Doubts about hyped-up planet
Does Gliese 581g exist at all?
Zina Deretsky, National Science Foundation
The planetary orbits in the Gliese 581 system compared to those of our own solar
system. However, latest studies cast doubt on the existence of Gliese 581g.
By Shaun Doyle
Published: 24 November 2011(GMT+10)
Remember the claims of ET life on an extrasolar planet last year? Readers may recall
the outstanding claims and the hype, if only from
our article on the subject, in which one researcher was cited as being “100%”
sure that it had life on it.1
But it’s likely that not many have heard that the existence of Gliese 581g,
the planet where this ET life was so certain to exist, has now itself been called
into serious question.
A number of studies and re-analyses have been conducted since the ‘discovery’
of Gliese 581g that have cast significant doubt on Vogt et al.’s
interpretation of their data.
A Swiss team presented evidence that suggested Gliese 581g may not even exist.2 Despite finding that the probability
for the non-existence of Gliese 581g was small, statistically, the measurements
on which it was based were still not significantly different to the background noise
in those same measurements. This is enough to cast reasonable doubt on the existence
of Gliese 581g, at least for now. The major reason for this uncertainty is that
our current technology is at this point stretched to its limit looking for exoplanets
the purported size of Gliese 581g. Therefore the Swiss team came to the correct
conclusion based on their data. The existence of Gliese 581g will most likely only
be confirmed (or not) with more sensitive detection equipment.
A re-analysis of Vogt et al.’s data by using a complex form of statistics
called Bayesian inference also added further doubt to the original conclusions of
Vogt et al.3 This
study concluded that Gliese 581g had a 99.9978% chance of being a false positive
result based on the current data, thus the existence of Gliese 581g is highly doubtful
at the moment.
Far from being ‘100% certain’ that life exists on this alleged planet,
we don’t even know if Gliese 581g exists at all.
Nevertheless, Vogt and his fellow researchers stand by their data and remain unconvinced
that these studies have falsified their claims.4
A number of other studies have been written that either support5 or deny6
the existence of Gliese 581g.
So where does this leave us? At the moment, the debate about the existence of Gliese
581g seems to be at a stalemate. It seems that only new and higher resolution data
will be able to definitively solve the matter. But this is the nature of science:
tentative, open to revision based on new data, and open to reinterpretation using
different analytical techniques. It provides a sober warning about trusting hyped-up,
evolution-supporting claims in the media as soon as they break. There is no scientific
reason to suspect that anything other than Earth-based life exists in the universe.
So far from being ‘100% certain’ that life exists on this alleged planet,
we don’t even know if Gliese 581g exists at all.
A reader’s commentDaniel L., South Africa, 25 November 2011
It is not surprising that life will not be possible on Gliese 581g (if it exists). The video “Privileged Planet” [Link removed as per feedback rules—Ed.] made it very clear why. Keep up the good work! |
Related articles
Further reading
References
- Vogt, S.S., Butler, R.P., Rivera, E.J., et al., The
Lick-Carnegie Exoplanet Survey: A 3.1 M_Earth Planet in the Habitable Zone of the
Nearby M3V Star Gliese 581, Astrophysical Journal, (in press), 2010. www.arxiv.org/abs/1009.5733.
Return to text.
- Mullen, L., Doubt cast on existence of possibly habitable
alien planet, MSNBC.com, 12 October 2010. www.msnbc.msn.com/id/39640401/ns/technology_and_science-space/.
Return to text.
- Gregory P.C., Bayesian Re-analysis of the Gliese 581 Exoplanet
System. arXiv: 1101.0800, 5 January 2011. www.arxiv.org/abs/1101.0800. Return
to text.
- Osbourne, D., Goldilocks planet lost in translation, 14 January
2011, www.abc.net.au/science/articles/2011/01/14/3113180.htm; Plait, P., Does Gliese
581g exist? Discover, 18 January 2011. www.blogs.discovermagazine.com/badastronomy/2011/01/18/does-gliese-581g-exist/.
Return to text.
- E.g. Anglada-Escudé, G. and Dawson, R.I., Aliases of
the first eccentric harmonic : Is GJ 581g a genuine planet candidate? arXiv: 1011.0186,
29 April 2011. www.arxiv.org/abs/1011.0186. Return to text.
- E.g. Andrae, R., Schulze-Hartung, T. and Melchior, P., Dos
and don’ts of reduced chi-squared, arXiv: 1012.3754, 16 December 2010. arxiv.org/abs/1012.3754.
Return to text.
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