- The end of the world really could be at hand, scientists
warned yesterday, and there are a number of ways it could happen, the British
Association science festival in Glasgow heard yesterday.
-
- A strange subatomic particle produced in an atom-smashing
experiment could, in theory at least, tumble to the centre of the planet
and start eating the globe from the inside out.
-
- Or a random quantum fluctuation in distant space could
switch off the machinery that makes matter massive, a step which would
trigger off a bubble of destruction that would advance at the speed of
light, shutting down all creation in its path.
-
- Or a 1km wide asteroid could sweep in from the southern
skies, hit Australia at 20kms a second and gouge out a crater 10km across,
throwing huge lumps of rock into orbit. Forty-five minutes later, blazing
fragments of Australia would begin to reduce Britain to ashes.
-
- The first two catastrophes were theoretically permitted
by present understanding of cosmic physics, said Benjamin Allanach, a researcher
at Cern, the giant particle accelerator in Geneva. The third, however,
was quite probable in any one year and inevitable in the long run, warned
Duncan Steel, an asteroid expert at the University of Salford.
-
- Dr Steel was the only non-American in a Nasa committee
which reported to US Congress on asteroid impact hazard. His research was
used by Hollywood in the films Armageddon and Deep Impact. But asteroid
strike was not Hollywood fiction, he said. The demise of the dinosaurs
was linked to the impact of a 10km asteroid in Mexico 65m years ago. In
1908, an asteroid about 100m across exploded 6km above the Earth, releasing
energy of a thousand Hiroshimas over Tunguska in Siberia.
-
- "An object coming in at 20km per second hitting
the atmosphere goes kerblam. It needs to be bigger than 100 metres in size
to reach the ground intact but that does not mean we are safe. Because
if the next Tunguska were to occur above Marble Arch in London, let us
say, the whole of London out to the M25 would be flattened," he said.
-
- The British government had taken no action on a report
from one of its own committees on asteroid hazard. But it paid to watch
the skies for asteroids: if spotted years, or better, decades early, they
could be averted. It would be delicate work.
-
- "Asteroids are piles of rubble held together by
their own gravity. You have to deal with them very gently," he said.
-
- A nuclear explosion detonated at the distance of a radius
- 500 metres in the case of a 1km asteroid - could slow or deflect the
monster even if it was due to collide in 20 years. There would be no blast
wave in space, but one side of the asteroid would be heated, and start
to vaporise. This would have a jetting effect, and could slow the monster
by half an inch a second.
-
- "It might not sound much, but half an inch over
20 years adds up to greater than the radius of the Earth. It would miss
us."
-
- But no matter how good the surveillance, no one will
get a chance to sound the alarm or deflect a chance vacuum fluctuation
before it happens. Matter is simply condensed energy, but that does not
explain why energy has no mass and matter does. So physicists believe that
particles move as if through an invisible jelly -called Higgs field - slowing
them down. Resistance to movement is a definition of mass. But this jelly
itself could change, quite randomly, in some distant part of the universe.
This would detonate a bubble of expanding destruction, Dr Allanach said.
It would change the laws of physics for the whole universe.
-
- "Light would stop shining, electricity would no
longer work and atoms would spontaneously break up. The universe that makes
us up, the Earth and the stars would disintegrate," he said. And this
bubble of death would expand at the speed of light, which meant no one
could know of its coming.
-
- But this event remained improbable, even over the lifetime
of a universe. It was roughly as probable as winning the lottery jackpot
twice on the same day -one in 13m squared.
-
- Space mass which fell to Earth -
-
- * There are more than 1m known asteroids, mostly in
the asteroid belt between Jupiter and Mars.
-
- * More than 1,000 asteroids with Earth-crossing orbits
have been spotted.
-
- * More that 100 tonnes of cosmic rubble hits the Earth
every day.
-
- * A 50 metre asteroid hits the Earth's atmosphere about
once a century, releasing the equivalent of 10 megatons of TNT in the explosion
-
- * A 1km asteroid - 500 are known - hits the Earth every
100,000 years. About 500 may remain undiscovered.
-
- * The largest asteroid ever identified on an Earth-crossing
orbit was spotted in July. It is 15-20km in size. It will pass the Earth
safely next April
-
- * Four teams in the US and one in Japan are watching
for new asteroids. Most tracking of known asteroids is done by amateur
astronomers.
-
- * There are no asteroid searchers in the southern hemisphere.
There is no funded Spaceguard programme in the UK.
-
- * There has been only one known victim of an object
from outer space in the last century - a dog in Egypt in 1912. Six people
may have been killed in the Tunguska event of 1908.
-
- http://education.guardian.co.uk/
|
