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The Cosmic Web in Maynooth

Posted in Books, Talks and Reviews, Talks and Reviews, The Universe and Stuff with tags , , on November 5, 2019 by telescoper

Next week (10th to 17th November) in Ireland is Science Week and this will be celebrated by a number of events here in Maynooth, among which is a talk by yours truly on 15th November:

Here is a short description:

How can we map the distribution of galaxies over thousands of millions of light years? What does the Universe look like on these scales? How did get to look like that? And how do we know?This talk will explain how astronomers and cosmologists have come together over the past couple of decades to make huge surveys of the Universe, revealing the existence of a complex but beautiful `Cosmic Web’ with vast chains of galaxies strung out around immense dark voids. These observational breakthroughs have been mirrored by advances in theory and computer simulation that allow us to understand how this amazing structure was born 14 billion years ago in the Big Bang and has been growing and evolving ever since. Free and open to TY, 5th and 6th year students, this talk will be of particular interest in those interested astronomy, space, physics and the Universe itself!

It is on in the morning to make it possible for school students to attend and the talk is adapted to this audience, so it won’t be the same as the one I gave in Dublin last week. The timing seems to have worked because the lecture theatre has over 200 seats in it but is already almost full. There are still a few places available so if you’re in the area you can book here.

 

 

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First Light at the Dark Energy Spectroscopic Instrument

Posted in The Universe and Stuff with tags , , , , , , on November 4, 2019 by telescoper

While I was away last week there was quite a lot of press coverage (e.g. here) about the new Dark Energy Spectroscopic Instrument, which has just seen first light. I didn’t have time to mention this until now, and in any case  I have little to add to the coverage that has already appeared, but it does give me the excuse to post this nice video – which features quite a few people I actually know! – to describe  the huge galaxy survey that DESI will perform. It’s hard to believe that when I started in the field in 1985 the largest such survey, which took several years to compile, had only a few thousand galaxies in it. The DESI instrument will be able to determine spectra of more sources than that in a single pointing of the telescope that lasts about 20 minutes. Overall it should determine redshifts of over 35 million galaxies! Vorsprung durch Technik.

 

 

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The Cosmic Web at DIAS

Posted in Books, Talks and Reviews, The Universe and Stuff with tags , , on November 1, 2019 by telescoper

Yesterday evening found me at the Dublin Institute for Advanced Studies, complete with scary Hallowe’en beard, to give a talk.

Picture Credit: Prof. Luke Drury

It was a nice friendly audience and we had a lot of interesting discussions afterwards. As usual on such occasions I’ve put up the slides in case anyone wants to see them:

After the talk I headed back to Maynooth. It was a very rainy night, but at least some of the fireworks were going off despite the potential for damp squibs.

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The Royal Society really needs to work on its history of the telescope

Posted in History, The Universe and Stuff with tags , , , on October 30, 2019 by telescoper

An important corrective to frequently repeated fallacies about the history of telescopes in astronomy. The Royal Society really shouldn’t be making mistakes like this!

thonyc's avatarThe Renaissance Mathematicus

One would think that the Royal Society being one of the eldest, but not the eldest as they like to claim, scientific societies in Europe when presenting themselves as purveyors of the history of science, would take the trouble to get their facts right. If, however, one thought this, one would be wrong. Last week on the Internet the Royal Society was pushing a slide show, under their own name, on Google Arts and Culture on the history of the telescope in astronomy that in terms of historical accuracy is less than one, as a historian of science, nay of the telescope, might hope or indeed wish for.

The slide show in question is titled, Silent Harmony: astronomy at the Royal Society: Discover how innovation in telescopes and other optical instruments changed the way we see the universe. Following the title slide we have another general blurb slide…

View original post 835 more words

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The Gaia video!

Posted in The Universe and Stuff with tags , on October 24, 2019 by telescoper

I’ve blogged quite a few times about the European Space Agency’s Gaia mission (see this tag). Social media brought this nice new video to my attention this morning so I couldn’t resist adding it to the collection. I don’t think it accompanies any new data release or scientific results but it’s very impressive anyway!

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Most Popular Programming Languages 1965-2019

Posted in The Universe and Stuff with tags , , , on October 21, 2019 by telescoper

I find this absolutely fascinating. I’ve programmed in Fortran, Pascal, Basic, Assembler, C, C++, Javascript and Python lived long enough to see quite the fashion for most of these languages come and go on a relatively short timescale. Perhaps it provides a salutary lesson for those who think their current Python codes will always be useful?

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Gravitational Lensing, Cosmological Distances and the Hubble Constant

Posted in The Universe and Stuff with tags , , , on October 17, 2019 by telescoper

To continue the ongoing Hubble constant theme, there is an interesting paper on the arXiv by Shajib et al. about determining a distance to a gravitational lens system; I grabbed the above pretty picture from the paper.

The abstract is:

 

You can click on this to make it bigger. You will see that this approach gives a `high’ value of H0 ≈ 74.2, consistent with local stellar distances measures, rather than with the `cosmological’ value which comes in around H0 ≈ 67 or so. It’s also consistent with the value derived from other gravitational lens studies discussed here.

Here’s my ongoing poll on the Hubble constant, with

 

 

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More Hubble Constant Tension

Posted in The Universe and Stuff with tags , , , on October 14, 2019 by telescoper

Here’s the abstract of another contribution to ongoing discussions around so-called tension between different estimates of the Hubble Constantpolldaddy (see this blog passim):

You can find the actual paper (by Lin, Mack and Hou) on the arXiv here.

Now, before Mr Hine starts to fill up my blocked comments folder with rants, I will add a few comments of my own.

First, at the Royal Astronomical Society on Friday I discussed all this with a renowned observational astronomer and expert on stellar distance measurements. He agreed with me that if the `tension’ is indeed real then it is far more likely to be a problem with stellar distance measurements than the cosmology.

Second, I am writing a review of all this to be published in Astronomy & Geophysics next year. Watch this space.

Third, this gives me an excuse to include yet again my poll on whether you are worried about the “tension”:

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Peebles Princeton Press Conference

Posted in The Universe and Stuff with tags , , on October 10, 2019 by telescoper

Here I am in the Departure Lounge of Dublin Airport’s Terminal 2 ready for a quick trip to Poundland. To fill in a few minutes before my flight I thought I’d post this video of the press conference held at Princeton University upon the announcement of the award of a Nobel Prize to Jim Peebles. It’s full of interesting things but I particularly liked this quote:

My advice is not to aim for prizes and awards. They will come or they won’t. Don’t judge your career by their number, by the count of prizes. We’re in this for the joy of research, the fascination, the love of science. That is the reward really…

Don’t judge yourself by the awards. Judge yourself by how well you have done, and do your best.

For me that sums up the whole reason for being a physicist. Even those of us who have no chance of winning awards or prizes and whose achievements are at most modest can still feel the joy and the love of science. That is the reward.

 

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A Nobel Prize for Jim Peebles!

Posted in The Universe and Stuff with tags , , , , , , on October 8, 2019 by telescoper

I’ve just dashed back in excitement to the office from two hours of mandatory Financial Report Training to write a quick post before my 12 o’clock lecture on Astrophysics & Cosmology because of the news about the award of the 2019 Nobel Prize for Physics.

My recent post was half right in the sense that half this year’s prize goes to Michel Mayor and Didier Queloz for the discovery of an extrasolar planet. I don’t know either of them personally, but heartiest congratulations to both!

My heart lept with joy, however, to see the other half of the prize go to Jim Peebles (above) for his work on theoretical cosmology. Much of the reason for that is that I’ve had the great honour and pleasure to meet Jim many times over the years. He is not only a truly great scientist but also a extremely nice man whose kindness and generosity is universally recognized. He’s not known as `Gentleman Jim’ for nothing!

The other reason for the excitement is that I was completely taken by surprise by the announcement. I had feared that his chance of winning a Nobel Prize had passed – I argued at the time that Jim should have been awarded a share of the 2006 Nobel Prize because without his amazing pioneering theoretical work the importance of the cosmic microwave background for cosmology and the large-scale structure of the Universe would not have been established so rapidly. As an author of the first paper to provide a theoretical interpretation of the signal detected by Penzias and Wilson, Jim was there right at the start of the modern era of cosmology and his subsequent work constructed the foundations of the theory of structure formation through gravitational instability. I was sad that he didn’t get a share in 2006 for this work, but am absolutely delighted that this has been rectified now!

This was one of the first cosmology books I ever bought. It’s an amazing piece of work that has been essential reading for cosmologists for almost 40 years!

Congratulations to Jim!

Now let me think about what to say to my students about this!

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