John Gribbin, Author at New 女生小视频 Science news and science articles from New 女生小视频 Tue, 04 Feb 2025 22:05:13 +0000 en-US hourly 1 https://wordpress.org/?v=7.0.2 242057827 The 100-year-old symmetry theorem that is still changing physics today /article/2466657-the-100-year-old-symmetry-theorem-that-is-still-changing-physics-today/?utm_campaign=RSS|NSNS&utm_content=currents&utm_medium=RSS&utm_source=NSNS Tue, 04 Feb 2025 14:00:20 +0000 /?post_type=article&p=2466657 2466657 Big Weather /article/1853875-big-weather/?utm_campaign=RSS|NSNS&utm_content=currents&utm_medium=RSS&utm_source=NSNS Fri, 21 May 1999 23:00:00 +0000 http://mg16221878.400 1853875 Bolts from the blue /article/1850980-bolts-from-the-blue-2/?utm_campaign=RSS|NSNS&utm_content=currents&utm_medium=RSS&utm_source=NSNS Fri, 11 Sep 1998 23:00:00 +0000 http://mg15921518.900 1850980 Review : It figures /article/1848945-review-it-figures/?utm_campaign=RSS|NSNS&utm_content=currents&utm_medium=RSS&utm_source=NSNS Sat, 28 Mar 1998 00:00:00 +0000 http://mg15721277.600 Research Methods: Guidance for Postgraduates edited by Tony
Greenfield, Arnold, 拢14.99, ISBN 0340646292

THIS just might be the most useful book any new postgraduate contemplating
research could ever buy. Research Methods is packed with practical,
common-sense advice about everything from sources of funding and statistical
methods, to writing up your thesis.

Much of this is at the level of the blindingly obvious鈥攚ith hindsight,
that is. In practice, it is likely to be a lifeline for someone struggling to
get to grips with a new way of life.

Other advice shows sophisticated insight into such things as sampling
methods. And some consists of brutal examples of how not to do research. I
particularly enjoyed Tony Greenfield鈥檚 own contribution to methodology,
reporting a true story about what happened when he was asked what could be made
of a medical study in which there were only 32 subjects in a survey, instead of
the recommended 150, and only 7 of them turned out to meet the criteria of the
study. The brutal truth in this case is that the study was worthless.

The point hammered home throughout the book is the need for honesty in
research鈥 including honesty with yourself鈥攁nd avoiding wishful
thinking.

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Review : How not to do it /article/1847133-review-how-not-to-do-it/?utm_campaign=RSS|NSNS&utm_content=currents&utm_medium=RSS&utm_source=NSNS Sat, 10 Jan 1998 00:00:00 +0000 http://mg15721165.000 Tricks of the Trade by Howard S. Becker, University of Chicago Press,
拢27.95/$35, ISBN 0226041239

HAVING recently returned to research (only part time, but still) after a long
spell as a journalistic poacher of research done by others, I fell upon Howard
Becker鈥檚 book with cries of delight. Subtitled How to think about your
research while you鈥檙e doing it, it looked like just the thing I needed to
get up to speed.

I was sadly mistaken. The research Becker is concerned with is social science
(which I thought, and still tend to think after reading this book, is something
of an oxymoron). The tricks of the trade come, we are told, from 鈥渁 variety of
fields such as art history, anthropology, sociology, literature and philosophy鈥.
Yes indeed, and no doubt the anthropologists are embarrassed by the company they
are keeping here.

The fact that the book turned out to be of absolutely no use to me at all in
my contribution to a new determination of the age of the Universe does not,
though, mean that it is not sorely needed by the audience to which it is
addressed.

But this is not a cause for rejoicing in the ranks. In one telling example of
the standards of 鈥渟cientific鈥 investigation used by the social scientists,
Becker describes a project in which the 鈥渟cientists鈥 analysed the social status
of the participants in weddings announced in The New York Times
each June over several years. One of their portentous conclusions was
that no Jewish weddings were announced in their sample. They hadn鈥檛 realised
that June always falls within one of two Jewish holy periods when religious Jews
do not get married. Such pathetic inability to check the facts would have been
disgraceful during my time as a journalist, let alone as a scientist鈥攜et
Becker finds it necessary to hold the example up as a warning to social
scientists in the 1990s.

It鈥檚 a great shame that Richard Feynman has not lived to see this book, and
to offer his comments on it鈥攚ere he to have been bothered. One of the
anecdotes Feynman liked to tell involved a colleague of his who was running maze
experiments with rats, to test a hypothesis about what made the rats turn left
or right at a T-junction.

Feynman, out of the kindness of his heart, helped out with the statistics.
The research didn鈥檛 show what the experimenter was looking for but after the
experiment had been carried out, the colleague returned in great excitement,
having discovered a run in which the rat had alternated its choice at every
junction of the maze鈥攆irst left, then right, then left, and so on. Surely
the odds against this must be huge?

Patiently, Feynman tried to explain that the way to test the hypothesis that
rats do (or don鈥檛) alternate left and right turns is to formulate the hypothesis
first, then carry out the experiment(s). You can鈥檛 choose one odd result from a
pile of data and claim it has particular significance. But his colleague, we are
told, never did get the point.

The tricks that Becker describes are on the same level. They are things that
real scientists learn in the cradle, and use by instinct when doing the
research. Judging by this book, any physicist threatened by cuts in funding
ought to consider a career in the social sciences, where it ought to be possible
to solve the problems the social scientists are worked up about in a trice. Or,
just maybe, to show that they are talking a lot of hot air. Either way, that
would release funding which could then be used to counter the cuts in
physics.

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Review : Mercury’s ghostly companion /article/1845148-review-mercurys-ghostly-companion/?utm_campaign=RSS|NSNS&utm_content=currents&utm_medium=RSS&utm_source=NSNS Fri, 20 Jun 1997 23:00:00 +0000 http://mg15420875.700 VULCAN, a planet orbiting within the orbit of Mercury, was invoked by
19th-century astronomers to explain discrepancies between the predicted and
actual orbit of Mercury. The astronomers were inspired by the spectacular
triumph of Urbain Le Verrier in showing that the orbit of Uranus was due to the
gravitational influence of another planet. The other planet, named Neptune, was
discovered in 1846 exactly where he had predicted.

Both sets of calculations were based on Isaac Newton鈥檚 theory of gravity. We
now know that the small difference between the predicted and actual orbit of
Mercury shows the beginning of the breakdown of Newtonian theory in strong
gravitational fields. Albert Einstein鈥檚 general theory of relativity
spectacularly provided a theory of gravity that goes beyond Newtonian theory,
precisely predicting the observed orbit of Mercury. Little point, you might
think, in writing about the search for Vulcan.

Richard Baum and William Sheehan just about prove that assumption wrong.
In Search of Planet Vulcan (Plenum, $28.95, ISBN 0 306 45567 6)
begins with Greek speculations about the nature of the planets, zips through the
story of Newton鈥檚 contribution without adding anything to the traditional
version, and runs through the discoveries of the outer planets.

The meat of the book is the story of Le Verrier鈥攏ot just his ideas
about Vulcan, but the discovery of Neptune (with credit given to the parallel
work of John Couch Adams). We are almost halfway through before we get to the
story of Vulcan, which is enlivened by discussion of the claims that the
hypothetical planet had been observed, a triumph of expectation over fact which
is a salutary lesson to all scientists.

The story is timely as astronomers spot planets orbiting other stars, using
the techniques that Le Verrier used to probe the then unseen parts of the Solar
System.

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Review : All about consciousness /article/1845431-review-all-about-consciousness/?utm_campaign=RSS|NSNS&utm_content=currents&utm_medium=RSS&utm_source=NSNS Fri, 30 May 1997 23:00:00 +0000 http://mg15420845.900 WHAT a treat it is to find an engaging writer who makes complicated issues
clear and throws open specialist byways of science to everyone. Not that the
nature of consciousness is exactly a byway of science鈥攊t has recently been
thoroughly debated in public by writers such as Roger Penrose and Daniel
Dennett, although none of the previous contributions is as accessible as James
Trefil鈥檚 Are We Unique? (Wiley, 拢18.99, ISBN 0 471 15536 5). He
argues that our kind of consciousness is indeed unique, and quite different from
the kind of consciousness that may before long be achieved by machines. But a
large part of the attraction of his book is that he does not ram his views down
your throat. Instead, he presents a lucid discussion of how the brain works and
what consciousness is, before offering you his interpretation of the evidence
and its implications. Even if you do not agree with his conclusion (and I do
not), the book offers much entertainment and information.

Clarity and a refusal to be fooled by seductively offered, but insecurely
founded, ideas are the hallmarks of Trefil鈥檚 work. Doubtless this is a tribute
to his background in physics. He provides one of the most thorough and
persuasive critiques of the often extravagant claims about the ability of other
species, notably chimpanzees, to use language that I have seen. He also provides
a clear summary of how evolution works. And he makes the point that the
possibility that human intelligence is a unique attribute does not make us any
more special than the fact that the octopus, for example, is unique. Being
unique does not place us outside evolution, or outside the scope of scientific
investigation. This is said with more force than seems necessary, but perhaps he
is responding to the claims of creationists in the US.

At the heart of Are We Unique is Trefil鈥檚 explanation of why the
human brain is not the same as an electronic computer, and his persuasive
argument that our kind of intelligence and consciousness has to do with the
physical complexity of our brains. The key point here is that there may well be
a threshold of complexity above which consciousness kicks in, so that even if
the brain (specifically the cerebral cortex) of another species has, say,
one-hundredth of the complexity of a human brain, that does not mean that an
individual member of that species has 1 per cent of our consciousness.
Consciousness is arguably an all-or-nothing phenomenon that switches on at some
level of complexity.

It is this kind of discussion that leads Trefil to the conclusion that our
form of intelligence is not the same as machine intelligence. I would agree with
this up to a point. But Trefil fails to address the fact that if improvements in
computing continue at the present rate for a few more decades, it will be
possible to build a machine that simulates the way a human brain works, right
down to the neurons, with all the complexity of a human brain. It might be
expensive and wasteful of computer power, like the simulator I can run on my
PowerMac that makes it pretend it is a ZX Spectrum. I see no reason, however,
why such a virtual brain should not achieve exactly the same kind of
consciousness as the human brain, even if you will never manage to do this
simply by adding more RAM to your home PC.

But in all probability I would never have thought of this if Trefil had not
led me by the hand through this version of what he understands by consciousness,
and the major role of complexity. It is a sign of just how good this book is
that about the only nit I can find to pick is that, although eclectic enough to
include a discussion of Isaac Asimov鈥檚 three laws of robotics, it consistently
misspells the name of his robot detective, R. Daneel Olivaw. And if that is the
worst mistake in the book, you can imagine how good the rest of it is.

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Science : Mirror worlds may lurk in the dark /article/1844496-science-mirror-worlds-may-lurk-in-the-dark/?utm_campaign=RSS|NSNS&utm_content=currents&utm_medium=RSS&utm_source=NSNS Fri, 25 Apr 1997 23:00:00 +0000 http://mg15420792.800 HUGE globs of exotic hydrogen from a mirror universe are the latest quarry in
the hunt for the mysterious dark matter that fills the Universe. They could also
explain why far fewer neutrinos than expected emerge from the Sun.

Rabi Mohapatra and his colleagues at the University of Maryland in College
Park followed up an idea that dates back to the 1980s. This was that every
elementary particle has a partner in a mirror world, an idea that would help
tidy up theories of how the four forces of nature acted as one just after the
Universe was born.

The two components, each made up of its own set of fundamental
particles鈥攕uch as the electron and the three normal types of
neutrino鈥攚ould be mixed up. The force of gravity could easily clump all
the mirror matter into mirror stars and mirror planets. But that would be the
only force of our world that they would feel. Mirror matter would not feel the
electromagnetic force, so mirror stars would be invisible.

Mohapatra realised that if one of the three neutrinos that would exist in the
mirror world was much heavier than its everyday counterpart, this could explain
why the Sun鈥檚 nuclear reactions produce only a third of the neutrinos that
theory predicts.

Physicists have suggested that the reason for this is that the type of
neutrino expected from nuclear reactions is turning into the two other normal
types鈥攚hich are as yet undetectable鈥攅n route to the Earth. This
happens through a so-called oscillation鈥攖wo or three neutrinos are
effectively 鈥渕ixed up鈥 and flip from one type to another over a regular
distance. Some inconclusive evidence for this comes from detectors at Los Alamos
National Laboratory in New Mexico (see 鈥淐osmic changelings鈥, New
女生小视频, 16 March 1996, p 28).

The oscillation distance of the neutrino mixture depends on the masses of the
neutrinos involved. The masses of everyday neutrinos seem too small to allow
oscillations over the distances that would explain the solar neutrino problem.
But a fourth, heavier neutrino from the mirror universe could interact with the
normal neutrinos through gravity and make the oscillation distance just right,
says Mohapatra.

Now, working with his colleague Vigdor Teplitz of the University of Maryland,
Mohapatra has looked in detail at the implications of this theory for the mirror
universe (Astrophysical Journal, vol 478, p 29). If the mirror world
contains a heavy neutrino, it turns out that beta-decay鈥攚hich involves
neutrinos鈥攊s much faster there. In that case, mirror neutrons would decay
so quickly that the only element that could exist is mirror hydrogen.

Without neutrons, nuclear fusion would be impossible, so there would be no
stars, says Mohapatra. As the Universe expands, the mirror hydrogen would clump
into 鈥済lobs鈥 the size of dense star clusters. The globs would form
part鈥攑erhaps all鈥攐f the invisible 鈥渄ark matter鈥 that exerts a pull
on stars and galaxies. Mohapatra adds that the idea can be tested, because the
globs would bend the light from background galaxies and focus it just like a
lens.

Rocky Kolb of Fermilab, near Chicago, calls Mohapatra鈥檚 work 鈥渁 really nice
study鈥, and adds that it could help to extend the current Standard Model of
particle physics. 鈥淭here seem to be several loose threads fraying at the edges
of the Standard Model, and nobody is sure which one to pull to make the model
unravel,鈥 he says. 鈥淧erhaps this is it.鈥

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Science : Yes, dashing for cover is the way to stay dry /article/1843772-science-yes-dashing-for-cover-is-the-way-to-stay-dry/?utm_campaign=RSS|NSNS&utm_content=currents&utm_medium=RSS&utm_source=NSNS Sat, 29 Mar 1997 00:00:00 +0000 http://mg15320752.300 IF YOU are caught in a downpour, it is better to run for shelter than walk,
researchers in the US advise. This may sound obvious, but an earlier study in
Britain suggested that you would get just as wet running as walking.

In 1995, Stephen Belcher of the University of Reading and his students
calculated how much water falls on top of your head and how much you sweep up on
your front as you move forward (Weather, vol 50, p 367). Obviously, you
would get wettest standing still, and less wet the faster you moved. But the
Reading team found that the benefits of running faster than about 3 metres per
second鈥攚hich they described as a walking pace鈥攚ere tiny.

Thomas Peterson and Trevor Wallis, meteorologists at the National Climatic
Data Center in Asheville, North Carolina, had a hunch that this was wrong. They
realised that the Reading team had overestimated the average walking pace, so
they reworked the calculations for a walking pace of 1.5 metres per second and a
running speed of 4 metres per second.

Peterson and Wallis conclude in the latest issue of Weather (vol 52,
p 93) that a walker would get 16 per cent wetter than a runner over a distance
of 100 metres in drizzle. In heavy rain, this would rise to 23 per cent. When
the researchers allowed for the way that runners tend to lean forward,
sheltering the front of their bodies but increasing the rainfall on their backs,
they found that a walker would get 36 per cent wetter than a runner in heavy
rain.

Not content with theory alone, Peterson and Wallis decided to test their
ideas. 鈥淚f verification requires an $80 million satellite, one may have
to forgo verification,鈥 says Peterson. 鈥淏ut if it involves a simple experiment,
that鈥檚 another matter.鈥 Peterson and Wallis are roughly the same size. Wearing
identical clothing, one ran 100 metres in heavy rain and the other walked.

They weighed their clothes before and after the experiment. This showed that
the walker had absorbed 0.22 kilograms of water, while the runner had soaked up
only 0.13 kilograms. This is about 40 per cent less, in line with the model鈥檚
predictions.

Belcher says that his team鈥檚 work was a bit of fun, and that apart from the
confusion over what a typical walking speed is, their results were similar to
those of Peterson and Wallis. 鈥淚鈥檓 delighted to see that their experiments gave
results in qualitative agreement with the model,鈥 says Belcher.

But why not just take an umbrella? For anyone thinking of taking the easy way
out, Wallis has a warning: 鈥淩unning with an umbrella has a negative impact on
your aerodynamics.鈥

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Science : Making waves while the Sun shines /article/1842779-science-making-waves-while-the-sun-shines/?utm_campaign=RSS|NSNS&utm_content=currents&utm_medium=RSS&utm_source=NSNS Sat, 08 Feb 1997 00:00:00 +0000 http://mg15320682.500 THE Sun pelts Earth with far fewer electron neutrinos than most models of
solar structure predict. That fact has left scientists with a dilemma known as
the solar neutrino problem. Either the standard physics used to model the
structure of the Sun is wrong, or the physicists who think they know how
neutrinos behave are wrong.

Now a detailed study of waves on the star鈥檚 surface has revealed almost
perfect agreement with models of the Sun鈥檚 structure. The standard physical
description of the Sun seems to be safe. It is the particle physicists and their
ideas about neutrinos who need to revisit the drawing board.

The temperature at the Sun鈥檚 core is an important piece of the solar neutrino
puzzle. The core would generate electron neutrinos at the detected
rate鈥攁bout one-third of that predicted by models鈥攊f it was even 10
per cent cooler than physicists believe. But physicists cannot directly measure
core temperature to that accuracy.

Instead, John Bahcall of the Institute for Advanced Study in Princeton, New
Jersey, and colleagues elsewhere in the US and in Denmark used new measurements
of the waves that appear on the Sun鈥檚 surface. The team determined, based on the
waves鈥 trajectories, which of these would pass through the core of the Sun.
These revealed its temperature and structure rather as details of the interior
of Earth can be gleaned by studying how earthquake waves pass through it. Their
observations match the standard solar model to an accuracy better than 0.2 per
cent (Physical Review Letters, vol 78, p 171). 鈥淚 find the precise
agreement just stunning,鈥 says Bahcall.

This dramatic achievement shows that electron neutrinos must be disappearing
before they hit Earth. Some physicists have already speculated that they might
convert to other flavours of neutrinos鈥攖he muon and tau (鈥淐osmic
changelings鈥, New 女生小视频, 16 March 1996, p 28).

John Ellis, a particle physicist with CERN, accepts that the next step is up
to those in his discipline. 鈥淭he solar neutrino problem cannot be solved by
tinkering with the standard model of the Sun.鈥

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