Writer’s Block

Posted in Biographical, Books, Talks and Reviews on August 31, 2014 by telescoper

A few people have asked why I’ve had the sheer effrontery to take a week off and come to Cardiff. Well, it may surprise you to learn that even Heads of School have a holiday entitlement, and in the 18 months I’ve been in that position I’ve only managed to take a small fraction of mine!

But the real reason for this break is that I need some time without disturbance to finish off the long-awaited Second Edition of Cosmology: A Very Short Introduction. Dorothy made me a subtle sign for my office door, but it has proved largely ineffective at preventing distractions. So here I am, back in the Cardiff residence, blocking out as much as I can to get on with some writing.

I hope this clarifies the situation.

Cold War Cardiff

Posted in Uncategorized with tags , on August 30, 2014 by telescoper

Here I am, back in Cardiff. Though given the roadblocks metal fences and hordes of armed police, you might be forgiven for thinking it was Berlin at the height of the Cold War.

All of beautiful Bute Park is fenced off, and there’s considerable disruption to the traffic through the city. All this will last over a month, and the NATO boondoggle isn’t even here. It actually takes place near Newport, twenty miles away. They’re just using Cardiff for two days..

Whoever made the decision to force this nonsense on the City should be held to account. There should be a full public inquiry into the gross abuse of power. And I hope the people of Cardiff remember this, and express their outrage at the Council when they vote at the next elections..

The photo, by the way, is at the bridge over the Taff at Cowbridge Road. Or is it Checkpoint Charlie?

NATO Cardiff: is this what democracy looks like?

Posted in Politics with tags , , , , on August 29, 2014 by telescoper

telescoper:

I’m off to Cardiff this evening, and hope at some point over the weekend to take some pictures of the monstrous barrier described in this post by Keith Flett that has been put up all around town. One of the most important points about this month-long fiasco is that there was no consultation whatsoever with the people of Cardiff before the decision was taken to waste such a vast amount of money. No doubt that’s because if there had been a consultation the response would have been overwhelmingly negative. Who will be held to account? My guess is “nobody”…

Originally posted on Kmflett's Blog:

Nato Cardiff: is this what democracy looks like?
I live in North London and central Cardiff something that seems to surprise some of my social media followers but is explained by the nature of my job as a union officer and the fact that my partner happens to live in Cardiff…

Next week on 4/5th September there is a Nato Summit meeting, not in Cardiff but at the Celtic Manor hotel outside Newport on the M4.

I’m no fan of Nato. It contains the word ‘treaty’ in its name and history suggests that treaties are an excellent way of starting wars. In addition it appears to be run largely by people who have more than a passing similarity to Dr Strangelove. Of course its opponents are mostly unlovely as well.

Anyway if you are going to have a Nato summit and lots of, at the least, self styled statesmen [&…

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Pallas’s Cat

Posted in Uncategorized with tags , on August 29, 2014 by telescoper

Too busy for a proper post today as I’ve got a lot to do before going off for a spot of annual leave. I’m therefore resorting to a standard ploy in such situation, posting a video of a cat. The short clip below features no ordinary cat, however. It’s an example of Pallas’s Cat, Otocolobus manul, a wonderful – but sadly endangered – creature which lives wild in the steppes of Central Asia. Here’s a fine specimen captured in a still photograph:

Pallas_Cat

Although it appears very stocky because of its long fur, it’s actually no bigger than an average domestic cat.

The clip is a valuable reminder to us all that even the coolest and most dignified animals on Earth  can be hilarious when placed in an unfamiliar situation. This one has clearly just spotted a camera outside its lair….

 

Round the Horn Antenna

Posted in LGBT, The Universe and Stuff with tags , , , , , on August 28, 2014 by telescoper

The other day I was looking through my copy of Monthly Notices of the Royal Astronomical Society (which I buy for the dirty pictures).  Turning my attention to the personal columns, I discovered an advertisement for the Science & Technology Facilities Council which is, apparently, considering investing in new space missions related to astronomy and cosmology. Always eager to push back the frontiers of science, I hurried down to their address in Swindon to find out what was going on.

 

ME: (Knocks on door) Hello. Is there anyone there?

JULIAN: Oh hello! My name’s Julian, and this is my friend Sandy.

SANDY: Oooh hello! What can we do for you?

ME: Hello to you both. Is this Polaris House?

JULIAN: Not quite. Since we took over we changed the name…

ME: To?

SANDY: It’s now called Polari House…

JULIAN: ..on account of that’s the only language spoken around here.

ME: So you’re in charge of the British Space Programme then?

JULIAN:  Yes, owing to the budget, the national handbag isn’t as full as it used to be so now it’s just me and her.

SANDY: But never fear we’re both dab hands with thrusters.

JULIAN: Our motto is “You can vada about in any band, with a satellite run  by Jules and…

SANDY: …Sand.

ME: I heard that you’re looking for some input.

SANDY: Ooooh. He’s bold, in’e?

ME: I mean for your consultation exercise…

JULIAN: Oh yes. I forgot about that. Well I’m sure we’d welcome your contribution any time, ducky.

ME: Well I was wondering what you could tell me about Moonlite?

SANDY: You’ve come to the right place. She had an experience by Moonlight, didn’t you Jules?

JULIAN: Yes. Up the Acropolis…

ME: I mean the Space Mission “Moonlite”

SANDY: Oh, of course. Well, it’s only small but it’s very stimulating.

JULIAN: Hmmm.

SANDY: Yes. It gets blasted off into space and whooshes off to the Moon…

JULIAN: …the backside thereof…

SANDY: ..and when it gets there it shoves these probes in to see what happens.

ME: Why?

SANDY: Why not?

ME: Seems a bit pointless to me.

JULIAN: There’s no pleasing some people is there?

ME: Haven’t you got anything more impressive?

SANDY: Like what?

ME:  Maybe something that goes a bit further out? Mars, perhaps?

JULIAN: Well the French have this plan to send some great butch omi to troll around on Mars but we haven’t got the metzas so we have to satisfy ourselves with something a bit more bijou…

SANDY: Hmm…You can say that again.

JULIAN: You don’t have to be big to be bona.

SANDY: Anyway, we had our shot at Mars and it went willets up.

ME: Oh yes, I remember that thing named after a dog.

JULIAN: That’s right. Poodle.

ME: Do you think a man will ever get as far as Uranus?

JULIAN&SANDY: Oooh! Bold!

SANDY: Well I’ll tell you what. I’ll show you something that can vada out to the very edge of the Universe!

ME: That sounds exciting.

JULIAN: I’ll try to get it up right now.

ME: Well…er…

JULIAN: I mean on the computer

ME: I say, that’s an impressive piece of equipment

JULIAN: Thank you

SANDY: Oh don’t encourage her…

ME: I meant the computer.

JULIAN: Yes, it’s a 14″ console.

SANDY:  And, believe me, 14 inches will console anyone!

JULIAN; There you are. Look at that.

ME: It looks very impressive. What is it?

SANDY: This is an experiment designed to charper for the heat of the Big Bang.

JULIAN. Ooer.

SANDY: The Americans launched WMAP and the Europeans had PLANCK. We’ve merged the two ideas and have called it ….PLMAP.

ME: Wouldn’t it have been better if you’d made the name the other way around? I mean with the first bit of WMAP and the second bit of Planck. On second thoughts maybe not..

JULIAN: It’s a little down-market but we have high hopes.

SANDY: Yes, Planck had two instruments called HFI and LFI. We couldn’t afford two so we made do with one.

JULIAN: It’s called MFI. That’s why it’s a bit naff.

ME: I see. What are these two round things either side?

SANDY: They’re the bolometers…

ME: What is this this long thing in between pointing up? And why is it leaning to one side?

SANDY: Well that’s not unusual in my experience …

JULIAN:  Shush. It’s an off-axis Gregorian telescope if you must know.

ME: And what about this round the back?

SANDY: That’s your actual dish. It’s very receptive, if you know what I mean.

ME: What’s that inside?

JULIAN: That’s a horn antenna. We didn’t make that ourselves. We had to get it from elsewhere.

ME: So who gave you the horn?

SANDY: That’s for us to know and you to find out!

ME: So what does it all do?

JULIAN: It’s designed to make a map of what George Smoot called “The Eek of God”.

ME: Can it do polarization?

JULIAN: But of course! We polari-ize everything!

ME: Like BICEP?

JULIAN: Cheeky!

SANDY: Of course. We’re partial to a nice lally too!

JULIAN: But seriously, it’s fabulosa…

SANDY: …Or it would be if someone hadn’t neglected to read the small print.

ME: Why? Is there a problem?

JULIAN: Well, frankly, yes. We ran out of money.

SANDY: It was only when we got it out the box we realised.

ME: What?

JULIAN & SANDY: Batteries Not Included!

With apologies to Barry Took and Marty Feldman, who wrote the original Julian and Sandy sketches performed by Hugh Paddick (Julian) and Kenneth Williams (Sandy) for the radio show Round the Horne. Here’s an example of the real thing:

 

 

 

 

 

 

Stokes V – The Lost Parameter

Posted in The Universe and Stuff with tags , , , , , , on August 27, 2014 by telescoper

Some years ago I went to a seminar on the design of an experiment to measure the polarization of the cosmic microwave background. At the end of the talk I asked what seemed to me to be an innocent question. The point of my question was the speaker had focussed entirely on measuring the intensity of the radiation (I) and the two Stokes Parameters that measure linear polarization of the radiation (usually called Q and U). How difficult, I asked, would it be to measure the remaining Stokes parameter V (which quantifies circular polarization)?

There was a sharp intake of breath among the audience and the speaker responded with a curt “the cosmic microwave background is not circularly polarized”. It is true that in the standard cosmological theory the microwave background is produced by Thomson scattering in the early Universe which produces partial linear polarization, so that Q and U are non-zero, but not circular polarization so V=0. However, I had really asked my question because I had an idea that it might be worth measuring V (or at least putting an upper limit on it) in order to assess the level of instrumental systematics (which are a serious issue with polarization measurements).

I was reminded of this episode when I saw a paper on the arXiv today by Asantha Cooray, Alessandro Melchiorri and Joe Silk which points out that the CMB may well have some level of circular polarization. When light travels through a region containing plasma and a magnetic field, circular polarization can be generated from linear polarization via a process called Faraday conversion. For this to happen, the polarization vector of the incident radiation (defined by the direction of its E-field) must have non-zero component along the local magnetic field, i.e. the B-field. Charged particles are free to move only along B, so the component of E parallel to B is absorbed and re-emitted by these charges, thus leading to phase difference between it and the component of E orthogonal to B and hence to the circular polarization. This is related to the perhaps more familiar process of Faraday rotation, which causes the plane of linear polarization to rotate when polarized radiation travels through a region containing a magnetic field.

Anyway, here is the abstract of the paper

The primordial anisotropies of the cosmic microwave background (CMB) are linearly polarized via Compton-scattering. The Faraday conversion process during the propagation of polarized CMB photons through regions of the large-scale structure containing magnetized relativistic plasma, such as galaxy clusters, will lead to a circularly polarized contribution. Though the resulting Stokes-V parameter is of order 10-9 at frequencies of 10 GHz, the contribution can potentially reach the total Stokes-U at low frequencies due to the cubic dependence on the wavelength. In future, the detection of circular polarization of CMB can be used as a potential probe of the physical properties associated with relativistic particle populations in large-scale structures.

It’s an interesting idea, but it’s hard for me to judge the feasibility of measuring a value of Stokes V as low as 10-9. Clearly it would only work at frequencies much lower than those probed by current CMB experiments such as BICEP2 (which operates at 150 GHz). Perhaps if the speaker had answered my question all those years ago I’d be in a better position to decide!

After Bank Holiday

Posted in Poetry with tags , , on August 26, 2014 by telescoper

Now deserted are the roads
Where awhile the lovers went;
Vacant are the field-abodes
Where a vivid hour they spent:
Solemn dark
Broods again in lane and park.

‘Tis no matter where are gone
Those warm lives—to halls, maybe,
Festive, or to lodgings lone:
Of the land their tenancy
Now is o’er;
Earth to earth belongs once more.

Gone are they as hourly goes
From the sombre fields of space
Our world, with its little glows—
Passion’s ship that has no place,
Leaves no track,
On time’s endless ocean black.

by Elizabeth Daryush (1887-1977)

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