Letter
Did anyone report a small tornado appearing above Podkletnov’s laboratory? I
would have expected that, with the column of air above the anti-gravity wheel
being 2 per cent lighter than the surrounding air, it would have started to
rise, been replaced by heavier air, which would have also started to rise,
resulting in a minor tornado or at least a dust devil without the benefit of
dust. No?
On the other hand, I wonder why the device wasn’t peddled as a perpetual
motion machine. Simply place a heavy wheel with its axis horizontal and part of
its rim above the device. That part of the rim would get lighter and the wheel
would start to rotate. Perpetual motion! Perhaps even NASA would have bridled at
spending $600,000 of the taxpayer’s money for a perpetual motion machine.
Antigravity sounds more scientific, perhaps.
Letter
The anti-gravity machine described in Podkletnov’s 1992 paper seems to be
almost identical to the gravity generators used on the starship Enterprise, as
described on page 144 of Star Trek: The Next Generation Technical
Manual, by Rick Sternbach and Michael Okuda, copyright Paramount Pictures
1991鈥攅xcept that the Star Trek devices have larger
superconducting discs and spin a lot faster. Of course, that can only be a
coincidence, can’t it?
When I was a pig
I recently watched a television programme on “cell memory”. It claimed that
recipients of human organs were experiencing memories of the donors’ likes and
dislikes鈥攚ithout knowing anything about the donor. Although very
controversial, many of the case studies were shocking and seemed unlikely to
have been coincidence.
This raises an interesting question regarding xenotransplantation
(12 January, p 7).
Would the human recipient suddenly have a strong desire to roll
around in the mud and eat swill?
Starve a cold
I believe you have missed the point in your article about feeding a cold and
starving a fever
(19 January, p 15).
You’re not alone, as this saying is nearly always misquoted.
The saying should be: “If you feed a cold you will have to starve a fever.”
The theory goes that if you carry on eating when you have a cold, your body will
have to use up vital energy digesting the food rather than concentrating all its
energy towards fighting the cold. You are therefore more likely to allow the
cold to develop and become a fever. Your body will then have no option but to
shut down your desire to eat in order to direct all its energy into fighting the
fever.
Black stars
Pawel Mazur and Emil Mottola may or may not have come up with an interesting
new kind of astrophysical object
(19 January, p 26),
but their criticisms of the traditional black hole approach are way off the mark.
They claim that “a seemingly impossible feature is that photons falling into
a black hole would gain an infinite amount of energy by the time they reach the
event horizon”. This is not true. Their energy, as measured by a family of
observers that are stationary with respect to the horizon, will indeed approach
infinity as the horizon is approached, simply because the acceleration of that
family of observers itself approaches infinity.
Wolfgang Rindler of the University of Texas at Dallas has shown that one can
construct a family of observers in flat space-time which behaves in exactly the
same manner, so that any photon in flat space-time could then be said to acquire
an infinite amount of energy. But I presume that Mazur and Mottola are not
predicting that flat space-time “undergoes a quantum version of a phase
transition”.
An exact solution of the Einstein equations, discovered by P. C. Vaidya in
1943, describes the growth of a black hole when electromagnetic radiation
impinges on it. There is no problem with infinities, and no need to “dream up
far-fetched excuses”.
As for the observations reported in October last year鈥攐f a heavyweight
black hole emitting far brighter X-rays than theories predict鈥攖here is a
perfectly good explanation, the so-called Blandford-Znajek mechanism. This
involves magnetic fields and rotation鈥攂oth of which are to be expected in
a realistic astrophysical scenario鈥攁nd it extracts rotational energy from
the black hole itself.
Letter
Given that the proposed gravastars have a solid crust as opposed to the event
horizon of a black hole, material falling onto one would hit the crust rather
than disappearing beyond the event horizon.
Surely this would mean that a gravastar would vibrate under the shock of
impact, unlike a black hole. I suspect the vibration would be slight, given the
density of the crust, but it might be detectable and would give a mechanism for
differentiating such superdense bodies.
Jostling pollen
Astronomers may have seen the effects of black holes being jostled by stars
(19 January, p 10),
but the Scottish naturalist Robert Brown never saw the
effects of pollen grains being jostled by atoms.
Contrary to what many textbooks state, Brown actually observed the motion of
much smaller particles inside fluid-filled voids within the pollen grains. This
no doubt sounds like tiresome nit-picking, but as Einstein’s analysis of
Brownian motion shows, the effect is far smaller for relatively huge pollen
grains than it is for the particles inside them.
Confusing the two has in the past led to accusations that Brown could not
possibly have seen the effect which bears his name. It would be a shame to rob
someone of his claim to fame simply because textbooks can’t be arsed to get the
facts straight.
Hot air
It appears to me that James Tuck’s exploding Los Alamos bunker
(26 January, p 55)
is just one more demonstration that mixtures of methane and air are
explosive and can be detonated by a spark.
Didn’t Sir Humphrey Davey invent a miner’s lamp to avoid this very
possibility about two hundred years ago? When I grew up in the West Midlands in
the 1930s and 1940s, it was common knowledge that one should not go looking for
a gas leak with a lighted candle. Apparently this information had not reached
Los Alamos when Tuck carried out his experiment.
Correction
“Is this the one?”
(26 January, p 4)
stated that Catherine Verfaillie had injected both mouse
and human “multipotent adult progenitor
cells” into blastocysts to show that they are pluripotent. In fact, she injected
only mouse MAPCs.
Also, our article about the search for gravitational waves using pulsar timing
(19 January, p 17)
stated that LIGO (Laser Interferometer Gravitational Wave Observatory)
is funded by NASA. It is in fact funded entirely by the National Science Foundation.
Lastly, our article on the colour of the Universe
(19 January, p 16)
stated that star formation peaked “between 1 and 2 million years after the big bang”.
This should have read “1 and 2 billion years”.
Get it wrong to win
Erica Klarreich’s article on the Weakest Link quiz show was
interesting
(19 January, p 11),
but it addresses the best way for the team to
accumulate the most money in the bank, rather than how an individual player can
walk away with whatever has actually been banked.
For example, if there are three remaining contestants, and one is clearly
stronger than the other two, the two weak players may be inclined to vote off
the strongest to avoid losing in the final round, which involves a one-on-one
play-off. This suggests that a strategy for ultimately winning may involve not
answering every question correctly so as not to appear too threatening.
Furthermore, while the biggest pay-off may come from not banking too soon,
contestants who fail to bank any money are clearly penalised because they annoy
other players who do bank, and are thus subjected to a greater likelihood of
being voted off.
Consideration of the social and behavioural elements of the show would
certainly make any mathematical analysis more complex.
Sexy Lucky
Your article on Lucky the frog stated that I failed in my attempt to breed
from the last remaining pool frog in captivity in Britain
(12 January, p 42).
Not wanting the scientific and conservation communities to be left with the
depressing idea that the last British pool frogs died without issue, I need to
correct this statement.
Lucky was in fact extremely keen on the opposite sex in spite of being, in
frog terms, quite geriatric. So keen was he to keep the British end up, in fact,
he had to be prised off some of the European females in his outdoor enclosure
(for their own sake) after holding onto them in amplexus for three days
continuously.
The unsuccessful matings were with females of Swedish origin. I found this
particularly disappointing as, in the name of science, I had spent some of my
1997 summer holiday chasing Swedish females around a lake with a net in the hope
of getting breeding started (with clearance from the Swedish government).
Genetic work by myself at Greenwich University and by Inga Zeisset and Trevor
Beebee at Sussex University shows that Norway and Sweden have pool frogs that
are the closest genetically to those of Britain. The Swedish females showed no
interest in laying eggs, even though Lucky was firmly attached and waiting to
fertilise them. They also showed no interest in Swedish males and vice
versa.
My assumption is that an environmental trigger is missing when the Swedish
frogs are at British latitudes. Two females, of presumed Dutch origin, bred
quite happily with Lucky and to this day, Lucky’s genes persist in several
offspring.
Pool frogs belonging to Swedish, Norwegian and British populations seem,
however, to form a distinct genetic grouping (a “clade”). It was hoped that if a
mating with Lucky occurred with Swedish or Norwegian females, offspring of this
scientifically interesting clade could be released back into East Anglia.
Putting spin on it
I believe that any gravitational effect of Evgeny Podkletnov’s spinning
superconducting disc will be swamped by another effect
(12 January, p 24).
Einstein’s special theory of relativity predicts that the disc will produce an
“electrostatic” force on any nearby static charges. The effect is directly
proportional to how fast the disc is spinning, the current in the loop, and the
square of the disc’s diameter.
I calculate that the 145-millimetre disc, spinning at 5000 revolutions per
minute and carrying 1000 amps, will act like a static charge of 4.3
millicoulombs, equivalent to a 20-centimetre sphere carrying 380 kilovolts. That
could exert a significant force on any test mass or balance carrying a stray
static charge, and ions present in cold dry air would drive the reported air
currents. Normal electrostatic shielding will not work as expected.
Even if this is the only effect that Podkletnov has seen, it is still
valuable new science鈥攊t would verify a core element of special relativity,
and could perhaps be scaled up and exploited to create an ion drive.