Archive for January, 2014

Inflation and the Multiverse

Posted in Astrohype, The Universe and Stuff with tags , , , , , , on January 6, 2014 by telescoper

I was quite excited when I discovered, via Twitter, a paper on the arXiv with the title Quantum Fluctuations in Cosmology and How They Lead to a Multiverse, which was written by one of the architects of the inflationary universe scenario, Alan Guth. Despite numerous attempts to understand the argument how inflation leads to a Multiverse I’ve never really succeeded. To me it always seemed like  a version of the Mind Projection Fallacy inspired by a frequentist interpretation of probability: the construction of notional ensembles for the purposes of calculation in quantum mechanics does not imply that such ensembles are realized in nature. In fact I’ve never found much more substance in articles about this issue than the assertion that Quantum Physics = Woo! = Multiverse.

Anyway, since the paper I found is a review article I hoped it would help teach me the error of my ways. Here is the abstract

This article discusses density perturbations in inflationary models, offering a pedagogical description of how these perturbations are generated by quantum fluctuations in the early universe. A key feature of inflation is that that rapid expansion can stretch microscopic fluctuations to cosmological proportions. I discuss also another important conseqence of quantum fluctuations: the fact that almost all inflationary models become eternal, so that once inflation starts, it never stops.

My eye was drawn to the phrase “almost all inflationary models”.  I had hoped to see “almost all” used in its strict mathematical sense, ie “apart from a set of measure zero” with the measure being fully specified. Disappointingly, it isn’t.   Guth discusses the consequences of the tail  the inflationary potential V (for large values of the inflaton field ϕ) on the long-term evolution of inflationary dynamics and then states

Since V3/2/|V ′| grows without bound as ϕ → ∞ for most potentials under consideration, almost all models allow for eternal inflation.

This means, to me, most models people have constructed but doesn’t mean all possible models. I don’t doubt that some inflationary models  become eternal, but would have preferred a more rigorous statement.  This is particularly strange because Guth spends the last section of his paper discussing the “measure problem”:

While the multiverse picture looks very plausible in the context of inflationary cosmology — at least to me — it raises a thorny and unsolved problem, known as the “measure problem.” Specifically, we do not know how to define probabilities in the multiverse.

The measure problem to my mind also extends to the space of all possible inflationary theories.

And then there’s the title, which, I remind you, is Quantum Fluctuations in Cosmology and How They Lead to a Multiverse. Guth’s argument consists of going through the (standard) calculation of the spectrum of cosmological density fluctuations (which does fit a host of observational data). He then states:

Since the density perturbation calculations have been incredibly successful, it seems to make sense to take seriously the assumptions behind these calculations, and follow them where they lead. I have to admit that there is no clear consensus among cosmologists, but to many of us the assumptions seem to be pointing to eternal inflation, and the multiverse.

I have to admit that I get a bit annoyed when I read a paper in which the actual conclusions are much weaker than implied by the title, but that seems to be par for the course in this field.

For the record, I’ll state that I am an agnostic about the multiverse. It may be a correct idea, it may not. I will say, however, that I still haven’t found any article that puts it on a firm scientific footing. That may well, of course, just be a measure of my ignorance. If you know of one, please let me know through the comments box.

Ashes Whitewash Woe

Posted in Cricket with tags , , on January 5, 2014 by telescoper

I’m hoping that writing a blog post about the Ashes tour might provide some kind of catharsis, so here goes.

England lost the fifth and final Ashes test today by 281 runs and so have lost all five tests. It’s not that long ago that they suffered a similar fate on tour in Australia (2007, in fact) but I think this series has been a lot worse. None of the matches have been close-fought, as the following summary proves:

21-25 Nov: First Test, Brisbane: Australia won by 381 runs

5-9 Dec: 2nd Test, Adelaide: Australia won by 218 runs

13-17 Dec: 3rd Test, Perth: Australia won by 150 runs

26-30 Dec: 4th Test, Melbourne: Australia won by eight wickets

3-7 Jan 2014: 5th Test, Sydney: Australia won by 281 runs

The final Test summed up the series. England briefly promised with the ball, having Australia in trouble at 97-5, but were unable to push home their advantage as the hosts recovered to 326. England’s batsmen then capitulated for a paltry 155 having been in danger (at 23-5) of being all out for their lowest-ever Ashes total of 45. The Australians amassed another 276 in only 61 overs and then watched England crumble again in pitiful fashion, for 166 in only 32 overs. Hopeless by England, but well played Australia.

So what has gone wrong? The obvious answer is England’s batting; they’ve scored under 200 in six innings in the series, and only one England batsman (Stokes) managed a century. Credit to the Australian bowlers, of course – Mitchell Johnson’s total of 37 wickets at an average of under 14 was truly outstanding – but good bowling can’t be the only factor. Experienced batsmen like Cook, Bell and Pietersen have all been found wanting. I know they had to hostile and determined fast bowling, but this is Test cricket. Top players have to stand up and be counted. The failures of less experienced players such as Carberry and Root are more forgivable, given the poor example set by senior batsmen, but I think they’re also symptomatic of something drastically wrong with the coaching system employed by the England team management. Good batsmen don’t spontaneously turn into bad ones.

The England bowling hasn’t been much to write home about either, with only Stuart Broad turning in a respectable statistic of 21 wickets at 27.52. Jimmy Anderson is a dangerous bowler when the ball swings, but that hasn’t happened for him on this tour and he only managed 14 wickets at an average of 43.92. Swann’s bowling average was a woeful 80 before he threw in the towel.

England coach Andy Flower has stated that this is the End of An Era for English cricket. I hope the powers that be have the courage and vision to take the steps needed to pull English cricket out of its calamitous downward spiral. That means rethinking the entire coaching set-up rather than just tinkering with the team selection.

It will, however, be interesting to see which survivors of this debacle will play Test cricket this summer. Trott and Swann are already out of contention. I’d be surprised if Cook remains as skipper, though he might keep his place as an opener if he shows form in county matches. Carberry does not look like a top class opener to me, and Root is no world class number 3 either. Let’s hope Bell can recover some form and provide some stability while the selectors look to blood new players. I think Pietersen should stay too, exasperating though he is.

The only ray of sunshine I can find is in the performance of young Ben Stokes, who topped the England batting averages with 34.87 and took 15 wickets at 32.80. It’s early days for him, as he is only 22, but has England at last found the genuine all-rounder that it has missed for so long?

A Perihelion Poser

Posted in Cute Problems, The Universe and Stuff with tags , , , on January 4, 2014 by telescoper

Today (January 4th) the Earth is at perihelion, ie its closest approach to the Sun. This may surprise folk in the Northern hemisphere who think that winter and summer are determined the Earth’s distance from the Sun…

Anyway, here’s an easy little question. The eccentricity of the Earth’s orbit is 0.017. Estimate the percentage difference in the flux of energy arriving at Earth from the Sun at the extremes of its orbit (ie at perihelion and aphelion). Is this difference likely to have any significant effect?

Answers through the comment box please..

40 years since the beginning of the ‘three day week’

Posted in History, Politics with tags , , , on January 4, 2014 by telescoper

Is it really 40 Years ago?
I wonder how many of you are old enough to remember the “Three Day Week”? I am. In fact I remember sitting my 11+ examination right in the middle of the period (from January to March 1974) in which electricity supplies across the UK were restricted to three days per week. Although it meant reading books by candlelight, it wasn’t as bad as it may sound to younger readers because we didn’t have that many electrical gadgets in those days and at least our house was heated by coal, not electricity. I dread to think what would happen nowadays if we should experience  problems with fuel supplied similar to those caused by the Oil Crisis of 1974. But such an event is not altogether impossible…

hatfulofhistory's avatarNew Historical Express

 

This week marks the 40th anniversary of the beginning of the ‘three day week’, which lasted from 1 January to 6 March 1974. The ‘three day week’ was an initiative by the Heath Government to avoid the stand-still of Britain’s industry in response to the Oil Crisis of late 1973 and the threat of a strike by the National Union of Mineworkers (who were on a ‘work to rule’ basis at the time). It involved cutting electricity supplies to three consecutive days per week to conserve coal stocks, which was threatened by a strike by mineworkers.

A search of the digitised Cabinet Papers available through the National Archives show how the Heath Government approached the looming threat of a strike by the NUM and the energy crisis faced by Britain in 1973-74. One Cabinet meeting from 20 December, 1973 outlined the problem facing the Heath Government and the…

View original post 1,175 more words

Book Review: Cosmology: A Very Short Introduction by Peter Coles

Posted in Books, Talks and Reviews with tags , on January 4, 2014 by telescoper

Here’s a review of my book “Cosmology: A Very Short Introduction” that I found a couple of days ago. I’m reposting as an excuse to remind folk that a new edition will be out later this year, or as soon as I’ve finished writing it, because my proposal has been formally approved by Oxford University Press.

Sipech's avatarThe Alethiophile

It is rare for me to walk into a bookshop and walk out again without buying at least one book; more often than not, it’s two or three at a time. This was one I picked up in the summer when I went to visit the royal observatory and national maritime museum in Greenwich, as there was an exhibition on at the latter which was on the subject of cosmology. There were various options open, though I chose not to get the enormous hardback book full of images from the Hubble space telescope.

For those of you who are unaware, I studied maths at university, with a particular emphasis on mathematical physics. In my first year, I took a free elective module in cosmology. So while I do review this book as an expert in the field, I do review it as an informed and educated amateur.

Of all branches…

View original post 1,172 more words

Lines on the Death of Phil Everly

Posted in Uncategorized on January 4, 2014 by telescoper

So farewell, then,
Phil Everly.

You were one
Half
Of the
Righteous
Brothers.

Or was that
Someone else?

Anyway, now 
All you have
To do is
Dream
Dream
Dream
For ever
And
Everly.

by Peter Coles (aged 50½).

A Long Day’s Journey into Brighton

Posted in Biographical on January 3, 2014 by telescoper

Just time for a quick post before I have my Ovaltine. I travelled back to Brighton today by train from Cardiff, where I’d spent a few days either side of New Year.

The journey back to Brighton was a bit of a struggle, courtesy of heavy overnight rain and a later, more mysterious, problem with “lightning damaging equipment” – which must be an impressive piece of kit! Anyway, trains could only move at a crawl between Cardiff and Newport while a temporary signalling system was in place, ie a man standing on a ladder waving a flag. I think he’s still there as I write this.

An hour after leaving Cardiff the train made it to Newport (a distance of about 15 miles) and then gave up. We all got out and waited another half an hour for a train to London Paddington.

After that it all went reasonably well, and I got to London Victoria a mere four and a half hours after leaving my Cardiff residence. I was relieved to see a Brighton train due to leave at 19.36 which I got on, but since it was only four carriages long it was packed. I managed to find a seat in the section marked “Priority” which, naturally, applies to me.

Anyway I got back to the flat about 9pm, so the journey was six hours door-to-door. Not too bad, really, given the inclement weather, though I can’t help wondering why our railway network is so terribly vulnerable to the effects of rain? It’s not exactly a rare occurrence in Britain, is it?

Could we not divert just a small fraction of the money spent on glitzy new stations towards better flood protection and/or more robust signalling equipment?

Anyway, back to work tomorrow – much to do before next week when I’ll be travelling again, a tad further this time..

In Place of Fear

Posted in Politics with tags , , on January 2, 2014 by telescoper

An extract from the fifth chapter, In Place of Fear, of Nye Bevan’s book of essays, published in 1952, has been circulating on the internet. I’m taking the liberty of posting it here because it addresses directly (and more cogently than modern politicians seem to be able to manage) the importance of the “civilising principle” behind the National Health Service – that nobody should be denied medical assistance because they can’t afford it. As Bevan himself puts it:

Society becomes more wholesome, more serene, and spiritually healthier, if it knows that its citizens have at the back of their consciousness the knowledge that not only themselves, but all their fellows, have access, when ill, to the best that medical skill can provide. But private charity and endowment, although inescapably essential at one time, cannot meet the cost of all this. If the job is to be done, the state must accept financial responsibility.

Part of this essay could have been written in 2013 rather than 1952, in response to government proposals that “foreigners” or “migrants” (or, as I prefer to call them, “people”) should be denied treatment on the NHS unless they can prove their entitlement. Bevan deals with this suggestion very well, but I think there is a point that he missed. Even if you accept that foreign visitors should be denied access to the NHS on grounds that they don’t contribute by taxation (which of course they do as soon as they buy anything that attracts VAT or earn wages in the UK), then logically you should also ban the unemployed, students, etc from access to free health care. I like to think that as a nation we wouldn’t countenance this, so why do pick out foreign visitors in this way? The answer is, of course, pure xenophobia – the lowest common denominator of British politics now as it was then..

Here is the nub of Bevan’s argument about visitors:

One of the consequences of the universality of the British Health Service is the free treatment of foreign visitors. This has given rise to a great deal of criticism, most of it ill-informed and some of it deliberately mischievous. Why should people come to Britain and enjoy the benefits of the free Health Service when they do not subscribe to the national revenues? So the argument goes. No doubt a little of this objection is still based on the confusion about contributions to which I have referred. The fact is, of course, that visitors to Britain subscribe to the national revenues as soon as they start consuming certain commodities, drink and tobacco for example, and entertainment. They make no direct contribution to the cost of the Health Service any more than does a British citizen.

However, there are a number of more potent reasons why it would be unwise as well as mean to withhold the free service from the visitor to Britain. How do we distinguish a visitor from anybody else? Are British citizens to carry means of identification everywhere to prove that they are not visitors? For if the sheep are to be separated from the goats both must be classified. What began as an attempt to keep the Health Service for ourselves would end by being a nuisance to everybody. Happily, this is one of those occasions when generosity and convenience march together. The cost of looking after the visitor who falls ill cannot amount to more than a negligible fraction of £399,000,000, the total cost of the Health Service. It is not difficult to arrive at an approximate estimate. All we have to do is look up the number of visitors to Great Britain during one year and assume they would make the same use of the Health Service as a similar number of Britishers. Divide the total cost of the Service by the population and you get the answer. I had the estimate taken out and it amounted to about £200,000 a year. Obviously this is an overestimate because people who go for holidays are not likely to need a doctor’s attention as much as others. However, there it is. for what it is worth and you will see it does not justify the fuss that has been made about it.

The whole agitation has a nasty taste. Instead of rejoicing at the opportunity to practice a civilized principle, Conservatives have tried to exploit the most disreputable emotions in this among many other attempts to discredit socialized medicine.

The numbers quoted above are very interesting. The current NHS budget for England is just a shade under £100 billion (c.f. £400 million in the 50s). The estimated current cost to the NHS of treating visitors is (possibly) as high £500 million, ie around 0.5% of the total budget. That’s a larger proportion (by about a factor 10) than in the 50s, presumably because international travel is far easier nowadays, but since migrant workers contribute a net £25 billion to the UK economy it’s hardly excessive. Indeed, the NHS itself could not function at all without the thousands of doctors and nurses who come from other countries to work in it. Neither would our university system, as a matter of fact.

It’s about time some of our politicians had the guts to stand up against the growing tide of foreigner-bashing. The one problem this country has with immigration is that there isn’t enough of it.

Anyway, my New Year message to any potential visitors to these shores, whether they be Bulgarians or Romanians or any other citizens of this planet, is a great big Welcome. And if you get ill while you’re here we’ll look after you. Because we’re like that. At least, I hope we are.

An Astronomical Teaser

Posted in Cute Problems, The Universe and Stuff with tags , , , , on January 1, 2014 by telescoper

For those of you who feel up to a little brain-teaser after last night’s revels, try this little problem which involves the use of everybody’s favourite type of astronomical measurement, the magnitude system. Answers through the comment box please!

A binary star at a distance of 100 pc has such a small separation between its component stars that it is unresolved by a telescope. If the apparent visual magnitude of the combined image of the system is 10.5, and one star is known to have an absolute visual magnitude of 9.0, what is the absolute visual magnitude of the other star?

To make an end is to make a beginning

Posted in Poetry with tags , , , on January 1, 2014 by telescoper

So, it’s New Year’s Day again. I’d like to take the opportunity to convey my very best wishes to everyone who follows this blog and to thank you all for showing an interest in my ramblings.

The beginning of a new year seems an appropriate time to post something from T.S. Eliot’s remarkable poetic meditation on the redemptive nature of time, Four Quartets. This is the last section, Part V, of the last of the four poems, Little Gidding.

What we call the beginning is often the end
And to make and end is to make a beginning.
The end is where we start from. And every phrase
And sentence that is right (where every word is at home,
Taking its place to support the others,
The word neither diffident nor ostentatious,
An easy commerce of the old and the new,
The common word exact without vulgarity,
The formal word precise but not pedantic,
The complete consort dancing together)
Every phrase and every sentence is an end and a beginning,
Every poem an epitaph. And any action
Is a step to the block, to the fire, down the sea’s throat
Or to an illegible stone: and that is where we start.
We die with the dying:
See, they depart, and we go with them.
We are born with the dead:
See, they return, and bring us with them.
The moment of the rose and the moment of the yew-tree
Are of equal duration. A people without history
Is not redeemed from time, for history is a pattern
Of timeless moments. So, while the light fails
On a winter’s afternoon, in a secluded chapel
History is now and England.

With the drawing of this Love and the voice of this
     Calling

We shall not cease from exploration
And the end of all our exploring
Will be to arrive where we started
And know the place for the first time.
Through the unknown, unremembered gate
When the last of earth left to discover
Is that which was the beginning;
At the source of the longest river
The voice of the hidden waterfall
And the children in the apple-tree
Not known, because not looked for
But heard, half-heard, in the stillness
Between two waves of the sea.
Quick now, here, now, always—
A condition of complete simplicity
(Costing not less than everything)
And all shall be well and
All manner of thing shall be well
When the tongues of flame are in-folded
Into the crowned knot of fire
And the fire and the rose are one.

Little Gidding, Part V, the last of the Four Quartets by T.S. Eliot.