Archive for the The Universe and Stuff Category

Predictive Blogging

Posted in Covid-19, Cricket, Opera, Politics, The Universe and Stuff with tags , on May 27, 2020 by telescoper

News has emerged that on 14th April 2020 Dominic Cummings doctored an old blog post to make it look like he had predicted a coronavirus outbreak. Given the indisputable fact that Mr Cummings is a career liar this should not in itself come as a surprise. What might surprise a few people is that this episode reveals that this self-styled genius is must in reality be rather stupid if he thought he could get away with hiding such a blatant attempt at self-promotion. Still, the truth obviously no longer matters in post-Brexit Britain so he probably won’t face any serious consequences.

I, of course would, never add things to old blog posts to make myself look clever.

I would, however, like to point out just a few of the various uncannily accurate predictions I have made in the course of my almost twelve years of blogging.

For example, in this September 2009 review of a performance of La Traviata by Welsh National Opera I wrote:

My love of Italian opera makes me regret even more that the UK will be be leaving the European Union in 2020.

And in this account of the May 2015 England versus New Zealand Test Match at Lord’s you will find:

… it was still quite gloomy and dark. My mood was sombre, thinking about Donald Trump’s forthcoming victory in the 2016 United States Presidential Elections.

My prescience is not only limited to politics, however. In my 2013 post about the Queen’s Birthday Honours List you will read:

The name that stood out for me in this year’s list is Professor Jim Hough, who gets an OBE. Jim is Professor of Experimental Physics at the University of Glasgow, and his speciality is in the detection of gravitational waves. Gravitational waves haven’t actually been detected yet, of course, but the experimental techniques designed to find them have increased their sensitivity by many orders of magnitude in recent years, Jim having played a large part in those improvements. I imagine he will be absolutely thrilled in February 2016, when gravitational waves are finally detected.

You see now that Niels Bohr wasn’t quite right when he said “It is difficult to make predictions, especially about the future”. Sometimes it’s the past that’s hardest to predict.

 

Cosmology Talks – Deanna Hooper on CMB spectral distortions

Posted in The Universe and Stuff with tags , , , , on May 26, 2020 by telescoper

Here is another one of those Cosmology Talks curated on YouTube by Shaun Hotchkiss. This one was published over a month ago, but I missed it at the time.

In the talk, Deanna Hooper tells us about what we could learn from future measurements of the spectral distortions in the CMB, as well as how spectral distortions complement current and future measurements of CMB anisotropies. I’m particularly interested in this as I wrote a paper on it with John Barrow almost thirty years 30 ago and it’s fascinating to see how far the field has moved on from the theoretical point of view. Our paper was motivated by limits on spectral distortions imposed by the FIRAS instrument on COBE, and there hasn’t been anywhere near as much observational progress since then.

The paper that accompanies this talk can be found here.

Watch “Why the Universe is quite disappointing really – Episode 5” on YouTube

Posted in The Universe and Stuff, YouTube with tags , , , on May 21, 2020 by telescoper

Episode 5, in which I explain using a golf ball just how empty the Universe is. It is so empty, in fact, that even the crowded places are very empty. And as for the empty places, they’re practically nothing.

Watch “Why the Universe is quite disappointing, really – Episode 4” on YouTube

Posted in The Universe and Stuff, YouTube with tags , , , , on May 19, 2020 by telescoper

Episode 4, in which I show that spiral galaxies are very grubby – they contain huge amounts of dust. And not only galaxies – astronomical dust is everywhere we look. The Universe may be big, but it sure is dirty..

Hubble Tension in Perspective

Posted in The Universe and Stuff with tags , , , on May 18, 2020 by telescoper

In my office today for the first time in a couple of months I stumbled across a folder containing the notes from the summer school for new Astronomy PhD students I attended in Durham in 1985. Yes, that’s thirty five years ago..

Among the lectures was a set given by Richard Ellis on Observational Cosmology from which I’ve taken this little snippet about the Hubble Constant:

It’s not only a trip down memory lane but also up the cosmological distance ladder! You will see that there were two main estimates, one low and one high. Both turned out to be about three sigma away from the currently-favoured value of around 70.

Plus ça change, plus c’est la même chose…

Does this change your mind about today’s tension between another pair of “low” (67) and “high” (73) values?

The Geostationary Orbit

Posted in Cute Problems, The Universe and Stuff with tags , , , on May 16, 2020 by telescoper

I’m was mucking out this blog’s blocked comments folder and unsurprisingly found a few from Mr Hine, a regular if sadly deranged correspondent.

One of his blocked comments begins

In the forlorn hope that Mr Hine might some day learn something scientifically correct I thought I’d repost this problem, which is very easy if you have a high school education in physics or applied mathematics but no doubt very difficult if you’re Mr Hine.

Verify that the radius of a circular geostationary orbit around the Earth is about 42,000 km, i.e. find the radius of a circular orbit around the Earth which has a period of 24 hours so that its orbital period matches the Earth’s rotation period, thus ensuring that an object travelling in such an orbit in the same direction as the Earth’s rotation is always above the same point on the Earth’s surface.

(You will need to look up the mass of the Earth.)

Cosmology Talks: Adam Riess on Cepheid Crowding and the Hubble Tension

Posted in The Universe and Stuff with tags , , , , , on May 15, 2020 by telescoper

Here’s another example from the series of cosmology talks being curated by Shaun Hotchkiss. In this one, esteemed astronomer and Nobel Prize winner Adam Riess talks about what he and collaborators considered to be the leading candidate for a systematic error in the SHOES measurement of the expansion rate of the Universe. This is “Cepheid crowding”, the possibility that background sources change our interpretation of Cepheid brightness, ruining one step in the SHOES distance ladder. Riess and collaborators devise a nice way to test whether the crowding is correctly accounted for and find that it is, so crowding cannot be the “explanation” of an error in the distance ladder measurement of H0. Riess also stresses that both the early and late universe measurements of H0 are now backed up by multiple different measurements. Accordingly, if the resolution isn’t fundamental physics, then no single systematic can entirely solve the tension.

P. S. The paper that accompanies this talk can be found on the arXiv here.

How to Solve Physics Problems

Posted in Cute Problems, Education, Maynooth, The Universe and Stuff, YouTube with tags , , on May 14, 2020 by telescoper

Since the examination period here at Maynooth University begins tomorrow I thought I would use the opportunity provided by my brand new YouTube channel to present a video version of a post I did a few years ago about how to solve Physics problems. These are intended for the type of problems students might encounter at high school or undergraduate level either in examinations or in homework. I’ve tried to keep the advice as general as possible though so hopefully students in other fields might find this useful too.

Watch “Why the Universe is quite disappointing, really – Episode 3” on YouTube

Posted in The Universe and Stuff, YouTube on May 12, 2020 by telescoper

Why the Universe is quite disappointing really – Episode 3, in which I give two examples of biological systems that are inefficient and poorly designed. If these are the product of intelligent design, the designer clearly wasn’t concentrating.

Watch “Why the Universe is quite disappointing really – Episode 2” on YouTube

Posted in The Universe and Stuff, YouTube with tags , , on May 8, 2020 by telescoper

Episode 2, in which I explain how stars limp along unimpressively, making very poor use of the resources available to them, not doing a very good job at what they’re supposed to be doing, and then they die.

Just like people really…