no slicers, no MUSE. 136 00:09:02,988 --> 00:09:06,710 And then suddenly, a French manufacturer 137 00:09:06,710 --> 00:09:07,719 came up with technology 138 00:09:07,719 --> 00:09:11,024 that meant we could finally create the slicer, 139 00:09:11,024 --> 00:09:15,301 and of course there wasn’t just one, but 24 to be made! 140 00:09:15,301 --> 00:09:18,184 We were saved. 141 00:09:26,381 --> 00:09:29,756 The assembly of MUSE began in Lyon in 2010. 142 00:09:29,756 --> 00:09:33,555 Thousands of components arrived from all over Europe. 143 00:09:36,323 --> 00:09:37,933 It took three years to assemble, 144 00:09:37,933 --> 00:09:41,990 calibrate, align and test the instrument. 145 00:10:23,575 --> 00:10:29,571 In September 2013, after final tests, MUSE was disassembled, 146 00:10:29,571 --> 00:10:32,018 carefully packed, and shipped to Chile. 147 00:11:00,271 --> 00:11:02,919 MUSE arrived in dozens and dozens of boxes. 148 00:11:02,919 --> 00:11:07,644 Several lorry loads arrived in Paranal, and our first concern was: 149 00:11:07,644 --> 00:11:10,020 had everything arrived in one piece? 150 00:11:10,020 --> 00:11:12,567 Because you see, they are unique pieces, 151 00:11:12,567 --> 00:11:14,687 and if one part had been broken, 152 00:11:14,687 --> 00:11:17,686 there wouldn’t have been time to make another one quickly enough, 153 00:11:17,686 --> 00:11:20,405 so that was already very stressful. 154 00:11:20,405 --> 00:11:21,847 But everything was fine, 155 00:11:21,847 --> 00:11:23,506 and so once all the crates 156 00:11:23,506 --> 00:11:25,856 with all the pieces had been unpacked at Paranal, 157 00:11:25,856 --> 00:11:29,316 and we saw that everything was alright, it had to be assembled, 158 00:11:29,316 --> 00:11:32,537 tested and aligned; and for MUSE, 159 00:11:32,537 --> 00:11:35,882 which is one of the biggest instruments to install on the VLT 160 00:11:35,882 --> 00:11:39,268 — the biggest, in fact — that phase took a long time. 161 00:11:40,972 --> 00:11:42,861 But the really stressful part of this marathon 162 00:11:42,861 --> 00:11:44,569 was respecting the deadlines. 163 00:11:44,569 --> 00:11:49,225 The nights that had been allotted to us for the commissioning on the sky 164 00:11:49,225 --> 00:11:51,658 had been fixed a long time in advance, 165 00:11:51,658 --> 00:11:54,007 and we absolutely could not miss them. 166 00:11:57,567 --> 00:12:00,968 That was a new experience for us, because in earlier projects, 167 00:12:00,968 --> 00:12:03,565 we had disassembled instruments, 168 00:12:03,565 --> 00:12:07,710 put them into single pieces and reassembled them again, 169 00:12:07,710 --> 00:12:09,785 on the telescope on the platform, 170 00:12:09,785 --> 00:12:13,342 but for MUSE it turned out it’s not feasible, 171 00:12:13,342 --> 00:12:18,116 because MUSE was too complicated to do all this assembly 172 00:12:18,116 --> 00:12:22,904 and especially these alignments inside of the telescope dome. 173 00:12:25,473 --> 00:12:29,808 It was decided that we will lift the instrument as a total 174 00:12:29,808 --> 00:12:32,455 in the single lift into the dome, 175 00:12:32,455 --> 00:12:37,776 and there is only one way to enter the dome with a big-sized instrument, 176 00:12:37,776 --> 00:12:41,049 and that is the slit for observation. 177 00:12:44,287 --> 00:12:46,998 Imagine our state of mind beforehand… 178 00:12:47,098 --> 00:12:50,999 We knew that it was the crucial part of the operation 179 00:12:50,999 --> 00:12:54,651 and that the weather would play a key role in it being successful, 180 00:12:54,651 --> 00:12:57,746 since we were going to unpack the instrument 181 00:12:57,746 --> 00:13:01,438 and leave it outside before installing it in the telescope. 182 00:13:01,438 --> 00:13:05,128 But of course, just as we were about to do this, 183 00:13:05,128 --> 00:13:07,725 there was high wind and risk of rain. 184 00:13:07,725 --> 00:13:10,235 So we slowed down a bit, and waited, 185 00:13:10,235 --> 00:13:13,611 and then we had a meeting and looked at the weather forecast, 186 00:13:13,611 --> 00:13:15,587 and made the decision to go ahead. 187 00:13:40,915 --> 00:13:44,298 One of the biggest risks was, of course, 188 00:13:44,298 --> 00:13:45,614 damage to the instrument. 189 00:13:45,614 --> 00:13:49,341 But there was also another parameter: the alignment. 190 00:13:49,341 --> 00:13:53,888 This had taken more than two months to do in the integration hall, 191 00:13:53,888 --> 00:13:57,972 and if it had become misaligned, 192 00:13:57,972 --> 00:14:01,294 we would have had no choice but to take it back down again. 193 00:14:05,517 --> 00:14:11,296 And then it was lifted up to fifteen metres elevation above our heads, 194 00:14:11,296 --> 00:14:14,116 but to be honest at that moment, 195 00:14:14,116 --> 00:14:17,549 I thought I would be totally excited 196 00:14:17,549 --> 00:14:22,245 and fear that the instrument could fall down… 197 00:14:28,967 --> 00:14:32,629 Another critical element was that the telescope has mirrors, 198 00:14:32,629 --> 00:14:35,898 and we would have had a big problem with the mirrors 199 00:14:35,898 --> 00:14:37,477 if the Sun shone on them, 200 00:14:37,477 --> 00:14:42,310 so we started lifting at around 5-5:30 am, 201 00:14:42,310 --> 00:14:44,167 and when we had finished, 202 00:14:44,167 --> 00:14:45,828 we only had about ten minutes 203 00:14:45,828 --> 00:14:47,991 before the Sun arrived on the main mirror, 204 00:14:47,991 --> 00:14:52,183 which was the moment when we absolutely had to close the shutter. 205 00:14:52,183 --> 00:14:56,242 So not only was it a very delicate technical operation, 206 00:14:56,242 --> 00:14:58,929 but one that had to be done in a very limited space of time. 207 00:15:34,501 --> 00:15:37,117 It was the first time that light, 208 00:15:37,117 --> 00:15:39,592 other than ambient light or from a calibration lamp, 209 00:15:39,592 --> 00:15:41,383 would reach the instrument… 210 00:15:41,383 --> 00:15:45,014 the light of a star or of a galaxy, for example. 211 00:15:48,088 --> 00:15:51,272 I wanted to symbolise that moment by choosing 212 00:15:51,272 --> 00:15:57,978 a special object that was hidden and secret, so I chose the Captain star. 213 00:15:57,978 --> 00:16:01,950 I chose it because it’s 13 light years away, 214 00:16:01,950 --> 00:16:05,858 which means that the light left this star in 2001, 215 00:16:05,858 --> 00:16:09,377 at the same time that we made the bid for ESO’s tender. 216 00:16:14,955 --> 00:16:15,983 For 13 years, 217 00:16:15,983 --> 00:16:18,281 the light had travelled across deep space 218 00:16:18,281 --> 00:16:20,592 at 300 000 kilometres per second, 219 00:16:20,592 --> 00:16:24,738 and arrived 13 years later in MUSE’s channel number 6. 220 00:16:28,607 --> 00:16:30,199 It was really amazingly symbolic. 221 00:16:33,774 --> 00:16:35,303 I shared this with the team when they asked me, 222 00:16:35,303 --> 00:16:38,020 and I also told them that it was because 223 00:16:38,020 --> 00:16:40,453 the light from the star had gone straight ahead, 224 00:16:40,453 --> 00:16:43,453 whereas for us it had been a bit less straightforward. 225 00:16:49,077 --> 00:16:50,822 It was the First Light 226 00:16:50,822 --> 00:16:53,781 and it was the first time that we’d taken a picture of the sky. 227 00:16:53,781 --> 00:16:56,609 Personally, I was under a lot of pressure, 228 00:16:56,609 --> 00:16:58,565 because we had installed the instrument 229 00:16:58,565 --> 00:17:02,058 and then spent a week aligning it correctly with the telescope, 230 00:17:02,058 --> 00:17:04,794 so when we took the first image, 231 00:17:04,794 --> 00:17:07,345 it was also validation that the instrument 232 00:17:07,683 --> 00:17:09,595 was exactly opposite the telescope. 233 00:17:14,563 --> 00:17:17,845 It was the result of ten years of work and it functioned, 234 00:17:17,845 --> 00:17:19,738 we could see our stars! 235 00:17:19,738 --> 00:17:23,646 They were clearly defined and we could put them in the right order. 236 00:17:23,646 --> 00:17:25,355 We had succeeded, 237 00:17:25,355 --> 00:17:29,042 so now we could hand this instrument over to the scientists, 238 00:17:29,042 --> 00:17:32,068 and we knew that they were going to have a lot of fun with it. 239 00:17:42,190 --> 00:17:45,843 MUSE was set up, but before entering service, 240 00:17:45,843 --> 00:17:48,435 it had to pass a battery of tests and adjustments. 241 00:17:48,435 --> 00:17:51,713 This stage, known as “commissioning”, 242 00:17:51,713 --> 00:17:53,796 required many nights of data acquisition 243 00:17:53,796 --> 00:17:55,838 so that the engineers and researchers 244 00:17:55,838 --> 00:17:58,709 could obtain MUSE’s optimal performance. 245 00:18:02,909 --> 00:18:04,627 On this screen, we can see 246 00:18:04,627 --> 00:18:09,033 the reconstructed image of the area of sky which is being observed. 247 00:18:09,033 --> 00:18:12,407 You can see the different objects that we have marked, 248 00:18:12,407 --> 00:18:14,873 and for each of the objects, 249 00:18:14,873 --> 00:18:18,294 you can see the spectra which gives us 250 00:18:18,294 --> 00:18:20,650 the characteristics and tells us what it is… 251 00:18:20,650 --> 00:18:25,128 if it’s a galaxy, or a quasar or another object of scientific interest. 252 00:18:28,461 --> 00:18:33,636 One of the big challenges of this project was being able to 253 00:18:33,636 --> 00:18:36,429 analyse efficiently the enormous amount of data 254 00:18:36,429 --> 00:18:38,259 that the instrument provides. 255 00:18:39,259 --> 00:18:43,605 You see, it’s capable of producing 400 million bytes of data a minute. 256 00:18:43,605 --> 00:18:46,776 The volume of information can be considerable, 257 00:18:46,776 --> 00:18:49,583 but it’s not only the volume, it’s also the complexity. 258 00:18:49,583 --> 00:18:51,965 The image that arrives on the detector 259 00:18:51,965 --> 00:18:54,929 has been cut several times into small pieces 260 00:18:54,929 --> 00:18:56,639 by slicers and by field splitters, 261 00:18:56,639 --> 00:19:02,065 and so it’s extremely complicated and you have to retrace algorithmically 262 00:19:02,065 --> 00:19:06,608 what happened on the detector and compare it to what was in the sky. 263 00:19:06,608 --> 00:19:13,089 What MUSE fundamentally creates is a lot of pixel data on some detectors, 264 00:19:13,089 --> 00:19:17,512 and if you look at that, you cannot make much head nor tail of it. 265 00:19:17,512 --> 00:19:20,082 So it’s a very complicated process. 266 00:19:20,082 --> 00:19:21,547 We have an expert in the team 267 00:19:21,547 --> 00:19:25,952 who wrote what we call the data reduction software, 268 00:19:25,952 --> 00:19:30,824 and that basically puts all these pixel data together to make 269 00:19:30,824 --> 00:19:34,599 images, spectra, the combined data cube, and so on. 270 00:19:37,632 --> 00:19:40,900 In February 2014, during the validation phase, 271 00:19:40,900 --> 00:19:43,275 MUSE observed the Orion Nebula 272 00:19:43,275 --> 00:19:46,561 to test its ability to analyse a large region of the sky. 273 00:19:46,561 --> 00:19:52,132 In less than two hours, MUSE took more than 60 pictures of the nebula 274 00:19:52,132 --> 00:19:54,418 — that is, two million spectra — 275 00:19:54,418 --> 00:19:59,333 100 times more than available so far. 276 00:19:59,333 --> 00:20:03,059 After processing, the data was arranged in a cube 277 00:20:03,059 --> 00:20:06,833 composed of a series of 4000 images of different wavelengths. 278 00:20:06,833 --> 00:20:13,659 The analysis of this data reveals a number of distinct chemical elements 279 00:20:13,659 --> 00:20:16,867 as well as the physical condition of the gas in the nebula. 280 00:20:16,867 --> 00:20:21,642 Compared to simple images, the data-cube produced by MUSE 281 00:20:21,642 --> 00:20:25,843 is so rich in information that researchers will need many months 282 00:20:25,843 --> 00:20:29,298 to fully analyse its contents and publish the results. 283 00:20:29,298 --> 00:20:31,149 So the real thing is, 284 00:20:31,149 --> 00:20:33,833 what we got with the Orion Nebula was really what we hoped for, 285 00:20:33,833 --> 00:20:36,115 even much better; it was so spectacular. 286 00:20:36,115 --> 00:20:41,469 Because there’s lots of gas, and that gas is in motion, 287 00:20:41,469 --> 00:20:47,120 and there are stars — hot stars — that excite this gas, 288 00:20:47,120 --> 00:20:50,801 that bring it to radiate in different parts 289 00:20:50,801 --> 00:20:52,547 of the electromagnetic spectrum. 290 00:20:52,547 --> 00:20:57,688 So you can easily visualise this with very colourful maps, 291 00:20:57,688 --> 00:21:01,543 and that’s what we did afterwards. 292 00:21:01,543 --> 00:21:05,528 And really, the interesting thing is that this was a showpiece 293 00:21:05,528 --> 00:21:08,694 of the capabilities of MUSE but it also contains 294 00:21:08,694 --> 00:21:13,756 an incredible richness of scientifically valuable data. 295 00:21:19,096 --> 00:21:21,113 Every 6 months, 296 00:21:21,113 --> 00:21:25,054 the members of the MUSE consortium meet for “busy weeks”. 297 00:21:25,054 --> 00:21:27,509 At these times, they report on the status 298 00:21:27,509 --> 00:21:31,183 of the observing program and discuss the latest results. 299 00:21:31,183 --> 00:21:35,833 Throughout the week, professors, postdocs and students 300 00:21:35,833 --> 00:21:39,065 of many nationalities come together with one objective: 301 00:21:39,065 --> 00:21:41,492 to extract scientific information 302 00:21:41,492 --> 00:21:44,528 from the light analysed and dissected by MUSE. 303 00:21:44,528 --> 00:21:47,737 Numerous topics are explored. 304 00:21:47,737 --> 00:21:53,643 In particular, my own interest is on how galaxies, 305 00:21:53,643 --> 00:21:58,024 like our own Milky Way Galaxy, how galaxies change with time, 306 00:21:58,024 --> 00:22:02,008 how they evolve, how they are formed in the early Universe, 307 00:22:02,008 --> 00:22:04,121 how they then develop over time, 308 00:22:04,121 --> 00:22:07,162 what controls how they develop, and so on. 309 00:22:07,162 --> 00:22:10,091 And we know that a key part of that 310 00:22:10,091 --> 00:22:14,340 is the interaction with gas in the Universe, 311 00:22:14,340 --> 00:22:22,316 how gas flows from the surrounding Universe onto the galaxy 312 00:22:22,316 --> 00:22:24,775 and that’s then the fuel out of which 313 00:22:24,775 --> 00:22:26,623 stars like the Sun are eventually made. 314 00:22:26,623 --> 00:22:32,865 And we know that surrounding galaxies, there is gas, 315 00:22:32,865 --> 00:22:35,726 it’s the gas left over if you like from the Big Bang. 316 00:22:35,726 --> 00:22:40,839 We see that in absorption against background objects, 317 00:22:40,839 --> 00:22:46,892 but that always just gives us a sort of one-dimensional probe. 318 00:22:46,892 --> 00:22:50,037 It’s literally like a needle through a haystack. 319 00:22:50,037 --> 00:22:54,298 With MUSE, we can actually now see where this gas is, 320 00:22:54,298 --> 00:22:57,865 in a sort of three dimensional volume. 321 00:22:57,865 --> 00:23:02,812 And so what we want to do with MUSE is to understand this process 322 00:23:02,812 --> 00:23:09,584 of how gas flows from the surrounding Universe onto galaxies. 323 00:23:13,564 --> 00:23:19,910 I would say holy grails of my own research field has been to detect 324 00:23:20,090 --> 00:23:26,001 this web of gas which we think must be there in the early Universe, 325 00:23:26,001 --> 00:23:28,968 out of which galaxies are forming. 326 00:23:28,968 --> 00:23:33,658 And MUSE really is the best instrument now 327 00:23:33,658 --> 00:23:35,667 to really try and see this. 328 00:23:42,874 --> 00:23:46,616 We observe quasars, so-called quasars, 329 00:23:46,616 --> 00:23:49,071 and these are some of the brightest sources in the Universe, 330 00:23:49,071 --> 00:23:51,930 and what the quasar is, is a supermassive black hole. 331 00:23:51,930 --> 00:23:53,675 Gas is spiraling in 332 00:23:53,675 --> 00:23:56,128 because of the gravity of the supermassive black hole, 333 00:23:56,128 --> 00:23:58,060 and because the gravity is so strong, 334 00:23:58,060 --> 00:24:01,350 the gas moves really really fast as it spirals into the black hole. 335 00:24:01,350 --> 00:24:03,250 And because it’s moving so fast, 336 00:24:03,250 --> 00:24:05,431 there’s a lot of friction between gas layers 337 00:24:05,431 --> 00:24:06,953 that are moving at different speeds, 338 00:24:06,953 --> 00:24:08,345 and the gas gets really really hot, 339 00:24:08,345 --> 00:24:11,751 and as it gets hot, it emits huge amounts of radiation. 340 00:24:11,751 --> 00:24:15,638 Now, we were using those quasars as tools, 341 00:24:15,638 --> 00:24:18,200 not to study them themselves, but as flashlights. 342 00:24:18,200 --> 00:24:21,144 Because they’re so bright you can see them all the way across the Universe, 343 00:24:21,144 --> 00:24:25,564 and you see a flashlight, and if you then check what the gas, 344 00:24:25,564 --> 00:24:29,665 on its way from the quasar to you — the telescope, the observer — 345 00:24:29,665 --> 00:24:33,682 what that gas around a galaxy that’s in between you absorbs, 346 00:24:33,682 --> 00:24:36,244 then you can learn about the gas around that galaxy, 347 00:24:36,244 --> 00:24:37,902 that you can’t observe in any other way. 348 00:24:38,902 --> 00:24:44,036 But, to learn how that relates to gas inflow and outflow of the galaxy, 349 00:24:44,036 --> 00:24:47,514 you need to know where the galaxy is, and that was the bottleneck. 350 00:24:47,514 --> 00:24:51,416 We couldn’t find the galaxies, only the very brightest ones. 351 00:24:51,416 --> 00:24:54,307 With MUSE we can go much fainter, 352 00:24:54,307 --> 00:24:56,391 one to two orders of magnitude fainter, 353 00:24:56,391 --> 00:24:58,035 so we can find many more galaxies. 354 00:24:58,035 --> 00:25:00,882 In fact, I realised we could find as many galaxies 355 00:25:00,882 --> 00:25:03,710 as we could see absorption lines, 356 00:25:03,710 --> 00:25:08,629 so we could really start to correlate the gas that we see in absorption 357 00:25:08,629 --> 00:25:10,788 with the galaxies detected by MUSE, 358 00:25:10,788 --> 00:25:13,030 and in that way, for the first time, 359 00:25:13,030 --> 00:25:15,774 learn about the gas inflows and outflows 360 00:25:15,774 --> 00:25:17,505 of galaxies that are far away. 361 00:25:17,505 --> 00:25:19,597 And these are important 362 00:25:19,597 --> 00:25:23,161 because far away in astronomy means further back in time. 363 00:25:25,033 --> 00:25:27,041 And with MUSE we can study this process at a time 364 00:25:27,041 --> 00:25:30,975 when galaxies were most active in the history of the Universe, 365 00:25:30,975 --> 00:25:33,330 and they were forming stars very vigorously, 366 00:25:33,330 --> 00:25:35,793 and because of that producing big explosions 367 00:25:35,793 --> 00:25:38,292 that blew a lot of gas back into intergalactic space. 368 00:25:48,170 --> 00:25:52,031 They do ice core drilling in Antarctica to go back in climate history, 369 00:25:52,031 --> 00:25:55,803 and it’s the same when we observe a sky zone very deeply. 370 00:25:55,803 --> 00:25:57,126 We go back in time. 371 00:25:57,126 --> 00:26:00,544 Now, I’m particularly interested in galaxies, 372 00:26:00,544 --> 00:26:02,804 those huge groups of millions of stars, 373 00:26:02,804 --> 00:26:05,933 and the millions of galaxies in the Universe. 374 00:26:05,933 --> 00:26:10,032 We want to know when they were formed, how they evolved, 375 00:26:10,032 --> 00:26:13,908 and so it’s like very deep core drilling of the Universe 376 00:26:13,908 --> 00:26:17,171 which means we can see galaxies at different ages 377 00:26:17,171 --> 00:26:21,075 — when they were infants, adolescents, adults, and so on… 378 00:26:21,075 --> 00:26:23,499 and that’s how we try and retrace their story. 379 00:26:23,499 --> 00:26:26,607 MUSE is really the perfect instrument for doing this. 380 00:26:26,607 --> 00:26:30,547 I think it’s brilliant, because I used to want to be an archaeologist, 381 00:26:30,547 --> 00:26:33,403 and I’ve rediscovered the love I had for it in my youth. 382 00:26:33,403 --> 00:26:36,326 With MUSE I’m doing the archaeology of the Universe! 383 00:26:38,939 --> 00:26:42,629 In 2014, over the equivalent of four nights, 384 00:26:42,629 --> 00:26:45,622 MUSE observed an area of the Hubble Deep Field. 385 00:26:47,471 --> 00:26:50,772 This field had previously been imaged in the year 2000 386 00:26:50,772 --> 00:26:52,489 by the Hubble Space Telescope, 387 00:26:52,489 --> 00:26:54,443 using very long exposures 388 00:26:54,443 --> 00:26:57,443 to obtain colour images of hundreds of galaxies. 389 00:27:01,243 --> 00:27:05,223 The MUSE data-cube of this field is rich in information. 390 00:27:05,923 --> 00:27:07,819 As we go through the cube, 391 00:27:07,819 --> 00:27:11,418 we advance in wavelength, from blue to infrared. 392 00:27:14,118 --> 00:27:16,460 A number of bright points can be seen, 393 00:27:16,460 --> 00:27:18,651 which vary in brightness with wavelength. 394 00:27:19,651 --> 00:27:21,452 These are mostly galaxies. 395 00:27:22,570 --> 00:27:24,311 From the brightness variations 396 00:27:24,311 --> 00:27:27,405 we can deduce the physical properties of the galaxies 397 00:27:27,405 --> 00:27:30,861 — for example, which types of stars are present there. 398 00:27:30,861 --> 00:27:36,023 We now select a small region of the data-cube; two zones to be precise. 399 00:27:36,023 --> 00:27:41,322 The first is the centre of a bright galaxy. The second is empty. 400 00:27:41,322 --> 00:27:44,430 On the left, we see a spectrum appear. 401 00:27:44,430 --> 00:27:49,108 Near 520 nanometres we encounter a bright emission line. 402 00:27:49,108 --> 00:27:52,216 The galaxy shines intensely at this wavelength, 403 00:27:52,216 --> 00:27:55,364 showing the presence of hot oxygen in the galaxy. 404 00:27:55,364 --> 00:28:01,986 In the red we suddenly see another line in the second part of the cube. 405 00:28:01,986 --> 00:28:05,744 There, where nothing was visible before, 406 00:28:05,744 --> 00:28:10,178 a galaxy is now revealed thanks to the presence of ionised hydrogen. 407 00:28:10,178 --> 00:28:14,026 By measuring the precise wavelength of the emission line, 408 00:28:14,026 --> 00:28:16,966 it’s possible to deduce the distance to the galaxy. 409 00:28:16,966 --> 00:28:21,353 It’s a very distant one – 13 billion light-years away, 410 00:28:21,353 --> 00:28:26,295 and we have observed it just one billion years after the Big Bang. 411 00:28:29,157 --> 00:28:32,145 The quality of the Hubble Telescope's image 412 00:28:32,145 --> 00:28:36,433 allows you to see a galaxy and its form with precision, 413 00:28:36,433 --> 00:28:38,476 but what you are essentially seeing 414 00:28:38,476 --> 00:28:42,561 is how much light is received at a given moment from that galaxy. 415 00:28:44,716 --> 00:28:49,151 With the spectra, you also have the distribution of the energy of this light, 416 00:28:49,151 --> 00:28:52,082 all its wavelengths and all its colours, 417 00:28:52,082 --> 00:28:56,338 and this provides a lot more information, 418 00:28:56,338 --> 00:28:59,526 like the speed at which these galaxies rotate, 419 00:28:59,526 --> 00:29:02,677 the movement of gas, chemical elements, 420 00:29:02,677 --> 00:29:07,155 and the number of stars of different ages — young and old — 421 00:29:07,155 --> 00:29:09,582 that the galaxies are composed of. 422 00:29:11,679 --> 00:29:15,089 All this information put together enables us to estimate 423 00:29:15,089 --> 00:29:17,894 what stage of development the galaxy has reached. 424 00:29:23,405 --> 00:29:26,548 Thanks to MUSE, we could measure the distances 425 00:29:26,548 --> 00:29:30,852 of something like 180 galaxies in the same field of vision, 426 00:29:30,852 --> 00:29:34,719 and we have discovered about 30 new very distant galaxies 427 00:29:34,719 --> 00:29:38,697 in that same field that couldn’t be seen with Hubble. 428 00:29:41,280 --> 00:29:44,313 We are aware that we have made a very beautiful instrument, 429 00:29:44,313 --> 00:29:46,592 which is now considered not only by us, 430 00:29:46,592 --> 00:29:49,100 but by the community of those who have really used it, 431 00:29:49,100 --> 00:29:51,116 to be the Rolls Royce of astronomy. 432 00:29:51,116 --> 00:29:55,271 After being used for a year, a remarkable number of articles 433 00:29:55,271 --> 00:29:57,894 have been published using data from it, 434 00:29:57,972 --> 00:30:00,761 mostly by people who were not on the MUSE team. 435 00:30:02,061 --> 00:30:06,013 It’s really great to see that people outside of the project 436 00:30:06,013 --> 00:30:08,800 can use this instrument easily, 437 00:30:08,800 --> 00:30:13,328 get results — and extremely good results — very quickly. 438 00:30:32,346 --> 00:30:37,636 In 2014, I lived through some truly extraordinary moments. 439 00:30:37,636 --> 00:30:44,417 It was like a dream come true; it was an idea, a vague plan that became, 440 00:30:44,417 --> 00:30:48,848 in reality, a fantastic machine to travel back in time. 441 00:30:51,800 --> 00:30:56,570 It was a technical, scientific and human adventure. 442 00:30:56,870 --> 00:30:59,964 Throughout it, I met some remarkable people, 443 00:30:59,964 --> 00:31:03,307 with remarkable intelligence devoted to the project, 444 00:31:03,307 --> 00:31:08,548 and together we made something extraordinary 445 00:31:08,548 --> 00:31:10,698 that none of us could have done alone. 446 00:31:13,741 --> 00:31:20,237 MUSE will be used by ESO and by us for maybe the next 10, 447 00:31:20,237 --> 00:31:22,300 15 or 20 years, 448 00:31:22,300 --> 00:31:25,012 so I think that MUSE will mark its era 449 00:31:25,012 --> 00:31:29,059 as an important contributor to scientific discovery.