Category Archives: science

links, science

We nearly missed …

As I said in my previous post, it’s been another busy week when I’ve just not had either the time or the mental energy for blogging, despite there being many things I wanted to write about. So in summary form here are a few that I picked up, would have liked to write more about, and which you may have missed. Let’s start with the the cute …

Berlin Zoo have some adorable new, but very rare, Rusty-Spotted Cat kittens. I defy anyone not to like these kittens.


Squirrels, L to R: Grey, Red, Melanistic (black) morph of Grey, Brunette morph of Red
While in Britain there’s another colour way of our favourite nut guzzler. But don’t be deceived the brunette squirrel is just a colour morph of our now rare red squirrel — just as there are black, grey squirrels.

Still on things biological the Evopropinquitous blog writes about Things I Learned as a Field Biologist. It’s often interesting and sometimes a bit squeamish. One wonders though how these people actually do any work in the field!

Now here’s something for real science geeks. Make your own Particle Detector from things you have around the house. No, I haven’t tried it (I have far too many left thumbs for craft work) but it certainly looks as if it should work.

From particle detectors, to particle generators. Except they weren’t. In interesting short post from IanVisits about the early plans for an underground railway in London which came to naught.


And finally this week for something different. Mr Bean-Blackadder has been throwing the toys out of his pram and probably annoying the righteous in the process. The Daily Telegraph reported a nice tirade from Rowan Atkinson: we must be allowed to insult each other. Joining in the campaign former shadow home secretary David Davis said:

The simple truth is that in a free society, there is no right not to be offended. For centuries, freedom of speech has been a vital part of British life.

Precisely. It’s called freedom of speech.

history, links, science

Missing …

Another selection of links to recent items you may have missed. This edition is an unusual mix of history and science.

Ben Goldacre, writer of the “Bad Science” column in the Guardian, has a new book out this week. Titled Bad Pharma it looks at the ways in which drug companies and their allies distort the evidence about the effectiveness of drugs and mislead regulators, doctors and patients. Here’s an extract.

Can I go back to bed now? We all suffer from insomnia at least occasionally. This Guardian item looks at the problem of persistent insomnia and current ideas on what to do about it.

It seems taking too many painkillers can give you a headache. Duh, my head hurts!

Humans eat humans. Well who knew? But now there is good evidence for prehistoric cannibalism which wasn’t just ritual.

I think we already knew that wild parrots name their babies, but here’s another look at the original study.

This interesting short item from the New York Times looks at the finding of a scrap of papyrus which appears to refer to Jesus’s wife.

Following up on a recent theme the Guardian (well they do have a good science stream) has a piece on the completion of the archaeological dig which may have found the remains of Richard III.

And finally after something like 60 years the experts have decided that three “fake” JMW Turner paintings are actually the genuine article. New technology has provided new evidence that has altered opinions. And finally it’s vindication for the collectors who bequeathed then the the National Museum of Wales.

personal, ramblings, science

On Hairiness

Now here is a mystery. Well at least it’s a mystery to me, and I can’t quickly find anything about it on the intertubes.

I’m one of those hairy males; I always have been. Fortunately I’m naturally mid-brown-ish of hair for if I were black haired I’d have to shave twice a day or spend more of my life looking like a villain.

As a child my hair was light brown; it got thicker and darker and wavy as I got to puberty. I ended up with something akin to a coconut mop on my head. Now I’m past three score years it is almost completely grey (the front is actually white), much finer, less wavy and thinning — though I’m nowhere near approaching going bald or even really receding.

But it isn’t head hair or beard that is my immediate interest, but body hair.

(No, no, I’m NOT going THERE!)

We know that as men get older their patterns of hairiness change. As I’ve said, head hair greys and gets thinner even to the extent of baldness; and apparently leg hair also decreases. Annoyingly though eyebrows, ears and noses sprout extraneous tufts of fur, which may also go grey.

(As an aside it’s also interesting that ears and noses continue to grow throughout life, with ears apparently growing at a rate of around a couple of millimetres every decade. Noses also appear to grow with age, hence the caricature of the old man with a large warty nose.)

But in the last few years I’ve noticed something else strange. I’m sure that the hair on my forearms and chest, maybe also my back, is getting longer as I get older. Not thicker, coarser or darker, but longer.

Now it does seem that men do go on growing body hair well past puberty, even into their 30s, and apparently most men over 35 are a lot hairier than they were in their 20s. But I’m talking about something I’ve only become aware of in the last few years, say from about age 55.

Now I can’t prove that my impression is right. I didn’t start measuring the length of my body hair at the age of 18 and don’t have a series of regular measurements throughout my life. (Just see what joys I’ve passed by!) Several searches using “a well known search engine” haven’t turned up any tufty hints.

Not, you understand, that I’m complaining. Inasmuch as I think about it at all I quite like being hairy; it’s part of me and it doesn’t bother me; I certainly wouldn’t shave or wax it. Ouchy!

Am I imagining things? Am I going mad? Do I have hairs on the palms of my hands? (No, not yet!) Does anyone know? If not, why not? — this is a vitally important research topic!

PS. No, no picture of my chest hair; you really didn’t want that much information, did you!?

ramblings, science

Fukushima Follow-up

The follow-up to the Fukushima accident, in the wake for the March 2011 earthquake and tsunami, continues.

In the last week there has been a thoughtful essay in the Wall Street Journal by physicist Richard Muller looking at the likely additional rates of cancer in Japan as a result of the nuclear problems.


What he says, and I have to assume his numbers are correct, is quite revealing. First a bit of background, which is in the article:

  • The average American gets an annual dose of 0.62 rem of radiation.
    (“A rem is the unit of measure used to gauge radiation damage to human tissue”.)
  • Anyone living in Denver gets 0.3 rem on top of that due to Radon gas from the local granite.
  • Yet Denver has a lower cancer rate the the US as a whole, despite its high radiation figures.
  • The International Commission on Radiological Protection recommends evacuating an area if the excess dose of radiation is just 0.1 rem. Yet people still live in Denver.
  • Following the accident the Fukushima evacuation zone showed radiation at the level of 0.1 rem.

So what does this mean? Well here is Muller’s explanation:

If you are exposed to a dose of 100 rem or more, you will get sick right away from radiation illness. You know what that’s like from people who have had radiation therapy: nausea, loss of hair, a general feeling of weakness. In the Fukushima accident, nobody got a dose this big; workers were restricted in their hours of exposure to try to make sure that none received a dose greater than 25 rem … At a larger dose — 250 to 350 rem — the symptoms become life-threatening … and your chance of dying (if untreated) is 50%.

Nevertheless, even a small number of rem can trigger an eventual cancer. A dose of 25 rem causes no radiation illness, but it gives you a 1% chance of getting cancer — in addition to the 20% chance you already have from “natural” causes. For larger doses, the danger is proportional to the dose, so a 50 rem dose gives you a 2% chance of getting cancer; 75 rem ups that to 3%. The cancer effects of these doses, from 25 to 75 rem, are well established by studies of the excess cancers caused by the atomic bombs at Hiroshima and Nagasaki in 1945 …

Here’s another way to calculate the danger of radiation: If 25 rem gives you a 1% chance of getting cancer, then a dose of 2,500 rem (25 rem times 100) implies that you will get cancer (a 100% chance). We can call this a cancer dose. A dose that high would kill you from radiation illness, but if spread out over 1,000 people, so that everyone received 2.5 rem on average, the 2,500 rem would still induce just one extra cancer … Rem measures radiation damage, and if there is one cancer’s worth of damage, it doesn’t matter how many people share that risk.

In short, if you want to know how many excess cancers there will be, multiply the population by the average dose per person and then divide by 2,500 (the cancer dose described above).

In Fukushima, the area exposed to the greatest radiation … had an estimated first-year dose of more than 2 rem. Some locations recorded doses as high as 22 rem …

How many cancers will such a dose trigger? … assume that the entire population of that 2-rem-plus region, about 22,000 people, received the highest dose: 22 rem. (This obviously overestimates the danger.) The number of excess cancers expected is the dose (22 rem) multiplied by the population (22,000), divided by 2,500. This equals 194 excess cancers.

Let’s compare that to the number of normal cancers in the same group. Even without the accident, the cancer rate is about 20% of the population, or 4,400 cancers. Can the additional 194 be detected? Yes, because many of them will be thyroid cancer, which is normally rare (but treatable). Other kinds of cancer will probably not be observable, because of the natural statistical variation of cancers.

Sadly, many of those 4,400 who die from “normal” cancer will die believing that their illness was caused by the nuclear reactor.

Sure these numbers are regrettable, and tragic for those affected. But by and large they will be indistinguishable from the variation in the normal background cancer rate, especially if the 194 excess cancers is (as Muller suggests) an over-estimate. It is the psychological effect on the people which is potentially the greater danger.

Let’s put this in a different context. One nuclear accident in 20 years is likely, over time, to result in somewhere around 200 deaths in Japan.

Compare that with coal mining where in China alone in 2004 there were over 6000 deaths of miners due to accident — plus any resulting from later pneumoconiosis. In fact it is estimated there are annually 4000 new cases pneumoconiosis just in the US. (Data from Wikipedia.)

Another comparison. We all take air travel for granted. Yet in the 12 years since 2000 plane crashes have caused on average 1183 death a year worldwide. (Data from the Air Crashes Record Office.)

(OK, a real comparison would cover far more data and causes, but you get the picture.)

Now there are other approaches to calculating the excess cancers caused. Another approach cited in Muller’s article suggests that Fukushima will cause 1500 excess cancers over a 70 year period. But I suggest that over such a long time period that number too is going to be pretty indistinguishable from the background. And anyway it is still a factor of at least 10 less than the number of people killed directly by the tsunami.

All of which leads Muller to conclude:

The reactor at Fukushima wasn’t designed to withstand a 9.0 earthquake or a 50-foot tsunami. Surrounding land was contaminated, and it will take years to recover. But it is remarkable how small the nuclear damage is compared with that of the earthquake and tsunami. The backup systems of the nuclear reactors … should be bolstered … We should always learn from tragedy. But should the Fukushima accident be used as a reason for putting an end to nuclear power?

Nothing can be made absolutely safe. Must we design nuclear reactors to withstand everything imaginable? What about an asteroid or comet impact? Or a nuclear war? No, of course not …

It is remarkable that so much attention has been given to the radioactive release from Fukushima, considering that the direct death and destruction from the tsunami was enormously greater. Perhaps the reason for the focus on the reactor meltdown is that it is a solvable problem; in contrast, there is no plausible way to protect Japan from 50-foot tsunamis …

Looking back more than a year after the event, it is clear that the Fukushima reactor complex, though nowhere close to state-of-the-art, was adequately designed to contain radiation. New reactors can be made even safer … but the bottom line is that Fukushima passed the test.

The great tragedy of the Fukushima accident is that Japan shut down all its nuclear reactors. Even though officials have now turned two back on, the hardships and economic disruptions induced by this policy will be enormous and will dwarf any danger from the reactors themselves.

Indeed. And hence I still believe — nuclear waste disposal problems not withstanding; I acknowledge that as an unsolved challenge — nuclear is our best and friendliest hope of managing our power requirements for the foreseeable future.

ramblings, science

A Special Day

Today is special. It is a red letter day. Well … no … actually it’s a blue moon! So anything could happen — allegedly.

The mostly used definition of a blue moon is where there are two full moons in a calendar month. But that it appears is a more modern definition, the older one being applied where there were four full moons in a season. Various older belief systems give each of the three normal full moons in a season a name. Where there are four full moons the third of the four is called a blue moon so that the last may keep it’s “correct” name and rightful place in the season.

Which might suggest to you that blue moons aren’t that rare. And you’d be right. They occur every 2-3 years (actually 7 times in the moon’s 19-year Metonic cycle), because of the mismatch between the 28 day lunar cycle and months of 30 or 31 days in our solar calendar.


Curiously it seems no-one really knows why it is called a blue moon, but it almost certainly isn’t because the moon suddenly becomes Smurf-coloured for the day. Smurf-coloured moons can happen but only as a result of significant atmospheric pollution, like the eruption of Krakatoa in 1883.

One theory for the name is that “blue” in this context is derived from the Old English word belewe meaning “betray” which was used to describe “false” moons entering the calendar. Well I suppose that’s possible, but given that the earliest known English reference dates from only 1524 it is perhaps unlikely.

Well, anyway, enjoy the last day of summer. In London it is bright and sunny but Autumnally cool, which is actually rather nice in what in the UK has been the wettest summer for 100 years. And if the sky is clear this evening go and bathe in the light of the blue moon! Sadly you’ll have to provide your own Blue Moon Cocktail.

You can find more on Blue Moons at:
Wikipedia : Blue Moon
Wikipedia : Full Moon Names
Wikipedia : Metonic Cycle
Jodrell Bank : Night Sky in August
And in various news stories, eg. here

links, science

What You May have Missed — Science Edition

Here’s a science-y edition of our occasional collections of links to articles you may have missed. They’re mostly not deep science, so they shouldn’t tax the brains of you arty types! In no particular order …

It can’t be so people can make pathetic jokes about their intelligence, so just why is it that so many women go blonde? Ah, of course, it’s all to make Miley Cyrus look so much sexier! 😉

An English major turned science writer is amongst those defending the teaching of algebra in school. It’s part of our cultural heritage.

Does your cat pester for food? If so it might need a psychologist. It would be beastly to deny the creature such a pleasure.

Oooo-eeerrr missus! Insect sting fetishes?! I don’t think so, thanks.

So is (human) virgin birth a reality? Despite lots of looking it seems the answer is still probably not. Some interesting stories though.

Here are two aspects, both from Scientific American, of some recent work on consciouslness. First of all the question of whether self-awareness requires a complex brain. And secondly, scientists are suggesting that octopi are conscious, by which they seem to mean they’re able to think.

And finally one for the medievalists out there … A guy called Rob Colautti has created an evolutionary history of dragons. Definitely gets my vote for cool link of the week!

ramblings, science, thoughts

On Atheism and Science

Yesterday I came across two blog posts about atheism, both of which deal with science in different ways. And they got me thinking — or at least starting to think — about the relationship between religion (or lack of it) and science.

Before I go into my thoughts let’s have a look at what, for me, were some of the salient points from the two articles, both of which are worth reading in their entirety.

The first is a post is Atheism Evolves by Maggie Mayhem (yes, the sex positive activist and sex educator):

[I]t’s ridiculous to believe that all life on earth exists to serve humans. I am appalled when I hear this by both the religious and the irreligious.
[…]
The bible does not teach me how my hand works. It doesn’t teach me about how the human hand came to be. It doesn’t teach me why a human hand is physically advantageous for certain tasks nor does it tell me anything about how a human hand was selected for over time.
[…]
Many preachers have been great philosophers, social revolutionaries, and leaders. However … activism and education does not have to include a literal belief in the supernatural to be effective and empowering.
[…]
There is no one to save us from ourselves but ourselves … No one has the divine right to exploit their fellow humans.
[…]
However, atheism and skepticism are movements that have been primarily driven by people with immense privilege because it has taken that much privilege not to be destroyed by others for saying something so counter to what we’ve been taught for as long as we’ve been humans.
[…]
A silly belief does not displace my own. Laws, exclusionary practices, and violent retaliation does displace people.
[…]
Tokenism only serves the privileged, it does not broaden the viewpoints and perspectives. It does not help us better understand ourselves and our world when white men get to decide which marginalized people get to speak. Nothing is accomplished with tokenism.
[…]
Ideas are not physical spaces: you cannot run out of room. One of the greatest things about them is the way they intermingle and breed and create unimaginable combinations.

(Emphasis in the original)

Before we go on, just think for a moment about those comments on privilege and on ideas.

… … …

Powerful aren’t they?!

OK, so now for the second article, Why Science Can’t Replace Religion by Keith Kloor on the scientific Discover Blogs.

[O]ur brains and bodies contain an awful lot of spiritual wiring … you can’t simply dismiss the psychological and cultural importance of religion. For much of our history, religion has deeply influenced all aspects of life, from how we cope with death and random disaster to what moral codes we abide by. That science should (or could) eliminate all this with a rationalist cleansing of civilization, as a vocal group of orthodox atheists have suggested, is highly improbable.
[…]
[S]ome people, no matter their background, are prone to experience a more spiritual, as opposed to rational, connection to the universe … certain needs unique to the human condition cannot be satisfied by science alone. Scientists who prefer a strictly rationalist lens have a hard time accepting this.
[…]
Absolutism is one of the uglier traits of religion that still pervades too many corners of the Earth today, breeding intolerance and normalizing abhorrent actions. But a response that indicts all religion as a stain on humanity is equally absolutist.

More rather powerful arguments, which strident atheists like Richard Dawkins and PZ Myers would do well to heed.

And it was reading this second article hot on the heels of the first which got me thinking. Actually thinking about this muddled interface between science and religion and the way the two so often seem to be unable to coexist.

What I realised was that there seem to be two strands to all religious belief, and these do seem to be to encompass all religions, not just Christianity. The two strands of belief are:
(a) how and why the world (universe) came into being, and
(b) the importance and imposition of a moral code.
Some believers seem to me to need to embrace one or other strand; some, although I surmise down at the deepest level a minority, clearly need both.

And it is in these two strands that the conflict with science arises because in fact these two strands have different roots, viz.
(a) has a root in science (of some form), whereas
(b) has its root in thought and intellect (philosophy, if you prefer).

Now I need religion for neither strand: science does indeed satisfy (to the extent satisfaction is possible by any means) the first and I have the intellect to be able to handle the latter myself.

The problem is that many people conflate and muddle the two strands and hence become completely, though unknowingly, confused. For science — whatever it’s underlying belief: creationist or evolutionist — cannot ipso facto produce morals; it is merely explanatory. And equally philosophy alone cannot produce technical explanations; observation and experiment (ie. science) are also required.

Consequently it is not unreasonable that some scientists need a spiritual dimension/belief to give them a moral/cultural grounding. Equally it is reasonable that (some) theologians and philosophers need science to help them make sense of the universe.

Lucky is the man who can derive both strands from a single belief system, whether that is a religion or science. OK, I happen to believe that the religious viewpoint is erroneous, but then I am lucky enough to be able to derive both strands without religion. Not everyone is so lucky, and perhaps we should be more sympathetic to that. Is it moral of us to deny a “crippled man” a crutch, whether physical or mental?

Now I’m conscious that this is likely not a fully enough developed train of thought, being as it was scribbled down in five minutes at 11pm last night. But the fact that there are these two, seemingly unrecognised, strands does (at least for me) explain some of the confusion about how some scientists can need religion (spirituality if you prefer) and how the religious/spiritual may need science.

Anyone want to expand on this?

amusements, science

A Rich Seam

The “Feedback” column in the latest edition of New Scientist (dated 4 August) mines a rich seam of amusements.

First there is an item reporting some mathematical work in pointless topology, which is what most of us thought about higher mathematics anyway.

There is an item reporting a conference call for papers as specifying All papers and presentations must be incomprehensible English, as would be expected at a technical conference.

And there’s a product description for a solar light which is ideal for areas where conversational electrical supply is not available.

This is followed by an amusing reference to the Large Hadron Kaleidoscope.

Finally I have to give you this piece in full as a masterpiece of lateral thinking:

Talk about units in Feedback reminds Tony Emerson of a story from “the 1950s or 60s” about “a scientist working in one of the atomic establishments”. This person got fed up with directives to use different systems of units — those based on the centimetre, gram and second; those semi-officially based on the metre, kilogram and second; and the very official units of the International Standards Organization. So they reported pressures in stones per acre.

The stone is a traditional English measure of the weight of people or grain — 14 pounds or 6.35 kg — and an acre, a unit of area, is 4047 square metres. As Tony says, stones per acre would be “the original agricultural unit” of crop yield. Its application to atomic research doesn’t bear thinking about.

Inspired!

natural history, science

Wasps

I know many people don’t like wasps. People are afraid of them because they buzz irritatingly and because we have learnt they sting — rather painfully. And yes they can be annoying little buzzers. Generally if you ignore them, they’ll ignore you; but if you annoy them they’ll order reinforcements (and yes they do — using pheromones!).

But I happen to think wasps are wonderful creatures, unless you are one of the unfortunate very few who are allergic to them (when they are actually rather dangerous).

In fact all the social insects (bees, wasps, ants, termites) are amazing for the way their colonies are run and organised. But I am especially fond of wasps, because without wasps we would not have life as we know it.

That sounds like an overstatement. And until the other day I might have agreed.


Vespula germanica, worker

First of all, what I already knew, is that wasps are incredibly useful predators. Without them we would be knee deep in creepy-crawlies. Our common European wasp species, Vespula vulgaris and V. germanica, predate caterpillars, and indeed other insect forms, which they feed to their grubs. Most of the other social wasps do this; and many of the solitary wasps parasitise caterpillars. In fact almost every pest insect species has at least one wasp species that preys upon it or parasitises it, making wasps critically important in natural control of pest numbers.

If you’re an insect, wasps are formidable predators with paralysing stings and razor sharp jaws. I’ve seen a common wasp catch a large bumblebee, sting/paralyse it, snip off it’s head, wings and legs and fly off with the body (which it could only just carry) — all in about 60 seconds.

Wasps will also take carrion to feed to their larvae. If you have wasps around, try leaving out small piece of red meat (raw or cooked) and if you’re lucky you can watch the wasps chopping off small chunks and taking them away. (By the way the adult wasps feed on nectar and sweet fruit which is why they become more of a nuisance in the Autumn when they look for more quick calories to keep them going.)

Wasps are also incredibly good at destroying dead wood. They use tiny slivers of wood, often chewed into paper, with which to build their nests. We have a handful of old pine logs in our garden and in a just 3 years or so the wasps have largely destroyed many of them. On a warm summer day you can watch a continual traffic of worker wasps cutting off slivers of wood and carrying them off.

All that I already knew. So now for what I didn’t know. Indeed what until recently no-one knew!

As if all the above wasn’t enough it turns out that yeasts, and especially Saccharomyces cerevisiae — that’s the common yeast we use for brewing beer, fermenting wine and proving bread — likely overwinter in the guts of hibernating queen wasps, ready to spread on the surface of fruit (especially grapes) the following summer. Yes, until very recently no one knew this, despite S. cerevisiae being scientifically very important as a “lab animal” as well as commercially (and socially!) valuable.

In a recently published piece of research (you can find fuller reports here and here) scientists worked out that many species and strains of yeasts were overwintering inside queen wasps, being transmitted in the Spring to their new larvae, which then as adults reinfected fruits. Wash; rinse; repeat.

Other mechanisms for yeast overwintering are proposed, so this may not be the only way. But it looks as if it may well be a very important way. And it is a route which was totally unknown until recently. (In fact the natural history of yeasts is generally poorly understood, despite their importance.) As always more research, and more questions, beckon.

This is why I love science. We are still making amazing discoveries like this. The more we look, the curiouser and curiouser the natural world is.

Moral: If you have wasps around, LEAVE THEM ALONE; they’re amazing little creatures which provide us some good service.

amusements, ramblings, science

Why I am a Chemist

There was an interesting article by Ashutosh Jogalekar on Scientific American Blogs yesterday called Why I am a chemist.

Ash makes many good points, but especially that chemistry underlies all the biology and physics and engineering that we see about us. Without chemistry (the design, synthesis and understanding of materials) we would have none of that: nothing from the early smelting of iron and bronze, through the Romans’ skills with glass, right through to modern concrete and carbon fibre.

Yes, chemistry encompasses everything from the synthesis of smelly bubbling green liquids, through the power of detergents, to a deep understanding of molecular structure via spectroscopy (which is what I did) and quantum mechanics.

All of this is chemistry. And it all underpins our world, both artificial and natural. Without chemistry we wouldn’t have modern anti-cancer drugs, or modern anaesthetics; we wouldn’t understand the biochemistry underlying photosynthesis; we wouldn’t have air-bags in cars or rockets that can take us to the Moon and beyond.

That is why I trained as a chemist. I wanted to understand how these things worked. (Although I probably couldn’t have put it is so many words at the time.)

And I am still sad that I had to give it all up because the mid-1970s recession meant there were no sensible jobs for chemists. That’s what happens in a recession, we lose the skills we’ve invested in, because no-one can afford to invest for the future. I can understand why, and it is a fine line to walk, but it is short-sighted especially when the education system is so unattractive as a job option that those who are displaced are lost to the discipline and not even attracted to teach and enthuse a future generation.

Would I do things differently if I had my time over again? Probably yes, if I knew then what I know now. I would certainly have worked harder (not difficult) to stay in research. And I might have looked more favourably on teaching. I certainly would have liked to continue as a working scientist rather than “selling out” (as my father saw it) to commerce. Science is much more fun that selling things.

Could I go back to it? No, not now, after nearly 40 years out of the field — much as I might like to. But at least I have retained a broad interest in science, and not just chemistry, so with luck I can still enthuse a few others along their path.

And it is still the simple things in science that enthral me. How metals are smelted. Why snowflakes have six-fold symmetry. How compounds are light sensitive. How detergents work.