New habitable planet discovered ?

[bojan]

Gliese 851g

http://www.wired.com/wiredscience/2010/09/real-habitable-exoplanet/

[En1gma]

So, when will sir Richard branson offer plane tickets??

[bojan]

As soon as he sorts out his computer system .

[renormalised]

Good one, Bojan:):)

This is a very interesting, and timely, discovery. Now it will mean that the hunt for habitable planets will kick on very quickly. They should also be looking at some of the closer stars as well for habitable planets.

[higginsdj]

Its a big step from finding a planet in the habitable zone to saying that they have discovered a habitable planet....... I think someone has made a huge assumption!

[renormalised]

Given everything being equal and the planet's physical characteristics, there's a fair chance that it is. But that still doesn't mean it is, for certain. It may not be and you are correct in saying it's an assumption. They need some direct observations of the planet to be able to confirm whether it is habitable or not.

[CraigS]

Very interesting ..

I agree .. good one Bojan !! Thanks !!
:):)

Ah .. but the diversity is a complicating issue .. I agree ..
:)
Cheers

[drsimmo]

Definitely agree there! It comes down to getting your story out there though. Which do you think a newspaper would pick up: "First habitable Earthlike planet found" or "Potentially barren rocky planet found"? ;)

[ngcles]

Hi Bojan & All,

This is a wonderful, wonderful feat of dedication and care to be able to compile such a massive dataset and analyse it. Kudos to the team ! :thumbsup:

One thing that is missing (and it has already been pointed out in the thread) from so many of the print and electronic media going around today is a very important word that is in both the original paper and the press release:

"potentially".

This body is "potentially habitable"

I point that out not to say it has or hasn't got people, advanced life, simple life or no life -- it may. It may not. All this paper and the press release has basically said that this is a planet reasonably similar in mass to the Earth, that may be assumed to have an approximately similar composition that is at the right distance from the parent star that if water is present, there may be portions of the planet were it could exist as a liquid. Liquid water is very, very important if not vital to life. So it is an important discovery as well as a great technical accomplishment by the team. There is no evidence that water is or isn't present, or an atmosphere, or what the atmosphere is like, or the surface. for that matter. Those facts may or many not be determined at a later time.

So I wouldn't be leaping to any further unwarranted or unsupported conclusions.

That's not to detract from the work by the team which is an incredible feat of persistence and technical know-how. Good on them !!

The original paper (I've only read the first few pages so far but it is reasonably easy going -- the abstract is written at almost popular level) is here:

http://www.ucolick.org/~vogt/ms_press-1.pdf


Best,

Les D

[marki]

Definately an interesting discovery but there are many unknowns for it to be called habitable eg does it have a liquid core and thus a magnetic field, been smacked by a huge rock in the last 5 billion years and lost it's atmosphere etc etc. The exciting thing is that they have found something in the right position and when you think of the trillions of stars out there.... there has to be something. Now how are we going to get there??? Mr Branson ......LOL

Mark

[renormalised]

Yep, Virgin Galactic are already selling tickets on the "Enterprise" for trips to there....I wonder what Kirk thinks about that. Hijacking his ship as a cruise liner:):P:P:P

[CraigS]

Carl's said it all .. but what I have difficulty with is wrapping my mind around the words underlined.

For example, in our Solar System .. at what point do we say Mars is habitable … as distinct from not habitable .. ? Short of astronauts setting up shop there for a couple of years .. and maybe (or not) surviving ?

Seems the probabilities will always drive the answer to the question.
(Mind you, Earth IS habitable - no probabilities in that statement).

:)

Cheers

[renormalised]

It all depends on the conditions present. Mars is habitable, to the extent that it is, because of what we've found there and assume we can use to make it habitable for a base/colony. Doesn't mean it will be easy or even possible in some cases. It means we can see all the resources we need are present and we may be able to exploit them to live there.

Is Earth so hospitable to life?? Think about it. Try and live in the Sahara with what you've got, now. You'd be lucky to last a few days, if that. Even worse in the Atacama Desert...some places there haven't seen rain in historical times...more than 400 years. There's plenty of places on this planet that aren't too great for living in.

[drsimmo]

In a technical sense though, Mars is NOT habitable. It is too far from the Sun for water to exist in liquid form under Earth-like conditions. Obviously, if you had a thicker and hotter atmosphere (ie a greenhouse effect) this would be a different story.

[renormalised]

Yes, you are right there...if you confine the definition of habitability as approximately Earth-like conditions. But if you were looking for the resources which would allow the planet to be made habitable under the conditions of an enclosed base, then everything is there. It's just a matter of their availability and how easily they can be extracted.

[mswhin63]

Although not to be taken as gospel http://en.wikipedia.org/wiki/Habitable_zone gives a brief explanation in current physics understanding of habital zone.

[renormalised]

HZ's are only a general concept...based on one example only....us. There could be many exceptions to the rule.

We extrapolate on the basis of the conditions found on Earth, but even here there are exceptions to the rule.

[higginsdj]

What 'fair chance'. All things being equal it is a remote possibility at best. What state is the planet in? Primordial and not a chnace of habitability. A dead rock and no magnetic field and the solar wind will have removed all trace of atmosphere. If it does have an atmosphere, of what does it comprise? What is the melaticity of the system? Did the inner solar system go through the same bombardment process as our own, the primary theory whereby habitable making material was delivered to our planet... Does the system have giant planets protecting the inner solar system?

As I said, what are you calling a 'fair chance'? Yes there is a possibility, but to lead the story saying a habitable planet has been found..... Note that I define 'habitable' as being something that our definition of life can inhabit.

Cheers

[renormalised]

I was just thinking...this is why we should be throwing money at figuring out how to develop FTL drive systems for ships. Start thinking outside the box as far as the physics goes. Try anything that might sound weird to present day physics and see what we come up with. Have a look at Heim's ideas and theory. Investigate the Finnish experiment and results further. Brainstorm....that's the only way we're going to do this.

These planets...whether they're gas giants or not, are far too close by and interesting to just let be and never bother to figure out how to get there!!!. If it takes 100 years, then so be it, but at least we could say we tried.

[Jay-qu]

No need to wait for FTL drives Renormalised, we just need to hit 1g sustained acceleration.

By my calculations, a trip to Gliese 581 (20light years) should take ~5 years (due to relativistic time dilation), though in Earth time it would be more like ~22 years. So a round trip, while only taking 10 years (+time to explore) will return you 44 years after you left..

[CraigS]

Interesting discussion … I'll be frank in saying that I'm not sure about it all myself ..

I mean, the Earth will get eaten up by the Sun (or collision with Andromeda, etc), so we have to find ways of leaving the place, eventually. So, we have to fund that exercise. Otherwise, following the "do nothing/don't spend" path logically results in us never escaping !

However, when you look at the unbelievable diversity of environments within our own Solar System planets/moons, it seems to me that the chances of finding another "goldilocks zone" are very slight. (Ie: extrapolating from our own earth-bound perspective, that is).

This then, is counter to the cosmological principal (http://en.wikipedia.org/wiki/Cosmological_principle). So, how can one make the quantum leap from our own Solar System observations/empircial evidence to the guiding Cosmological Principle without a little 'faith' ?

Now there's a real question for a Cosmologist/Astro Physicist!! :question:
:)

Cheers
PS: The 'zone' I'm referring to includes the variables needed to support life .. not just the locale.

[renormalised]

It's said "a probability of it being habitable"....not that it was.

It's in the right spot w.r.t. its orbit, so it has that potential.

You're being to narrow minded in your expectations of the system's characteristics. Some of your above assumptions are not necessarily correct. Case in point, Venus. No magnetic field, plenty of atmosphere despite the solar wind. Even in our own solar system, what we believe happened might not necessarily be the case. Giant planets aren't necessarily guardians of the inner solar system of any star. There are many instances where they do more harm than good, and they don't even have to migrate too far inwards to do damage. It was the jostling between Jupiter and Saturn which created the Late Heavy Bombardment and even now, they may not necessarily protect us from a strike. You have to be careful with interpreting the theory, because even the people studying it don't know all the answers.

The actual science behind the formation and subsequent evolution of planetary systems is far more complicated than you've outlined. I could go into it, as it's my speciality, but there's just not enough time (for my part) or space here to be discussing this topic in depth.

Here's the system at a glance....GL581 (http://en.wikipedia.org/wiki/Gliese_581)

[renormalised]

If you want to be able to explore the close by systems and not have to wait a human lifetime for anything to happen, you're going to have to forget about GR and glorified skyrockets as your means of travel.

Quite frankly, I don't want to have to rely on time dilation as a means of exploring the galaxy. That would be even more so for those left behind.

[renormalised]

Habitable zones are a feature of all stars, no matter how large they are. The most pressing factor which dominates above all other is just how long that zone remains habitable for and how wide it is. Smaller stars may have very long lifetimes, but there HZ's are smaller than larger stars. So, there's less chance of planets being in them, given all factors. Larger stars have wide HZ's, but they don't last as long. Also, so these zones migrate over time, as stars increases in luminosity as they age. Our own star's HZ is getting larger and further out as it ages....in about 1 billion years, this place will be uninhabitable as the Sun by then will be about 10% brighter than now. We are in the process of migrating out of the HZ of the Sun, due to it shifting outwards.The Earth will lose its water because of this. But even before then, the increasing luminosity will make living here much more difficult. For instance, in about 500 million years, C3 plants (those that photosynthesise 3 carbons to produce energy) will be becoming extinct, as the increasing luminosity of the Sun robs the atmosphere of CO2 (due to increasing oxydation) and the partial pressure drops below sustainable levels for these plants. C4 plants will last another 200-400 million years, but not much longer. After that, when the surface temp reaches an average of 50 degrees and there's no plants left, oxydation will begin to runaway and rob the atmosphere of the gas. With our oceans becoming water vapour, the temp will heat up (GH effect), more oxydation will occur, the water will breakup due to increasing temp and higher UV, but the CO2 in the rocks will by now be getting cooked out. Eventually, the Earth will end up like Venus is now...in about 2-2.5 billion years.

There will be goldilocks zones no matter where we go and they will be as common as the stars themselves, so there's an almost 100% certainty of finding one. Just what's there and what's happening is another question altogether.

[CraigS]

Sorry Carl;

I added the "PS" to my message whilst you were composing. Perhaps poor terminology, but I meant "zone" to include all the variables needed to generate and sustain life … not just the proximity to a Sun.

You have added the further dimension of age, though .. which would seem to make the chances lesser ?

Hmmm …

Cheers

[higginsdj]

Agreed, and thats my point. Seemingly based on location and size alone, people (those responsible for the article) have made some very big assumptions about habitability (perhaps on purpose to make a headline). There are a thousand more things as critical as these two factors, most of which we do not understand, that also need to be in place for habitability to be a reality.

All I am saying is that there is more probability that it is not habitable than the possibility that it is habitable because of the number of factors we don't know about the system.

Edit: My real gripe is sensationalism in reporting :)

Cheers

[renormalised]

Actually, age increases the chances...the longer the zone lasts for, the greater the chance of life sustaining conditions developing. You just need a planet present that has developed in the right manner. But we haven't yet even considered extreme cases of life and there are plenty of example even on this planet.

[renormalised]

And that's precisely why we need to directly observe this planet. Pity we can't go there at present. That'd solve the question once and for all:)

Got any crazy ideas we can throw a few billion dollars at??!!:):P

[CraigS]

In isolation, I tend to agree with David.

But when you consider the scale of the Universe, the small probability may be offset by the vast numbers of stars/planetary bodies.

However, perhaps life did occur … once …
:)
Cheers

[higginsdj]

We need a large space based interferometer....

[renormalised]

A couple of billion should get us a decent sized one:)

[higginsdj]

Yes, but of the billions of star systems with planets in the habitable zone, whats the chance that the first one we come across will be habitable? Beginners luck :)

[CraigS]

Probability = 1 …
… Planet = Earth

Cheers

[renormalised]

That's just it, nothing is or can be taken in isolation. Even if only 1/1000 stars had a planet orbiting in the habitable zone and 1/1000 of them were habitable, that would leave a very large number of habitable planets left to look at. That's just in this galaxy, alone.

[CraigS]

Probability = 1
Planet = Earth

[higginsdj]

Hmmmm, but would there be any habitable planets if we weren't here?

:)

[renormalised]

Not necessarily. If there are billions of them, even if 1/1000 of those is habitable, given the distribution of those planets about the galaxy being random, the chances of one being close by are actually very good.

[higginsdj]

Yes, but you are stating the odds 'favourably'. What if there were only 1/billion, then the odds are not so favourable! The 'odds' don't actually tell us much with such an empty pool to work from so to speak. ie we might be odds on to see one, but it may take 1000 goes before we do.

[renormalised]

Strong Anthropic Principle...the fact that we are here means there must be habitable planets, otherwise it would be a moot point. If we don't exist, neither do they.

Weak Anthropic Principle...the chances of a planet being habitable isn't necessarily a condition of our presence, but their observation by us means that fact is known and therefore they must exist, for we inhabit one of them.

Take you pick:)

[CraigS]

I reckon to assume life anywhere else requires a leap of faith.

Here's a reasonably reputable article (http://www.science20.com/news_releases/the_mathematical_probability_of_lif e_on_other_earth_like_planets) written by an (East Anglia) Professor.

Worth a quick a read .. it's not too long ..

Cheers

[renormalised]

Even if the odds were 1/10E9, given that they are randomly distributed, the chances of one being close by will still be quite favourable...maybe not more than a few percent, but that's better than no chance at all, or very little chance (0.001% or less).

In any case, the planet doesn't have to be any good for us to be habitable. The habitability entirely depends on what you define as being habitable, and by what is going to do the habitation.

What if it was like Pandora, in Avatar. That was essentially an Earth like planet, but some of the constituents of its atmosphere were poisonous to humans. It's water was also more alkaline than water on Earth. However, that wouldn't stop plants and such from evolving to meet those conditions and there are many plants here that can tolerate high alkalinity in the soils and water. Yet despite that, with the proper precautions and equipment, people lived quite well there (not counting angry natives:):P)

[renormalised]

Well, instead of arguing over semantics and opinions on theory, there's only one way this can be solved...get off our collective rears and go out there. Find it, pick it up in our hands....eat it even, if we have to. If we say it's too much to assume that life will be everywhere given all things being equal, then we also have to be fair and state the same about the opposite. It's too much to assume that life will only be confined to one little planet and that one planet only.

Even given what we do know, the chances of life just being here and nowhere else is so small it's not even worth considering as a chance.

[Alchemy]

Wow this thread took off..... We yearn to believe life is out there don't we...

From reading the original article, there was the assumption that a planet such as this would be tidally locked, therefore screaming hot one side frozen the other. With a supposedly habitable zone in between.... If this planet has an atmosphere and it moves around, it would freeze the water( assume it has some for a moment) on the cold side... So to our form of life its useless, id be curious to know what happens to the water vapor on the hot side??? Again useless to us, leaving supposedly "the habitable zone" to which air movement would move the water away, leaving I imagine a desert. Not much use to life either.

Just my quick musings, I could be wrong, feel free to agree or disagree, life as we know it.... And that's all we know for now, all needs liquid water to exist, I cant see liquid water existing on the surface, and that's where life first appeared here on earth .... So Houston we have a problem.

[ngcles]

Hi All,

I'd have to agree that while this particular planet holds a potential to be a habitable one, the probability is still fairly low that it would be a place that is capable of sustaining life of any sort, let alone multi-cellular life, let alone advanced life, let alone intelligent life. And for each one of those steps up the scale, you can "add" a 10^-2 or 10^-3 to the probability score.

However with the data from Kepler that will reduced and analysed over the coming several months, I think it is likely that far better prospects than this planet will be announced in the reasonably nearby future.

Getting a spectrum of this small world when it is no more than a few million km from its (by comparison) overpoweringly brilliant parent star to look for bio-markers in any possible atmosphere is fraught with technical problems that won't be solved very soon. Hopefully, over the next few months some more promising candidates will be announced that are more distant from their parent stars and will be less of a technical challenge (though still an extremely big ask) to obtain meaningful specta from.

I am perfectly prepared to have an open mind, but from what I've seen on the subject, I am still of the opinion that life is probably rare or even very rare in the galaxy, advanced life (like plants and animals) *extremely* rare at best and intelligent life (i.e self-aware, capable of making and using tools and manipulating the environment to their advantage) something like trillion-1 chance -- if not much worse.

Space-faring races I think are even rarer than that.

I'm perfectly happy to be proved wrong. If they land on the White-House lawn tomorrow, or send us an unambiguous proof of their existence I'd be perfectly happy to shake hands (pseudopodia etc) and say I was wrong. I just don't think it will happen.


Best,

Les D

[CraigS]

It is an interesting topic.

Another perspective is that without the vision of life elsewhere, or of a planet somewhere which is capable of sustaining life, there would be no reason to pursue it. Hence no reason to fund the chase.

The goal serves a purpose. Re-inforcing it, repeatedly, in the media serves that same purpose. Believing it appears to be optional, and is a matter of choice.

I for one, choose to support the goal.

The chase to achieve it makes it worthwhile.

The technologies & knowledge that will develop as a result, are likely to benefit everyone, which I view as the real justification.

Cheers

[xelasnave]

Every planet I have been to has life:rolleyes:...
It would be hard to accept there is no life anywhere but on Earth..
If we consider the Universe to be of only finite size ..and thats is about..80 billion light years across...Carl did mention the correct figure but its huge..and beyond human comprehension ....but what if an infinite universe then there must be life, one could reasonably think, other than only on this planet...in fact if infinite we each could be replicated to an infinitely...mmmm and the probability of life more grand than us could be so...
alex:):):)

[CraigS]

The converse is equally valid .. until life elsewhere is discovered.

There is only choice separating the two.
(IMHO).

Cheers
PS: G'Day Alex where ya been ? :)

[xelasnave]

I had a mate die and I have been helping his lady with the boat they just bought and were about to move onto the day he died... life is so short.
alex

[CraigS]

Sorry to hear that. Pass on my best wishes.

Cheers

[Ro84]

Anyway, it is also interesting to see if this planet - so close to its star - is or is not tidally locked, (I mean, if this planet shows ever the same face to its sun, as well as the Moon shows the same face to the Earth). This problem may be very common on planets too close to their stars, like Gliese 581c (in the same planetary system) and other planets around red stars that lie on habitable zone. If this is true, Gliese 581g may have a hemisphere in wich never is night and a hemisphere in wich never is day.

[mswhin63]

Being only 20 light years away it would be interesting if there is any intelligent radio-emissions from the planet. Seeing what we see is 20 years old worth a try.

[renormalised]

Well, here's the long and the short of GL581g (and related material) from a few better sources...

http://keckobservatory.org/news/keck_observatory_discovers_the_firs t_goldilocks_exoplanet/

http://arxiv.org/abs/1009.5733

http://www.sciencedirect.com.elibrary.jcu. edu.au/science?_ob=ArticleURL&_udi=B6WGF-45MFXSB-37&_user=972264&_coverDate=10%2F31%2F1997&_rdoc=14&_fmt=high&_orig=browse&_origin=browse&_zone=rslt_list_item&_srch=doc-info%28%23toc%236821%231997%2399870 9997%23306187%23FLP%23display%23Vol ume%29&_cdi=6821&_sort=d&_docanchor=&_ct=23&_acct=C000049659&_version=1&_urlVersion=0&_userid=972264&md5=38817f0e445f4f36811f23f8f267fe8 9&searchtype=a

http://arxiv.org/abs/astro-ph/0609799 (pick v1)

[renormalised]

They've already sent a signal there...remember they did, in 2008.

[higginsdj]

Just have to wait till 2028 to get a response :)

[renormalised]

Yep:)

"People of the planet Earth, you will now be assimilated into the Galactic Empire. Submit your government or governments to the will of the Emperor, or face immediate take over by the forces of the Imperial Army" <<<scratchy breathing noises...Imperial March playing in background>>>

:):P:P

[Ro84]

Lol

[CraigS]

…. Ah believe in exo-life .. I'm a believer !!
…. Take me to your leader !! ….

[drsimmo]

Or 2048 even... ;)

[drsimmo]

Some very interesting opinions and ideas in here.

I'm not quite sure where the notion that the probability of life on this planet is low though? Surely we don't know one way or the other? The key point is that this is the first planet to really be in the habitable zone of a star. That makes the probability that there is life a hell of a lot higher than any other planet we know of outside the Solar System.

[renormalised]

Precisely, Simon. Even if it is tidally locked, a planet in close orbit about an M class star (despite flares from some) can be eminently habitable.

We need starships:)

[astroron]

I have just read through this thread,some interesting ideas here,But would the habitable zone be quite small seeing as it is tidely locked to its
Star?

[renormalised]

The HZ of M class stars are small, regardless. The tidal locking of the planet has no bearing on this. That is just a characteristic of the planet w.r.t. its parent star.

[higginsdj]

Doh - of course....

[renormalised]

Here's some more articles (all much the same)...

http://www.newscientist.com/article/dn19519-found-first-rocky-exoplanet-that-could-host-life.html

http://news.ucsc.edu/2010/09/planet.html

http://carnegiescience.edu/news/potentially_habitable_planet_discov ered

[bojan]

I am guessing that the issue of HZ and locked rotation of the Gliese 581g was discussed from climatology and meteorology point of view as well.
It is quite conceivable for me that in this middle zone (between hot and cold hemispheres) there must be a lot of wind and generally the weather conditions there must be very unstable.
So perhaps the habitable area of such a planet is even smaller..

[renormalised]

Yes it was. Actually from the modeling that has been done on planets in this situation, despite the differences in temps between the two sides of the planet (if it's in fact tidally locked), the climates are far more stable than you might suppose. The atmospheres of the planets equilibrate fairly quickly and the temp differences become less pronounced, depending on how thick the atmosphere is. A planet of the size of this one will have a pretty substantial atmosphere...at least as thick as ours. I've included links about this in a previous post.

One thing that will be present, though, at the anti-solar point on the day side and that is a huge convection cell....cyclone, several thousand miles across, especially if it's covering an ocean.

However, the assumption of tidal locking was based on it's proximity to the parent star (over 13 million miles). But there's no guarantee that it is tidally locked....it's a large planet at a fair distance from a rather small star. Tidal locking depends on how the orbit of the planet, the rotation rates of the star and planet, the balance between the masses and the amount of flexure induced in the body of the planet by tidal influences has evolved over time. It might spin on its axis every 36 days, the same as its orbital period...we just don't know, yet.

[astroron]

Thanks for clearing that up in my mind Carl:)
Cheers

[renormalised]

Sure:)

[astroron]

Todays APOD
http://antwrp.gsfc.nasa.gov/apod/astropix.html
:thumbsup:

[renormalised]

I was wondering when they would have an APOD about this:). Thanks:)

[renormalised]

You know, I reckon they should start giving these planets proper names, instead of staying with rather bland designations. Like 51PegB...they wanted to call it Bellerophon, after the Greek hero, but the IAU said no.

What would they know...they stuffed up Pluto!!!:):P

One name has to be reserved though....Vulcan. That has to go to any habitable planet orbiting 40EriA (Beid). Even if it's not habitable and is just a lump of rock, can't go anywhere else:):P

[astroron]

One name has to be reserved though....Vulcan. That has to go to any habitable planet orbiting 40EriA (Beid). Even if it's not habitable and is just a lump of rock, can't go anywhere else:)http://www.iceinspace.com.au/forum/../vbiis/images/smilies/tongue05.gif
I hope they do, then you will definitely see all the Mr Spock jokes come out of the woodwork:)

[CraigS]

Vulcan got destroyed by 'Red Matter' in the last Star Trek ..
Does this mean that the name is now available for re-use ?

:)

Cheers

[renormalised]

Nope...they're chiseling a headstone for the gravesite as we speak:):P

[renormalised]

Spock might be waiting there even as we speak, for a lift back to Starfleet HQ:):P

[[1ponders]]

That won't happen for a few hundred years yet so dont start throwing it out yet ;)

[luigi]

I read at one of the many links about this that Vogt said something like "Give what we know about life and its ability to thrieve in all kinds of environments I'd say the probability of life in this planet is 100%"

I said "wow!" for the first time in many years a scientist is saying there must be life out there even if just hypothetical.

I hope to be around in 2048 when we get the reply
"please repeat message"

Now I need to write a sci-fi short story my plot is "In the year 2048 our message is anwsered... in French!"

[Robh]

I lie open to the possibility that life may eventually be found somewhere else in the Universe. However, we no nothing about the probability of a life event occurring.

The fact that there is life here on Earth says nothing about the probability of a life event on some planet in a far distance star system. We have no statistical data to make any conclusions. We don't really know how the first life forms popped into existence here on Earth. The existence of certain chemicals and perceived favourable conditions may not necessarily lead to a life event. The argument that there is an infinite number of stars and hence livable planets does not then lead to the conclusion that life must be quiet common. Consider. The set of integers is countably infinite, while the set of real numbers is uncountably infinite. Between any two integers there is an infinite number of real numbers. If it is required that the number of planets be more the size of the set of real numbers to ensure life on more than one planet in our known Universe but the number of planets is actually the size of the set of integers then we will have little luck in finding any other life out there.

Only by searching will we able to answer the question. Are we a lonely fluke of nature or is the Universe like a pristine rain forest, teeming with life?

Regards, Rob

[CraigS]

Real brain bender there, Rob. I agree with the logic and your conclusions which you've expressed via analogy, but can I ask what the difference between 'countable' and uncountable' is?

.. I mean if something is infinite, I don't see how it can be counted ?
Yet, this seems to be key to what you are saying.

Help me !

:)

Cheer & Rgds

[xelasnave]

I found a 48 cylinder motor bike on utube:eyepop:... yes 48...who would have thought such a thing was out there?

I bet the probability of someone building such a crazy thing as greater than the probability of life elsewhere.

We are happy to speculate upon the concept that matter is made up of little strings etc and yet many find it hard to speculate upon other life and more so life greater than us being found in other systems.

I suggest just because I did not have the imagination to build a 48 cylinder motor bike that they therefore could not exist.

In our solar system there is life on at least one planet does this not give us the probability rating for all other solar systems?
The problem is we only have one sample so we feel restricted to coming down on the unrealistic view we are somehow unique...

I suggest although we can only operate with one sample the pointer should be that in the sample we have we have at least one planet with life..until other samples contradict our only available sample that we can only conclude all samples will be the same and until other samples prove inconsistent to the current sample we are bound to attribute similar to all similar samples..or in other words..life should exist in the zones habitable by Earths standards...is it unreasonable to work on the basis that all samples will probably be different (no life) to the sample we observe ...

Would it not be arrogant in the extreme to approach the matter any other way for to do so suggests that we are somehow very very special indeed... we found we were not the center of the solar system was that not enough to cool human arrogance.


alex:):):)

[xelasnave]

Evidence re 48 cylinder bike can be found here

http://www.youtube.com/watch?v=9wQA49EZucg


alex

[Robh]

Countable in this sense means I can match every number in the set to a unique natural or counting number e.g. for the integers ... 0 is matched to 0, 1 to 1, -1 to 2, 2 to 3, -2 to 4 and so on. So the set of integers is effectively the same infinite size as the set of counting numbers. However, the set of real numbers is much larger than the set of counting numbers. No matter how I try to match each real number to a counting number, I can always invent another one that won't match. Example sqr(2) matched to 1, sqr(3) to 2, sqr(4) to 3 etc but then where does pi go?

Regards, Rob.

[renormalised]

In the oven:):P:P

[CraigS]

Thanks Rob.

You had me running away to read up on countable, uncountable, real and integers. I think I get it now. Learn something every day, huh ? Thanks for that.

Kind of challenges the definition of 'infinite', though .. I'm looking at this like the observable universe vs the real universe, which we think of as infinite.

It is difficult to articulate the huge statistical probabilities on all of this. As Alex mentioned 'samples' and 'sample sizes', it got me thinking as well.

I might get around to expressing myself more clearly on all this someday. It's not easy though .. I've had a couple of go's at it now and it very often comes out the wrong way.

:)

Cheers & Thanks.

[Robh]

That's the point, we have a sample of One. You cannot deduce any probabilities based on one planet. If life is that rare that we are the only planet with life on it within a billion light years distance, it will take us a long time to realise this.
I am not averse to the research. Who knows what we will find!

Regards, Rob

[renormalised]

You can't deduce anything with such a small sample, so anything you predicate on this is just a moot point. Nothing more than speculation. But that doesn't stop anyone from having an opinion, just that they have to be careful about how they word that opinion and how the come across with expressing it.

[CraigS]

This statement would seem to say that 'Habitable Zones' have nothing to do with finding life.

Conversely it could also be said that:

"If life is commonplace then it may not take us long to realise this".

So, the outcome is directly dependent on one's belief about whether life is commonplace or not.

Interesting, eh ?

Cheers

[Robh]

Wisely put.

Rob

[Robh]

These two statements are not equivalent.
Life exists here. Therefore it lives in a Habitable Zone.
This is a Habitable Zone. Therefore it must have life.

We have no evidence for the second statement.

Rob

[renormalised]

It's a case of habitable zones = chances of life = very good (but not a certainty)....I'd rate it at 90%. If the conditions for life, even as we know it are met, then chances are it's there. Look at our own planet....life got started here very early, before the LHB and even by then it was fairly advanced microbial life, so it was evolving even before then. It may have taken a long time to go beyond those stages, but that doesn't mean the same thing will happen elsewhere. Life might get off early on a planet and evolve much faster than here, or it may still be pea soup even after 5 billion years. Actually, the harsher the conditions, the more likely evolution will drive the appearance of advanced life forms earlier, so long as it's not overwhelmingly harsh. You could say diversity in adversity. Our little neck of the universe may have been a bit too cushy for life, for all we know.

[CraigS]

Cool.

Cheers

[Alchemy]

I watch with interest, most threads regarding the possibility of life, I think to humans curiosity is just the most natural thing.

Habitable zone really just refers to the temperature requirements of liquid water, not much else.

So many factors are required for our life to exist, an automatic assumption that life is there on this planet inferred or otherwise is awesomely optimistic, and really is just a headline grabber, nothing else.

Mars had water, for a long time too. It's not that far away, yet we can't determine with any accuracy does it/ did it have life. So clearly trying to determine such for a planet 20 light years away presents some difficulties.

[renormalised]

The only real way we're going to be able to tell is actually go there. Whether that's Mars or GL581g, or anywhere else for that matter.

[CraigS]

Yep .. the chase is worth the effort .. and will benefit everyone !!

Cheers

[Karls48]

And then when we get there the “life” on that that planet could be so different to ours that it will regard us as merely part of spacecraft systems. And it will determine that real intelligent life on board is the guidance computer. Unless it runs Microsoft operating system:P:

[renormalised]

In which case, they will put it in a home for the severely handicapped:):P

Seriously though, you have a very good point. Something that was brought up in the first Star Trek movie with the Enterprise's encounter with the entity V'ger. What if the planet was populated by living, sentient machines. They may not recognise carbon based lifeforms as being sentient, or even alive. Especially if they've never encountered that type of life before.

[renormalised]

If these guys knew anything about atmospheric physics, geology, stellar physics and evolution, they'd be a danger to themselves...most of the posts borders on driveling...but then again it is based on Thornhill's nonsense.

http://thunderbolts.info/forum/phpBB3/viewtopic.php?f=4&t=3758

What makes me laugh are the signatures of these fools...they're really not worth repeating and most read like "corn flakes packet" wisdom. But then again, something like that would be lost on these guys, considering how easily duped they are.

[xelasnave]

Also maybe what we consider to be habitable places an unnecessary restriction upon life as where we can expect to find it...maybe in other places is not so.
Consider the life around those underwater volcano vents ..should not happen but it has... life near those deep brine pools away from solar radiation.Only a few years ago any scientist worth feeding would have declared life was impossible due to the harsh conditions.

Also we can only think about carbon based life forms..perhaps there will be other forms of life beyond what we consider to be possible... I have heard speculation upon silicon life form ...

Even water may not be as critical as we estimate.

We have one sample..or one example upon which we can comment but the number of bodies in the universe as we suspect it to be would suggest so many opportunities even a one in a billion chance would see life almost "everywhere".

I think there is a message with the utube 48 cylinder bike... being beyond our expectations or imagination has little to do with the reality of somethings existence.

Also when one considers the variety of life forms on this planet it suggests a determination by life to be there irrespective of the wild adaptions to fit a particular environment. I do wonder if there will be only one DNA or will it just be peculiar to Earth. So interesting that all life on this planet has the same basic floor plan..that is so very curious and suggestive that such a plan would be able to adapt to any place at all.

I caught part of a conspiracy movie today (so stupid it hurt) but it suggests we will need an external threat (a nasty ET to replace the, by that time, the eliminated terrorists) and after humans have eliminated all violence on the planet..we will need outsiders from out there ..all based on the need of war for capitalism to survive etc...so in that context the powers will need to find life and make sure it is a threat to us...:rolleyes:
add to that the dictate of nature ..only the strong survive I feel we need to start the search in earnest;).

As our powers of observation become better we may be able to find hints in distant atmospheres that strongly suggest life... not so intelligent life should provide smog readings;)
Now the United Nations have a human selected to interact with the first being from beyond ...mmm they must know more than they let on:P
alex:):):)

[xelasnave]

I feel I can out drivel anyone at thunderbolts
alex

[renormalised]

Those were good points Alex. You are right....even now they're considering the possibility of methane based lifeforms on Titan, with methane replacing water as the solvent of choice. Like I mentioned earlier, the only way we'll ever really know and get to understand life in its fullest is to go to these places. What we will see and learn in the process is going to open up so much to us and in the process of getting there, we will discover and invent things that we can't even begin to dream of today. That's why we need to take that first step, now.

[renormalised]

I don't think so, Alex. They have driveling and dubious thought down to a very fine and specific art. Most are masters at it:):P

[Sylvain]

This is so true! Just imagining all that we could discover...it's just beyond imagination! I would love to live in such an era!!! Let's hope (foolishly?) that it is to happen in the years to come.
I always hope that one of our radio-telescope will catch some kind of signal...it could change everything!

Fascinating thread by the way, thanks everyone!

[snas]

Alex, I agree. Since we are now touching on my area (biology) I feel I am somewhat qualified to pass comment. All the talk of planets in the habitable zone, presence of water, oxygen, carbon etc is all very well if you are searching for Earth-like life. But, as we have seen on Earth life has been found to flourish in "uninhabitable" locations such as in the superheated, high pressure water around volcanic vents in deep ocean and even flourishing in pools of sulphurous "magma". The bacteria found near volcanic vents are called thermophiles (heat loving) and have been shown via their DNA to be related to all other life on Earth via the "single common ancestor".

So if life can survive in such places, who is to say that life has to occur only in certain places, on certain types of planets. It is possible that life may be possible on a wide variety of planets, either Earth or Jupiter sized, with an Earth like atmosphere or a Jovian etc etc etc like atmosphere, close to a sun-like star or farther away from a very different star.

However the current research on thermophiles indicates that they probably adapted to life in their current environments, rather than being the "original" life form themselves. If this is true, then maybe life is required to form on an Earth like planet before it can gradually evolve to life such as thermophiles.

Paul Davies (Arizona State University) has (or maybe by now that should be had??) a theory (or perhaps hypothesis would be more correct) that life on Earth developed and was wiped out on several occasions during the 'early period of heavy bombardment.

The suggestions that follow on from this is that, if life did form on Earth on several separate occasions then:

1. Life WILL form if it is at all possible for it do so.
and therefore
2. Life MUST exist elsewhere in the Universe.

Again, these are suggestions, but the point is that if something so apparently unlikely can happen several times over on one planet, then the drive for life to form from abiotic substrates would appear to be so strong as to make life almost a certainty. Or....would it???

The converse of this is that, if life did only form on Earth once, then maybe we truly are alone. :(

Or......are we? :shrug:

Stuart

[xelasnave]

Sometimes I like to indulge my imagination with things folk dismiss as impossible and on one of those times I imagined that there could be very very intelligent life on Mars... so intelligent that after years of technical and industrial development they realized to save themselves they had to take all the remaining water and atmosphere under the surface of the planet:eyepop:. so maybe such could be so..what the mind can conceive always has a chance at being a reality I like to think...and of course all life on Earth does similar in so far as it will adapt to the conditions available...now being surface dwellers we perhaps find such a prospect unreasonable. Anyways it would be funny if one of the Mars landers fell down a ventilation shaft and into a subterranean civilization more advanced than us.... mmm now would that not be a great movie plot.

I think the DNA thing is extraordinary and for me suggests that life will probably be everywhere in the universe...it is the universal floor plan and with it life can build whatever body it needs to fit certainly anything available on Earth and I suspect any place out there really...well maybe not the Sun but who knows for sure.

alex:):):)

[adman]

can I just back up a few paces here - how fast would you be going if you accelerated at 1g for 5 years (or is that 22 years?)? And how the hell do you slow yourself from this velocity to a safe landing velocity?

I think you might make a good projectile like the one that kicked up all that water on the moon! At least the resulting spray might give us some good data about the composition of the planet - although you would have to make allowances for the organic matter of the unlucky astronauts.....

Seriously though - there seems to be a lot of thought given to acheiving a high velocity to shorten the trip, but little consideration of how to stop at the other end. What are the options for slowing a spacecraft?

Adam

[snas]

Alex,

I think it's pretty fair to say that any compounds required for life are not going to do to well on or in the sun. :)

But then, ........

Regards
Stuart

[CraigS]

The existence of Gliese 581g is disputed !

Doubt cast on existence of habitable alien world (http://www.physorg.com/news/2010-10-habitable-alien-world.html)



The 'f' planet is disputed as well:



Have we been manipulated by the media, yet again ?

Cheers

[mswhin63]

Somewhat of a chance, but could be someone jumping the gun, getting all excited.

[drsimmo]

Tricky situation... one thing that is definitely true is that multi-planet systems are very hard to find and confirm. A fair bit more debate about these planets to come I suspect.

Also, a disclaimer: I collaborate with Paul Butler and Steve Vogt, but not on this particular system.