Self regarding
I am blind. My guide dogs sleeps in her own bed in our bedroom.
Some time ago my wife and I bought wardrobes with mirror doors. On the first
day that these were in the bedroom, the dog seemed quite startled by them. She
clearly recognised another dog but was puzzled by the lack of scent
(17 June, p 30).
She was also puzzled by the image of my wife, who was standing behind her,
and stared at this intently for some time. My wife waved her fingers and the
dog’s head immediately whipped round as if to confirm that this was what had
caused the change in the image. She then turned sideways and stretched, without
taking her eyes from the image. This seemed to satisfy her and she settled down
to sleep.
For several months after this, she sat before the mirror every night at
bedtime and would not get into her bed until my wife had come up behind her and
waggled her fingers at the mirror. I am not sure what this says about her sense
of self, but it seemed clear that she could recognise the reflection of my wife,
and understood that what my wife did affected what happened in the
reflection.
Citizens watch
I’m afraid your revolutionary idea to have CCTV cameras fed to the Web with
links to report suspicious activity or crime
(Feedback, 17 June)
has been available for two years at www.irational.org/cctv.
The site, which does pretty much as you describe, was created by doyen of Net
art and activism, Heath Bunting.
Letter
Your idea forms a large part of Earth by David Brin and is the basis
of his book The Transparent Society, an article on which can be found
at: www.wired.com/wired/archive/4.12/fftransparent.html.
Correction
In “Global Brain”
(24 June, p 22)
we implied that the Principia Cybernetica project was the work of Johan
Bollen. In fact it has existed since the first days of the Web. Bollen, employed
by the Active Recommendation project at Los Alamos, supplied some of the
algorithms used by Principia Cybernetica.
Giving a lift
Bernoulli’s principle is invoked to explain lift in Inside Science
(17 June).
But Bernoulli fails to explain, for example, why stunt planes with symmetrical
wing sections fly.
The correct explanation is partly given: indeed, the deflection of air mass
by the wing is the primary cause of lift. There is also a secondary and less
well-known reason at play called the Coanda effect. This is why fluids “stick”
to surfaces. You can demonstrate the Coanda effect by holding a glass sideways
under a slowly running tap. The water hits the surface of the glass, clings to
it, and then dribbles off the bottom.
On a wing with a more prominently curved top surface, air “sticks” to the
upper side and is deflected downwards due to Coanda.
This produces a net momentum transfer downwards, aiding the lift process.
Some aircraft exploit this effect, mounting engines in front and above the wings
to enhance lift using the jet exhaust.
Letter
Your article says: “Air travelling across the upper surface has to follow a
slightly longer path…This means that air above the wing moves faster than the
air below it.” Though it is true that air above the wing both follows a longer
path and travels faster, there is no causal effect between the two statements.
The faster air velocity is a consequence of the reduced pressure, not its
cause, and the difference in pressure is also the reason why the air stream is
deflected downwards. The pressure difference across the wing is simply a
consequence of the flow geometry.
Phantom hearing
For audiologists, the equivalent of an amputated limb is hearing loss
(17 June, p 26).
Tinnitus frequently accompanies hearing loss, and can be compared
to phantom pain. One of my clients was troubled by unilateral hearing loss and
tinnitus after the acoustic nerve was severed surgically. She was fitted with a
hearing-aid system that picked up sound with a microphone at the “dead” ear and
delivered it to a speaker coupled to the good ear.
Instantly she felt the dead ear had returned to life, and the tinnitus
disappeared. One intriguing aspect of this was the ability of a single auditory
nerve to supply the brain with an analogue of two separated ears.
Phone check
If mobile phones are really dangerous on aeroplanes
(27 May, p 7),
why don’t the airlines check for switched-on mobiles before take-off? It is very easy to
detect a mobile that is receiving a call, so surely it must be straightforward
to pick up the identification pulses that they send out every few seconds.
The Civil Aviation Authority’s report on mobile phones also recommends that
“airlines evaluate mobile phone detection equipment which would warn crews if a
phone was in use”. Such systems are already in use in restaurants and theatres
to prevent mobile users ruining other people’s evenings out鈥擡d
Consult the patient
I’m not sure how Nell Boyce can diagnose from across the street “this
obviously schizophrenic man”
(17 June, p 49).
I do agree that this is all bound up with our social and cultural values.
My answer to her question of how we decide who needs to take psychotropic
drugs is that, like any other treatment, we offer it to the customer and let
them choose.
Universal name
If we are to debate the big cosmological questions such as, “Why do the
physical constants happen to take values which allow life to exist?”
(10 June, p 32),
we must first ensure that the language we use is clear and precise and
agreed by all participants. That means avoiding terms such as “multiple
universes” for a start.
The Universe is, by definition, all-encompassing, unless someone has
unilaterally altered this definition, which would seem pretty pointless since we
would still need a word for the sum total of all the little “universes”.
Chown appears to acknowledge this at one point, since he refers to these as
“regions” instead. And earlier in the article, he slips into “the observable
Universe”, quoting a theory which uses this term to describe one of the
“multiple universes” whose sibling universes may simply be a very long way
away.
I am by no means convinced that we can describe, let alone explain, the laws
of physics in anything but mathematical terms. But if we are going to try to put
them into words鈥攚hether we are talking about the anthropic principle,
nine-dimensional strings or an infinite array of giant tortoises鈥攕houldn’t
we first make sure we agree on what the words mean?
Marcus Chown writes: This is a common problem. The Universe used to refer
only to the Sun and the planets. By the 1920s it referred to the Milky Way. Now
we think of it as the galaxies鈥攂ut it is undergoing yet another
metamorphosis.
Only science knows
In your interview with Satish Kumar
(17 June, p 46),
he is quoted as saying that “there are other ways of
knowing about the world鈥攑hilosophical,
religious, poetic, artistic, cultural”. He also says that science “is only one
way of knowing” or, as the interviewer rephrased it, that science may be one
route to knowledge.
Kumar’s first statement is not true: emotions, opinions, beliefs, intuitions
and myths are all vital to our cultures and our spiritual well-being, but are
not knowledge. Their study may be validated as knowledge, but that does not
prove that they are.
Kekul茅 may have seen the structure of benzene in a dream, but that
dream did not in itself constitute knowledge. A psychologist’s diagnosis of the
ravings of a madman may aspire to the status of knowledge, but the ravings do
not.
His second statement is true in the sense that there may be several routes to
knowledge as there are roads to a named city, but, however complex and evolving,
there is only one knowledge as there is only one such city.
When people like Richard Dawkins and E. O. Wilson say that there is no other
knowledge but scientific knowledge, they simply mean that, whatever the object
of one’s investigation, be it a natural or cultural phenomenon, a rock or a
poem, and whatever the motivations for such a study, knowledge of this object
can be gained only through the time-tested methods of rational inquiry, logical
thinking, careful collection and sifting of evidence, experimentation if
required, and public scrutiny. If we call this methodology “science”, then
science is the only way of knowing.