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Feature - The Sun is Dying and Global Dimming by Brian Cox

 

Two mini-features from the CERN physicist and scientific advisor to the movie Sunshine.

The Sun is Dying

The Sun will not live forever. It has enough fuel left, if our current understanding is correct, for another 5 billion years, at which point it will die. But could it be possible for the Sun to die much sooner, within the next 100 years even? From a scientific perspective, it should be said that this is very unlikely. But, it is also true that there is a lot about the universe that we do not understand.

Over the last few years astronomers have observed that there is extra "stuff" in the universe that we can see only by its gravitational influence on stars and galaxies. This stuff goes by the name of Dark Matter, and there is five times as much Dark Matter in the universe as there is normal matter, the stuff that makes up you, me, and the stars and planets we can see with our telescopes. What is this mysterious stuff? It's possible, some scientists would say likely even, that this stuff is made of particles known as supersymmetric particles, a new and exotic form of matter that is high on the list of potential discoveries at CERN's giant Large Hadron Collider, a 27km in circumference machine which begins operations this year after almost a decade of construction.

Theoretical physicists have spent many years calculating the properties of these supersymmetric particles, and we have a reasonable theoretical understanding of how they might behave. One possibility is that they could clump together into giant balls known as Q-balls. If this is true, then these heavy and exotic objects could have been made billionths of a second after our Universe began, and still be roaming the Universe today. It is speculated that, if a Q-ball drifts into the heart of a super-dense object such as a neutron star, it could begin to eat away at it's core like a cancer, until the star is no longer massive enough to maintain itself and explodes in a violent explosion. Such explosions, known as gamma ray bursts, are seen in the Universe, although their cause is as yet unknown.

Could such a dangerous, exotic object drift into the Sun's core and cause it to stop shining? It is likely that the Sun is many times too diffuse to stop a Q-ball - it would power right through. But maybe, just maybe, some strange exotic form of matter from the earliest times in the universe could settle deep within the Sun's core, and disrupt its function enough to cause the catastrophic scenario seen in Sunshine. It's far-fetched, but we have a saying in physics that anything that isn't explicitly ruled out is therefore possible, so in the final analysis, you never quite know.

Global Dimming 

It is now suspected that pollution in the Earth's atmosphere, caused by industrialization and natural phenomena such as volcanic eruptions, may have significantly reduced that amount of sunlight reaching the Earth's surface. It is estimated that this could have led to a cooling effect of over 1 degree overt he last 40 years, which would go some way to offsetting the effect of global warming. Global warming is caused primarily by increasing carbon dioxide levels in the atmosphere that prevent heat being radiated back out into space from the Earth's surface.

The phenomenon of global dimming may therefore have saved us, so far, from the worst affects of climate change, although it has been noticed that as pollution levels have been reduced, particularly in Western Europe, the affects of global dimming seem to be reducing, leading to an accelerating temperature rise once again. We may therefore be in the paradoxical situation that reducing pollution might INCREASE the effects of global warming, leading us ever more quickly towards catastrophe.

This discovery isn't all bad, however, because it may suggest a short term solution to climate change. Why not intentionally put pollutants, which may be designed to be benign in other respects, into the atmosphere to accelerate global dimming, and therefore slow the climate change caused by carbon dioxide emissions. Several suggestions along these lines have been made, including adding small particles to airplane fuel, and therefore using one of the main contributors to climate change, aircraft, to slow its effects. It's an intriguing possibility, and one that is the focus of significant research, although it should be said that we cannot at present predict the effects of such fine-tuning of the climate, so global dimming shouldn't be seen as a means to allow us to continue to increase carbon dioxide emissions.

Brian Cox is science advisor to the movie Sunshine - see www.sunshinemovie.co.uk

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Last update 05 June 2007