Archive for the The Universe and Stuff Category

Back to Blighty

Posted in Biographical, The Universe and Stuff with tags , , on October 18, 2017 by telescoper

Just a brief post today to say that I got back safe and sound last night. I was up at 4am Tuesday Pune time (which was 11.30pm Monday UK time) and finally got to bed at about 11.30pm UK time last night, so apart from about 45 minutes doze on the flight I had been awake for 24 hours. Not surprisingly, I slept in this morning!

After another white-knuckle taxi ride (with the added complication of thick fog) I got Mumbai airport in good time. The flight itself was almost empty. Not only did I get a row of seats to myself in economy class, but the two rows in front in and the two rows behind were also unoccupied. I’m not entirely sure why the flight was so underbooked – as the outbound flight was absolutely crammed – but it may be that the festival of Diwali takes place this week (on Thursday or even today in some regions). Relatively few people are probably leaving India at this time compared with the many coming home to celebrate with friends and family. It’s a nice coincidence that Monday’s announcement of simultaneous detection of gravitational waves and electromagnetic radiation came so close to the Festival of Light, traditionally celebrated with fireworks and gifts of gold!

Despite liberal helpings of wine from the drinks trolley and the ability to lie down across three seats I still didn’t really sleep. I just don’t have the knack for sleeping on planes. Still, I did get to watch the film The Imitation Game which I hadn’t seen before and thought was very good.

We arrived back on schedule without the (usually) obligatory air traffic delays around Heathrow and, the arrivals hall being empty, I was out of the airport less than half an hour after landing. That’s a bit of record for me!

Anyway, I’ve various things to catch up on now that I’m back so I’ll try to get on with them. I’ll just end by thanking my hosts at IUCAA again for their hospitality and, while I’m at it, send a Happy Diwali message in Marathi to them and anyone else celebrating at this special time:

 

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GW News Day

Posted in The Universe and Stuff with tags , , on October 16, 2017 by telescoper

Well, it has certainly been an eventful last day in India!

Over a hundred people gathered at IUCAA to see this evening’s press conference, which basically confirmed most of the rumours that had been circulating that a Gamma Ray Burst had been detected in both GW and EM radiation. I won’t write in detail about today’s announcement because (a) a really useful page of resources has been prepared by the group at IUCAA. Check out the fact sheet and (b) I haven’t really had time to digest all the science yet.

I will mention a couple of things, however. One is that the signal-to-noise ratio of this detection is a whopping 32.4, a value that astronomers can usually only dream of! The other is that neutron star coalescence offer the possibility to bypass the traditional `distance ladder’ approaches to get an independent measurement of the Hubble constant. The value obtained is in the range 62 to 107 km s-1 Mpc-1, which is admittedly fairly broad, but is based on only one observation of this type. It is extremely impressive to be straddling the target with the very first salvo.

The LIGO collaboration is over a thousand people. Add to that the staff of no fewer than seventy observatories (including seven in space). With all that’s going in the world, it’s great to see what humans of different nations across the globe can do when they come together and work towards a common goal. Scientific results of this kind will remembered long after the silly ramblings of our politicians and other fools have been forgotten.

I took part in a panel discussion after the results were presented, but sadly I won’t be here to see tomorrow’s papers. I hope people will save cuttings or post weblinks if there are any articles!

UPDATE: Here is a selection of the local press coverage.

Indian LIGO

 

As if these thrilling science results weren’t enough I finally managed to meet my old friend and former collaborator Varun Sahni (who was away last week). An invitation to dinner at his house was not to be resisted on my last night here, which explains why I didn’t write a post immediately after the press conference. Still, of got plenty of papers to read on the plane tomorrow so maybe I’ll do something when I get back.

Tomorrow morning I get up early to return to Mumbai for the flight home, and am not likely to be online again until Wednesday UK time.

Thanks to all at IUCAA (and TIFR) for making my stay so pleasant and interesting. It’s been 23 years since I was last here. I hope it’s not so long before I’m back again!

Homes from Home in Pune

Posted in Biographical, History, The Universe and Stuff with tags , , , on October 16, 2017 by telescoper

Since I’m coming back tomorrow I thought I’d wander around this morning and take a few pictures of where I’ve been staying most of the last 10 days or so. First, this is a snap of the housing complex which contains my guest apartment.

I’m actually in the first building on the right. Here is the front door.

The faculty at both IUCAA (Pune) and TFIR (Mumbai) live in housing areas provided by their respective institutions, so they form quite a close-knit community. Some of the senior staff in IUCAA are housed just round the corner from my place.

IUCAA is on the Pune University Campus (except that it has its own entrance from the main road that runs along the Northern edge of the campus, where there is a security post. There are a few of these around the IUCAA site itself, so it is very secure and quite private. The campus is large with many tree-lined roads. At its heart, on a small hill, you can find this building:

This is (or was) the Raj Bhavan (`Government House’) and it was essentially the Governor of Maharashtra’s residence during the Monsoon season. Built in 1866, it was a sort of home-from-home when Bombay (the state capital) became too unbearable.

When I was last here in 1994, this was the Main Building of the University and was quite busy. Now, however, it seems to be disused and is in a state of some disrepair, the gardens also need a bit of love and attention. There are many new buildings around the University of Pune campus (including a modern administration block nearby). Since this building is a relic of the old colonial days it may be that it will be demolished to make way for something that better suits modern India. By the way, there’s a stone slab just next to the site of this building that displays the preamble to the Constitution of India, as adopted in 1949.

Anyway, this afternoon and evening promise to be quite busy. There is a press conference at IUCAA at 6.30pm about the gravitational waves discovery I mentioned a few days ago. There will be presentations before a viewing of the live feed from Washington DC then there’ll be a panel answering questions from the press. They’ve asked me to be on the panel, so I might appear in the India media, but as I’m leaving first thing tomorrow morning I probably won’t see any of the coverage!

Gravitational Waves Flash!

Posted in The Universe and Stuff with tags , , , , on October 13, 2017 by telescoper

I got up early this morning to hitch a ride in a car to Mumbai so that I can give a talk this afternoon. We left Pune about 6am and got here about 8.30 so the trip was a quite a bit quicker than coming here! I’ll post about that and include some pictures when I get a moment, but first I’ll post a quick announcement.

There will be an announcement on Monday 16th October at 10am EDT (3pm BST; 7.30pm in Pune) by `the National Science Foundation (NSF) as it brings together scientists from the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo collaborations, as well as representatives for some 70 observatories’. Further details can be found here. The European Southern Observatory has also announced that it will be holding a press conference on Monday about an `unprecedented discovery’.

The fact that it involves LIGO, Virgo and representatives of other observatories strongly suggests that this announcement will address the subject of the rumours that were flying around in August. In other words, it’s likely that on Monday we will hear about the first detecting of a coalescing binary neutron star system with an optical counterpart. Exciting times!

I’ll be back in Pune by Monday and will probably be able to watch the announcement and will update if and when I can.

Post-Planck Cosmology: Day 4

Posted in Talks and Reviews, The Universe and Stuff with tags , on October 12, 2017 by telescoper

So here we are at the end of the meeting, after a fourth and final day of wide-ranging cosmology talks. I did the first presentation at 9am. I won’t summarize my own lecture because you can find the slides here:

Here are two pictures of me in action:

me_2

me_1

After that we had, amongst others, invited talks by Subhabrata Majumdar on the eROSITA all-sky X-ray survey and Somak Raychaudhury (Director of IUCAA) on large-scale structures in the local universe, Kandu Subramanian on primordial magnetic fields and Anvar Shukurov on Probabilistic Topology and Morphology (a change to the advertised title). There were also a number of shorter talks of diverse nature mainly on the subject of large-scale structure and galaxy formation.

I have known Kandu Subramanian since I was a student at Sussex and he was a postdoc there. At that time he was working mainly on gravitational lensing. I haven’t seen him for quite a long time and was surprised to see that now his hair has gone completely white. That’s what happens to you if you work on primordial magnetic fields.

The afternoon session overran and I had an appointment for Skype call so I had to leave before the closing remarks, so let me take this opportunity to thank the conference organisers for putting together such an interesting meeting and especially for inviting me back to Pune after all this time. It has been very enjoyable.

Many of the conference guests have already left and some are leaving tomorrow. I am staying in India for a few more days, however. Tomorrow morning I’m going to Mumbai to give a talk at the Tata Institute for Fundamental Research. I have to get up early tomorrow for that trip so I think I’ll take an early night.

Post-Planck Cosmology: Day 3

Posted in The Universe and Stuff with tags , , , , on October 11, 2017 by telescoper

Before carrying on with my daily updates from this meeting on Post-Planck Cosmology I’ll just remark that this is a great venue: it has all the facilities necessary to keep a group of cosmologists happy…


At the tea break this morning I managed to find a shot that included all four of the statues in the main quadrangle too:

This morning kicked off with Roy Maartens discussing the cosmological potential of the Square Kilometre Array and other future galaxy surveys, one of his main points being the benefit of using multiple tracers to beat down some of the problems with single surveys.  The first phase of this project, SKA1,  will deliver 10 million redshifts with z<0.6. With SKA2 that will go up to 1 billion galaxies out to z<2, but many things can be done without redshifts using intensity mapping. SKA1 is some way off, but the precursor `Meerkat' consisting of 64 × 13.5 metre dishes will be hopefully starting next year in South Africa.

We then had a series of talks about reionization and the formation of the first stars, an epoch usually referred to as `Cosmic Dawn' or `First Light', taking us into lunch.

In the afternoon we had talks loosely grouped around the theme of `classical cosmology' – using geometric or other probes to study the expansion history of the Universe. This session included a talk by Chris Messenger of the LIGO collaboration about the beginnings of gravitational wave cosmology, though as the current generation of detectors is only sensitive to relatively nearby sources for the time being the main effort will be devoted to distance scale measurements, attempting to measure the Hubble constant directly without the need for the traditional distance ladder.

The last part of the day was devoted to a panel discussion, chaired by Francois Bouchet that was interesting and wide-ranging but largely motivated by responses to Paul Steinhardt's talk last night.

Now, no conference dinner to tear me away tonight – but I do have to finish my talk, which is at 9am tomorrow – so that will have to do for now. Toodle-pip!

Post-Planck Cosmology: Day 2

Posted in The Universe and Stuff with tags , , on October 10, 2017 by telescoper

Just finished the last session of the day and it’s only half an hour before the conference dinner begins, so I’ll just do a brief summary.

The weather in Pune continues to be `interesting’:

It’s pouring down at the moment, in fact. The session I chaired started late because we had to postpone the conference photograph because of inclement weather.

Anyway, this morning’s talks were primarily about the difficulties of measuring B-mode polarization in the cosmic microwave background. Carlo Baccigalupi gave a perspective on foregrounds from Planck and Zeeshan Ahmed updated us on Keck/BICEP progress. There are no new results from the latter – we’ll have to wait for data from the extra 220 GHz channel – but Zeeshan also spoke about a proposal for the next generation ground-based experiment, glamorously named CMB-S4 – details of which can be found here.

The afternoon was largely devoted to early universe physics, including inflation. We’re only two days in to the conference but already several speakers have showed this plot (from here), which shows the extent to which current cosmological data disfavours various inflationary models:

Some are disfavoured, but clearly there are still lots of viable models! Too many!

For the final session of the day we were joined by Paul Steinhardt via Skype from the USA. He gave a very cogent and stimulating talk arguing that the prevailing paradigm (i.e. inflation) was about to be overturned. I don’t have time to do a full summary of his contribution, but you can check out a previous post about some of the issues he raised, and here’s a picture of the last slide of his presentation:

Anyway, that will have to do. The conference dinner beckons.