Tuesday, April 21, 2015

"Quirky Quantum Concepts" by Eric L. Michelsen



You've taken a first course in quantum mechanics. You know your way round Schrödinger’s equation, eigenstates and eigenvalues, and you've thoroughly explored the hydrogen atom. But deep down you’re confused.

You read about Schrödinger’s Cat and that you don’t see superpositions ‘in real life’ because of ‘decoherence’, but what’s that? Populist accounts talk airily about the’ leakage of phase information into the environment’, but that sort of hand-waving hardly adds clarity. The technical literature discusses the exponential decay of off-diagonal terms in the density matrix ... but what’s physically going on?

You read about the various interpretations. Is the wave function part of reality? Is it just a subjective statement of the experimenter’s state of knowledge? So much ink discussing the significance of Schrödinger’s equation: and of course, that eponymous equation isn't even correct. The road to the truth about quantum mechanics must run through its relativistic cousin, quantum field theory. But what a chasm separates you, the student, from this towering intellectual achievement. No-one can explain in accessible terms what QFT is all about,  the map of the territory. Saying baldly that ‘at each point in space and time there are an infinite number of simple harmonic oscillators (with creation and annihilation operators) for each type of fundamental particle‘  ... doesn’t do it for most people.

What you need is a book in which these concepts are discussed via simple models, mathematically clear but at a level accessible to people who've completed a first course in quantum mechanics at undergraduate level (and understood it). Eric Michelsen has admirably succeeded in this book, which is a natural successor to Gary Bowman’s Essential Quantum Mechanics. In both cases the texts are meant to be read alongside a traditional textbook, but focus on conceptual clarity – what is the maths really saying? – and a careful linkage with what’s observed in reality.

Quirky Quantum Concepts covers many other topics.  There are fine reviews of wave mechanics itself; scattering (barely touched on in most elementary classes); matrix mechanics and density matrices; angular momentum; and the QM treatment of multi-electron atoms. But for me the clear treatment of loss of coherence and the very introductory but rigorous and comprehensible guide to QED/QFT were the high points of this excellent book.

(Note: as a bonus, the PDF is available on the Internet. I bought the book not just through guilt – it’s easier to flip to and fro in hard copy).

Monday, April 20, 2015

The Birds

Some pix from before this blog got started in 2005, chosen for their avian amusement index, mostly.

This is Birdworld in Surrey


The Hawk Conservancy Trust, Andover


Flamingos at Birldworld

Tomorrow we may go for a picnic at Ebbor Gorge where, no doubt, a giant Roc will swoop down and carry us away ... .

Dubito ergo sum


I have this on the wall in my study.

Sunday, April 19, 2015

The Amazing Hibernating Cat

Scene: Sunday afternoon. Clare is reading the Saga magazine of summer holiday cruises, focusing on a pleasantly indolent two weeks on the Greek islands.

"Fourteen days with plenty of time to ourselves; it's one out of three on their 'hectic' meter. I'm beginning to think that Saga knows me."

"You mean, like IKEA and Waitrose 'know' you?"

"Of course, we couldn't do it until the cat goes."

Note: although the cat can theoretically live for an indefinite period in our absence, subsisting on a mound of dry cat food, in practice it tends to panic and go neurotic if left more than three days by itself. Plus occasional dribbling and vomiting, decaying vole corpses, the odd bird ...

"You're possibly not aware that the animal is a creature of many surprising talents. I was planning on dropping him into one of the freezer compartments. Then he'd be no bother at all."

A glare.



"In fact it's a shame we don't have a microwave, as a gentle defrost would be just the thing to bring him round, once we're back."

"You spend too much time with your mother's robot pets."

---

How's that hedgehog gene-splicing thing going? I'm in!

Saturday, April 18, 2015

Alien Galactic Engineering in The Economist this week

Interesting piece in The Economist this week.
"A spacefaring civilisation, even one relying on craft travelling at far below the speed of light, would be able to colonise the entire galaxy in a few hundred million years. It therefore follows that if intelligent, technologically capable life forms had emerged elsewhere in the Milky Way, they would probably have done so long enough ago that they would, by now, be everywhere — which evidently they are not. This line of reasoning suggests humans really are the only intelligent life in this particular galaxy.

"Perhaps, therefore, the search for aliens is looking in the wrong place. The calculation that intelligent life will rapidly colonise its entire home galaxy — first made by Michael Hart, an American astrophysicist, in 1975 — suggests it is not other solar systems which should be scoured for little green men, but other galaxies. And this is just what Roger Griffith, an astronomer at Pennsylvania State University, has done."


...

"Dr Griffith reasoned that a galaxy inhabited by Dyson-sphere-constructing aliens would have an unusual, infrared-rich and visible-light-poor spectrum. With the aid of an American space telescope called the Wide-field Infrared Survey Explorer, he searched 100,000 galaxies for such spectra. What he found, as he reports in the Astrophysical Journal, is tantalising.

"No galaxies appeared to host civilisations that were using more than 85% of the available starlight as a power source. Fifty, however, were red enough to be hosting aliens gobbling up half or more of their starlight. Since even the most enthusiastic colonists would not, presumably, set up shop around every single star, and also because realistic versions of Dyson spheres would not totally enclose a star, these galaxies might indeed be the empires of individual alien species.

"Power-hungry aliens are not, sadly, the only explanation for the spectra Dr Griffith has found. More prosaic things, such as vast clouds of interstellar dust, might produce a similar signal. Nevertheless, these 50 unusual galaxies (and also 95 more which had spectra that were weird in other ways) might repay further study. The odds are that Dr Griffith’s discovery will have a humdrum explanation. But it is just possible he has answered the age-old question of whether humanity is alone."
Dr Griffith has checked out a large number of galaxies, but there are at least one hundred billion in the observable universe so he's sampling at a ratio of one in a million. If there are aliens with super-powers anywhere in the universe, this approach - scaled up - seems an effective way of getting the evidence in.

---

Look at this from the viewpoint of physics, not biology - or 'life-sentimentalism'. What we call life (or more properly, biological ecology) is an exponential process of environmental self-reconstruction. Inorganic-stuff turning itself into ever more life-stuff. A chemical self-organising diffusion process powered by free energy.

Ignore all the fine-grained details of 'intelligence', 'technology' and endogenous 'lofty aspirations'. From a sufficient number of millions of light years away, the galactic spread of free-energy-exploiting alien life is indistinguishable from the runaway infestation/transformation of a sterile, pristine galaxy by 'grey goo'.

---

There are people who rather like galaxies as they are now. Should we call them misozoic (after this and this)? You read it here first.

Thursday, April 16, 2015

Genius

Outside the conference room my manager congratulated me. As usual, I had sat quietly through the first part of the meeting, absorbing the atmosphere and soaking up the arguments. The client had come, as usual, mob-handed and opinionated: their technical team had been sold on a centralised solution by our competition – sweetened with easy payment terms. Our own kit was smaller, more distributed and our presentation was not going well.

I asked a few questions, probing their likely go-to-market strategy; the rate of uptake of their product-set in today’s challenging economic conditions. As usual, I saw that people began to pay attention to what I was saying; it usually takes about ten minutes. Carefully I outlined the CAPEX profile of our offer – its greater flexibility and enhanced alignment with their future revenue streams. I could see they were taking it on board.

As our customers were led out of the sleek boardroom through plush front offices, I exited into the warren of dingy corridors and flickering fluorescents which bore witness to our own struggle for margins. The coffee machine was next to Anna’s desk at the entrance to a cluttered, open-plan office. Anna was a manager in HR, mid-thirties and quite tall with a short blonde bob – I found her rather attractive. She was talking to some female underling, a dumpy woman with long, mousy-brown hair. Anna caught my eye as I came in but turned away. I heard her quietly confiding to her companion, “We’ve been having meetings about him,” indicating me with a small nod of her head.

The mousy one gave me a side-long glance as Anna continued to whisper to her, “Some of the stuff he’s written. It was quite a lot of trouble clearing up after him.”

I felt I was not really meant to be overhearing these remarks so I ignored them. The coffee was now ready – I prevent scalding by always using one plastic cup inside another – and I walked past Anna, quite struck in a way by her appearance.

“Anna, you’re looking really great today,” I said with a smile. My remark was measured and honest and I was sure she would be pleased to hear it. I swept from the room, followed by her impassive gaze.

Next day I was sufficiently concerned to obliquely raise the topic with my boss. He was a solid kind of person, about ten years older than me, and although he in no way sparkled, he seemed to fit well into the management hierarchy. At least he kept all the logistics out of my hair. Sometimes I wanted to go to some of his meetings – I was sure I could sort out the endless confusions and stupidities he was prone occasionally to remark upon – but to my minor irritation I never seemed to get invited. “You need to spend your time on the important stuff,” I was told, “Leave the routine meetings to me, that’s what I get paid for.” Somewhat mollified, I would return to my online manuals, research papers and computer models.

So I broached the subject with him when I next passed him in the corridor.

“HR seems to be having meetings to discuss ‘my case’. Any idea what that’s all about?”

I had intended the question to be ironic or droll but his eyes slid obliquely past me and for some reason he seemed a trifle uncomfortable.

 “Well, you know HR. They’re paid to calm people down. I expect those rather lengthy emails you sent recently explaining the weaknesses of our current product line might have caused a stir. Some of the senior executives aren't exactly used to direct contact from the technical staff, and some of them are a bit conservative.”

I was prepared to be stroppy about this news - idiots! - but since my manager seemed to share my views ... . And besides, he was still talking.

“And of course we value your customer-centeredness; the customer is at the centre of everything we do. I’m sure we get added value and future credibility when you frankly point out to them some of the weaknesses in our current product set. Still, you can see that some of the sales execs might get a bit over-excited.”

“What do they know,” I snorted derisively.

“Yes, well. And no-one has ever formally complained about your dress-sense in front of clients – obviously you don’t look like a salesman, but your suit sort of fits, the shirtsleeves aren't unacceptably short, and no-one is going to be looking at your ankles anyway.”

I checked my current apparel. Today I was relaxed, just doing my normal job, no outsiders to worry about. I was wearing a faded pair of denim trousers, comfortable if a little washed-out; yellow suede desert boots (which I also used when working in the garden at home - there were residual cement stains); a checked shirt - rather worn around the neck; and a green coarse-wool pullover with shrunken sleeves which, as usual I had rolled up. It was the outfit I used to think with.  I sniffed:  hmm, perhaps I should have showered this morning.

I gazed back at my manager with a degree of annoyance. Wasn't he paid to keep those annoying bureaucrats and managers off my back?
___

Ⓒ Nigel Seel, April 2015. 

I'm currently preoccupied with the concept of "biting the hand that feeds you" - something I see everywhere at the moment. So amusing where it occurs. I'll leave it to others to gauge how much of the story above is autobiographical.

Previous story: Phytocide.

Wednesday, April 15, 2015

Maunsel Lock (TA7 0DH)

Nice day today so we took a picnic to Maunsel Lock, on the Bridgwater-Taunton canal. If the tsunami ever comes, the Somerset Levels will be scrubbed clear, so admire this charming Somerset construct while you can!

Maunsel Lock

The author at his favourite haunt: the Maunsel Tea Shop

Notice the pillbox machine-gun emplacement on the right; me neither ...

Jupiter
At Maunsel Lock you are in the centre of the famous Somerset Space Walk, (so famous I had not heard of it until today). The sun is located (scaled down a little) near the tea shop; the planets are marked canal-side at their appropriate distances and to scale. One pace equates to about 400,000 km (Pluto is 11 km away).

Ambling along at three miles an hour (8 paces in five seconds) I calculated we were walking at just over twice the speed of light. Light is real slow, you know, for getting around the solar system.

---

Trivia: I'm re-reading Alastair Reynolds' Chasm City. I'd forgotten how intricate and cleverly constructed this novel is. While slow to get started, it's gradually becoming somewhat addictive.

Monday, April 13, 2015

Clare's paintings

During our sojourn in the States back in 2001/2, Clare had a fair amount of time on her hands while I was participating in Cable & Wireless Global's stately descent into terrain (Chapter 11 in 2004). She took up painting and here is her gallery from that time.

"Flames"

"Freesias"

"Planes over Wolftrap"

"The Matrix"

"Steel Tooth"

"Wolftrap Theater in the Woods"

A Cable & Wireless colleague once asked to buy "Freesias". She said she had always liked the "Primitive" style. I smiled demurely and declined her offer; I never had the nerve to tell Clare.

Sunday, April 12, 2015

The World's Top Fifty Experiences (yawn!)


Another glossy magazine pops through our door, listing the world's top fifty experiences (and sponsored by Fred Olsen cruises). Typical delights:
  • Afternoon tea at Raffles, Singapore
  • Dance with a local tribe in Kenya
  • Climb Sydney Harbour Bridge
  • Discover the awe-inspiring Taj Mahal
  • Learn flamenco in Seville
... and so on for another forty five achingly-familiar tourist jaunts which feature on everybody's bucket list (except for me, apparently).

Here are my top five experiences.

1. Discovering how to solve an equation like x2 = 5x - 6. Look, x occurs on both sides but no adding or subtracting can get x on one side and a pure number on the other. The revelatory secret is to factorise the equation as (x-3)(x-2) = 0 and realise that of all the possible values for x, only two can make this equation true.

2. Getting calculus. The magic of moving effortlessly between distance, velocity and acceleration; the solving of maxima and minima problems; the secret to working out mysterious stuff like the area of a circle and the volume of a cone from first principles.

3. Finally understanding the phrase "the collapse of the wave function" and then realising the deeper mystery as to how in the world this could happen (if it does).

4. Realising that the structure of our universe is not determined by lengths as we measure them with a ruler (Euclidean distance) but by the strange pseudo-metric of special relativity.  We really live in Minkowski space-time which is very different from the illusion of space we see around us, but I can't visualise it, even in lower-dimensional analogues. Frustrating.

5. Comprehending the architecture of intelligent agents like chess-playing machines or autonomous robots - how to design machine systems which really can solve problems in the world (this is not obvious).

So these are my top life-enhancing experiences, none of which involve crowded airport queues, cramped aircraft seats and losing your luggage.

Friday, April 10, 2015

Classic pix: Skyline Drive and the Blue Ridge Mountains

A couple of days ago I was reminiscing about our brief residence in the States back in 2001/2002. Having shown you pictures from Miami, New York and San Francisco I thought I would add some from our trip to Skyline Drive in the Blue Ridge Mountains of Virginia, in November 2001.

Clare on Skyline Drive

The Blue Ridge Mountains

This is how I thought Virginians dressed at that time ...
Clare was recovering from a hip replacement operation at this time - Skyline was much-needed therapy.

Thursday, April 09, 2015

A struggle to launch

Quick trip down to Clarks Village, Street this morning to get Clare some summer cycling pants.

The puma is go ...

A category 4, but almost a 'failure to launch' ...

I went to the gym instead; no-one ever face-planted, took a case of 'road rash' or broke their collar bone on an exercise bike.