In 1996, scientists announced they had found evidence of ancient microbacterial life in a piece of meteorite that originated from Mars

In 1996, scientists announced they had found evidence of ancient microbacterial life in a piece of meteorite that originated from MarsPhoto: Nasa/Johnson Space Center

Written in a San Diego hotel coffee shop and dispatched to via an open wi-fi hub with lots of bandwidth.

Life on other planets is a tantalising prospect and a contentious issue that might soon be resolved.

Graffiti is often dismissed as worthless but I often find it humorous and subtle. Occasionally, it even conveys an interesting conjecture. One piece I saw said:
God is alive and well but working on a less ambitious project.

It made me smile and think, but others were not amused. To foster debate, I have raised this hypothesis with many groups over the years.

The reaction is bounded by two extreme views:

1. We are the ultimate creation of God and life only exists on this planet.
2. Life probably exists throughout the cosmos as a consequence of the laws of nature being the same everywhere.

Very occasionally a third view pops up which I really like:

3. If life isn’t omnipresent, we have a moral obligation to get out there and spread it around so it doesn’t die out in the future.

The debate always ranges widely, with a tendency to be heated. It often includes Seti, or the search for extraterrestrial intelligence, and our failure to find anyone, or anything, using radio. I often muse that we are probably looking in the wrong place, by the wrong mechanism, at the wrong time.

James Lovelock postulated methods by examining light spectra for detecting the right conditions for life as we know it on distant planets.

Carl Sagan pointed out the sheer abundance of stars and planets in the cosmos that allow for solar systems very similar to ours. While Frank Drake produced numeric estimates for the existence of life in the known universe.

Direct proof has been thin on the ground and subject to derision and suspicion. But slices of meteorites seem to be progressively changing scientific opinion. For me, the positive trail of evidence started in 1996 with the suspicion that a fragment of a Mars meteorite contained micro-biological elements. Needless to say, samples of this kind generated endless, and inconclusive, debate that continues today.

New evidence of extraterrestrial life

More recently, a new piece of evidence has turned up that looks rather more positive. Nasa astrobiologist Dr Richard Hoover Marshall thinks he has found conclusive evidence of alien life in the form of bacteria fossils in an extremely rare type of meteorite.

Interestingly, the extraterrestrial-life debate has become even more heated with people becoming even more strongly polarised for and against.

I see this debate as our scientific process hard at work, stacking up evidence for and against. But my guess is that we now know where to look and what to look for and we will see gathering evidence accumulating in the pro-camp.

The challenge for the anti-groups is to come up with non-biological processes that produce similar-looking specimens. That is the real value of the scientific method – to challenge and test until all reasonable doubt has been removed or at least the greatest weight of evidence lies on one side or the other.

Best of all paradigms

That approach is in stark contrast to all other paradigms that have failed to add any significant value to human progress and understanding.

When the last element of doubt is removed and all debate cools, we might then have the wisdom to make more general statements about life on different planets. But there remains a really enticing question to be pursued: is off-planet life in any way different to that found on-planet? If it were, it would really upset far more apple carts.

The likelihood is that carbon-based life using proteins, RNA and DNA is the only life deal going but it is not certain. Also, there is the prospect of non-carbon life.

These questions will either be answered by evidence from past lives off-planet or, perhaps more likely, in the future with new lives created in the lab on-planet.