Elephant in the hole
Did the elephant plunge into the black hole, or just spiral around it (28 October, p 36)? Your example makes a significant and troubling departure from how I had previously understood the event horizon paradox.
Poor Dumbo is said to be in two places “at the same time”. If Susskind et al. are really claiming that the internal observer (Bob, poor chap) sees Dumbo plunge through “while” Alice sees the elephant still spiralling toward the event horizon, what stops us extending the thought experiment?
To Alice, Dumbo hasn’t actually crossed the horizon, so with one mighty flap of his ears he could still escape the black hole and return safely to whichever Mickey Mouse bunch of scientists had sent him there in the first place. And if Dumbo were feeling particularly perverse he could try the same trick again, skimming the black hole just long enough for Bob to see him plunge in, again and again, adding mass to the black hole 鈥� but mass which Alice would not detect.
In the process he would also break the “Xerox principle” quoted in the article. Unless some quantum-gravitational magic is invoked to produce a (prohibited) copy of Dumbo, surely the same core issue applies in your article’s thought experiment? If Alice sees Dumbo reduced to ash by Hawking radiation near the event horizon, then Dumbo never made it through and Bob cannot see him in the black hole (though I suspect that would actually be the least of his problems).
From Dieter Gold
The theory is certainly interesting, but I do not think it is physics 鈥� yet. Physics explains nature and has to withstand experimental results. What distinguishes physics from philosophy is trying everything possible to falsify the theory. This means first showing that the new theory is congruent with experimental facts, and then to predict yet unknown results.
I suppose it is easier to imagine a holographic counterpart of a world than to draft experiments whose results can be compared with the theory. Thought experiments acceptable for physicists and not literary zoologists would be a first step.
Voiron, France
From John Ulrich
Now just one minute. It is claimed that an elephant can be in two places at once because an observer accelerating outside an event horizon sees the elephant outside the event horizon at the same time as another observer riding the free-falling elephant is inside the horizon. But a fundamental principle of relativity holds that the phrase “at the same time” has no meaning unless both observers occupy the same inertial reference frame. This is certainly not true of the thought experiment described.
Whidbey Island, Washington, US
The editor writes:
Yes, but the observers can agree on how to convert between their times so that while one sees the elephant outside, the other must be inside. Incidentally this does not violate the conservation of energy either, because although it is in two places, there is still only one elephant.
Old water wisdom
You suggest that recharging groundwater by controlled leakage from surface water reservoirs is a radical new way of thinking (23 September, p 4). People in developing countries have been doing this for hundreds, if not thousands of years. Now the news has finally reached me in Malawi, I applaud its adoption in Kansas.
It may be novel there, but in many parts of India each village has a small reservoir (generally known as a “tank”) that impounds monsoon run-off and slowly leaks it into the ground, thus recharging the aquifers and enabling the village wells to sustain a reliable supply all through the dry season.
Many African countries have similar systems, based on the common sense knowledge that open bodies of water evaporate very quickly in hot climates. The number of people in India alone who rely on this science to stay alive is probably larger than the total population of the US.
Driven to distraction
Paul Marks quite rightly points out the risk to drivers of too many on-board warning systems and the confusion from head-up displays (28 October, p 30). However, I have been trialling an Australian invention that uses GPS and a clever method of storing speed-zone information to alert drivers, with a simple beep, when they exceed the speed limit. It also announces school zones and speed camera locations.
I have found this an excellent driving aid. I do not need to look at a screen 鈥� I simply decrease my speed until the beep stops. If I do get confused about the current speed limit I glance at the screen. This is actually less of a distraction than looking around for roadside speed limit signs on unfamiliar roads.
Ten years ago I carried out research on this topic for the New South Wales government. I concluded that the absence of speed advisory systems is a glaring oversight: at least 40 per cent of serious accidents involve one vehicle exceeding the speed limit shortly before the collision.
The editor writes:
Fair point, but adding more machines that go beep surely only adds to the problem. Imagine a lane departure alarm and a pedestrian detector beeping at the same time 鈥� this 眉bercool GPS speed alarm would not only cause confusion, it would be swamped.
Smallpox tender
In your article on biodefence you state: “An order is also expected for 20 million doses of an improved smallpox vaccine from the Danish firm Bavarian Nordic” (7 October, p 18). In fact, two companies have bid for this order: Acambis is the other. Both companies have an equal shot.
Ways of seeing
John Richards writes that “science is the only tool” for answering questions (28 October, p 26). But of course it is only a tool for answering scientific questions.
When we ask about the wider connection of our various concerns we need the whole toolbox, and it has to include an imaginative background.
For instance, if we raise questions about our relation to the living creatures around us, we may see them in many ways: as fellow beings that share our destiny; as resources handed to us to exploit; as machines operating in a vast, meaningless factory; or just as statistics in a book.
If we do not even grasp that more than one such way of seeing is possible we may remain stuck for life in the first position that occurs to us, priding ourselves on our purity and objectivity. This, as Robert Cailliau points out on the same page, is the source of dogma. And it is in order to avoid this disaster 鈥� not just to produce handy scientific hypotheses 鈥� that we need imaginative thinking.
How green is my roof
I was interested by the article about urban heat islands (28 October, p 58). “Green” roofs are used to combat climatic extremes in America and continental Europe 鈥� and they also provide habitat for so-called “brownfield” species. These roofs, covered with materials such as crushed brick, provide insulation, minimising heat loss in winter and overheating in summer. They also filter particulate matter and slow down the rate at which rainwater enters the drainage system. It is a pity they are not more common.
Nanohazardicity
I am somewhat perturbed by this whole nanohazard malarkey (Feedback, 4 November). There does not appear to be an SI unit of hazard, and so the precise amount of hazard constituted by a nanohazard is as yet undefined. A quick look at the reports available from the Royal Society for the Prevention of Accidents at informs us that in 2002, 4080 accidents were caused in the home by a curtain.
This would seem to present a good candidate for an SI unit 鈥� many people are exposed to a curtain on a regular basis, and 4080 accidents annually constitutes a significant level of hazard. I therefore propose the curtain as the SI unit of measurement for hazard.
Interestingly, a very quick scan through the statistics reveals that an air bed or lilo constitutes a hazard of almost exactly 1 centicurtain. The data set is large enough only to measure hazards down to 5 millicurtains 鈥� the hazardicity of an artist’s brush.
If we had a study of a billion people, and found precisely one instance of a particular home injury in one year, then we would have found a 1 nanocurtain hazard. We could then finally place a nanohazard warning sign upon the item, to alert the populace to its level of hazard.
I implore the government to commission such a study as a matter of urgency.
For the record
鈥� It’s neurons not neutrons in babies’ brains that seem to affect their susceptibility to SIDS (4 November, p 12). An extra “t” erroneously appeared in the text in one of the diagrams.
What the bleep?
Marcus Chown repeats the claim that the drama-documentary What the Bleep Do We Know? released in 2004, “is the fifth-biggest-grossing documentary in the US” (19 August, p 47). Can anyone tell me the source of this information? It seems extraordinary. based on what I’ve read.
The editor writes:
鈥� If you accept the film as a documentary, and the producers’ statement that it has taken $12 million, then at the time we checked it would rank sixth among all documentaries since 1981. That industry statistics site, however, does not appear to list the original film. It categorises the re-cut What the Bleep?: Down the Rabbit Hole, released in February 2006, as “comedy/drama”, and records total US box-office takings (in mainstream cinemas) at the considerably lower figure of $138,913 therefore ranking it 6482 among all films and 187 on the documentary rankings. ().
Look upon our works, ye mighty, and despair
The extensive damage humans have inflicted on our planet could easily be detected by an inquisitive alien even in the very distant future, in ways that Bob Holmes does not mention when he imagines an Earth without people (14 October, p 36).
In mediaeval times rich mineral deposits could be found at or near the surface of the Earth, accessible with hand tools. Even a hundred years ago commercial copper mines were extracting ore containing 25 per cent metal. These deposits have now been worked out and today a yield of 0.5 per cent is considered satisfactory. The situation is similar with many other metals. The continued supply of minerals that we take for granted is dependent on ever larger, deeper mines and continually improved extraction techniques.
These high-grade deposits formed over tens or hundreds of millions of years and presumably would re-accumulate very slowly if at all. It is most improbable that a large-scale industrialised civilisation could have existed before us and left these resources untouched.
The alien visitor in a million years time may well find an empty sterile planet, but she, he or it will have to dig deep if looking for mineral wealth.
From Bob Muirhead
Bob Holmes implied that anthropogenic CO2 emissions would cease almost at once if human beings suddenly disappeared from the planet. This assumption is unwarranted.
Existing large inventories of gaseous and liquid hydrocarbons in refineries, chemical plants and storage facilities would be released to atmosphere as those untended facilities failed due to fire, accidents and operational upsets. We could expect such releases to occur over weeks and months, possibly extending to a few years as all equipment progressively failed.
That would not be the end 鈥� or even the worst 鈥� of hydrocarbon releases. Larger releases would follow over succeeding decades, as equipment controlling all the oil and gas wells on land and under the sea failed due to corrosion, fire or other accidents. Essentially all the hydrocarbons in all the producing fields would be released to atmosphere. This would occur rapidly at first until field pressures fell to atmospheric, but even afterwards residual evaporation would still occur.
On longer timescales, the wells themselves would probably collapse, but cracks and fissures would still allow continuing seepage of hydrocarbons.
All the hydrocarbons thus released would form CO2 either by combustion in the inevitable fires or by other chemical reactions in the atmosphere and oceans.
Port Melbourne, Victoria, Australia
From Alex Saragosa
I believe other things may survive us, giving future alien archaeologists clues about our civilisation.
For instance, the tens of tons of gold stored in place like Fort Knox or the Federal Reserve of New York could survive intact for many millions of years. Maybe some would even preserve the symbols engraved on them. Even if not, the fact that so rare a metal is so heavily concentrated in a few places would clearly be a clue of artificial activity.
Maybe an alien archaeologist would scratch their head (if they had one) trying to understand why this strange civilisation hoarded gold. It could be as puzzling as our probes on the moon.
Terranuova, Italy
From Tony Smullin
Holmes states that “…left once more to its own devices, Nature would begin to reclaim the planet…” thus implying, as so many supposedly scientific articles do, that humankind is separate from nature. Also mentioned is human “interference” with ecosystems. How can we interfere with an ecosystem that we are vitally a part of?
Though mostly written by people who would argue against intelligent design or special creation, these types of statements tend to reinforce the idea. If natural evolution is true, then the works and waste of mankind are as natural as any anthill or beaver dam and should never be referred to in any way as being outside of nature.
Everett, Washington, US
Doctrine of signatures
Has Feedback any plans for a series of examples of the “doctrine of signatures”, on the lines of liverwort being an example of a plant that resembles the body part it is supposed to have the power to treat (7 October, p 56)?
If so, you need look no further than Digitalis purpurea, otherwise known as foxglove, whose perfectly heart-shaped fruit is the original source of the heart drug of the same name, and all its derivatives. The pity is that the medieval apothecaries following the doctrine of signatures never spotted this particular clue, and the medical usefulness of the plant was only discovered by chance.
Does this give the lie to the notion of God providing signs to guide people to appropriate remedies? Or does it argue for a creator with a warped sense of humour?
Schr枚dinger's quote
I have been researching the source of a quote attributed to the physicist Erwin Schr枚dinger: “The task is not so much to see what no one has yet seen but to think what no one has yet thought, about that which everybody sees.” It is often used in physics articles.
It appears that this quote is also attributed to the 19th century German philosopher Arthur Schopenhauer. Ludwig von Bertalanffy’s 1952 Problems of Life has been cited as a source attributing Schr枚dinger as the author, but on page 1 it attributes the quote to Schopenhauer. Is this a case of a superposition of Sch’s? Does anyone know the real source of this quote?
Patient concern
I agree that there is huge cause for concern in drug companies cosying up to patients’ groups (28 October, p 18). Such small charities, especially those supporting people with mental illnesses, are often naive, well-intentioned and penniless 鈥� leaving them vulnerable to the smooth operations of the drugs companies.
When I edited an in-house magazine for a small mental-health charity I rejected copy that was, to all intents and purposes, advertising for a drug company that “supported” the charity. The firm wanted a place in the mag for information about its product, in exchange for funding the magazine to the tune of 拢11,000.
Scratch the surface of most mental-health charities in the UK and you’ll find drug company money. I can’t help feeling that he who pays the piper… There are so many other treatment options than drugs, with far fewer risks and better outcomes 鈥� but drugs dominate. I wonder why?
From Susan Resko, Child and Adolescent Bipolar Foundation
Had your article on disease-mongering among patient advocacy groups focused its lens on toenail fungus or erectile dysfunction, you might have had a compelling argument. But brain illnesses such as bipolar disorder have peer-reviewed, evidence-based treatments, and this is not new science. To call it disease-mongering is to perpetuate stigma and prevent patients from receiving life-saving treatment.
Why criticise the pharmaceutical industry for attempting to assist the very people from whom they make billions? Industry has an ethical obligation to support those who suffer from illnesses they treat, and to support patient groups because it’s the right thing to do.
I am extremely grateful to the pharmaceutical industry; without it, I would have lost a son, a mother and a husband to suicide, stroke and heart disease respectively. Patients and their families value the easy access to information their foundations provide them.
Wilmette, Illinois, US
From Georgianna Bell, Restless Legs Syndrome Foundation
The Restless Legs Syndrome Foundation vehemently denies the accusation that non-profit groups like us that accept monies from pharmaceutical companies are actually puppets for these same companies 鈥� extensions of their mission instead of dedicated to achieving our own. Our publications are carefully scrutinised and approved by our medical advisory board, which is made up of leading healthcare providers and researchers.
Rochester, Minnesota
The editor writes:
We did not choose to focus on any disorder. We took a random sample of patient groups, and added groups with revenue of at least $100,000 that focus on conditions dealt with in the Public Library of Science Medicine issue on disease-mongering. Many patient groups, like the RLS Foundation, stress that the information they provide is vetted by a medical advisory board. But these boards may also have financial ties with drug companies. A Google search reveals that a majority of members of the RLS Foundation’s medical advisory board have served as consultants to GlaxoSmithKline, which makes Requip, used to treat RLS.