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Author Topic: There's no one out there!  (Read 57876 times)

dodgy geezer

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Re: There's no one out there!
« Reply #150 on: January 09, 2010, 11:21:39 AM »

Now for the bigger problem.

A dyson sphere of the type proposed here - a solid sphere which would intercept all radiation from a sun - suffers from several intractible issues. It would be subject to extreme mechanical stresses, beyond theoretical limits for known or theorised materials, and worse, would be orbitally unstable.

Dyson himself never proposed such a structure for these reasons. They are completely impractical, and only exist in fictional descriptions where their various fundamental problems can be ignored. There are therfore very good engineering problems which explain why the fictional type of dyson sphere will never actually be built, no matter how capable an alien civilisation gets at matter manipulation. Dyson's explanation is here:

http://www.sciencemag.org/cgi/content/citation/132/3421/252-a  (subscription required) It includes the quote:

"A solid shell or ring surrounding a star is mechanically impossible. The form of 'biosphere' which I envisaged consists of a loose collection or swarm of objects traveling on independent orbits around the star."


It therefore seems to me to be unreasonable to base a belief that there are no alien civilisations on an inability to detect a particular construction which can only exist in the imagination. Mayhemers may wish to note that Dysons actual proposals involved individual energy collectors orbiting suns, that a sufficient number of these would probably modify the star's output towards the infra-red, and that the SETI study is looking, amongst other things, for such signals. SETI is ongoing and regularly reports possible sightings of interest. If someone wants to find out how long this study has been progressing, what fraction of the sky has been covered and how many items of interest have been found, we may have the basis for a more balanced opinion....
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Jimmy James

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Re: There's no one out there!
« Reply #151 on: January 09, 2010, 12:34:26 PM »

Maybe the constrution of a dyson sphere is an electroinc field not solid matter (force field) in which case it might be undetectable to our present instruments???
 Freebooter :-) ok2 :-))
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polaris

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Re: There's no one out there!
« Reply #152 on: January 09, 2010, 06:41:17 PM »


Dear Dreadstar,

It is impossible really to say what you have said really, as we simply don't know what tech. might exist out there  O0(& the operative word of course is 'might'!).

As to Dyson Spheres, well all this/that is suppostion isn't it... but fiction has been proved right on a great many occasions! :-)

Magnetism is certainly a force to be recond with, and such is the route of force fields... just a 'matter' of being able to build and retain one to sufficient strength... that's all!!! :-) Per example knows the real meaning of magnetohydrodynamics for example........... and this is only the beginning.............. let alone magnetic levitation.... which we mere humans have only touched upon thus far......

Regards, Bernard
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PMK

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Re: There's no one out there!
« Reply #153 on: January 09, 2010, 09:53:54 PM »

.... which we mere humans have only touched upon thus far......
Regards, Bernard

Ah-ha! So in that case, Mr P, I put it to you that, by your very own implications and admissions, that you openly admit to believing that we mere humans are but of inferior knowledge to..... to some off-planet species?.......... what, what, what?!
Go on, admit it - you believe in aliens.
Me too.
I've never seen a real live whale in any of the oceans. But I believe they exist. Likewise, nor have I seen a chameloen in the jungle. But I believe they exist. I've never even seen an orchid. But I believe they exist.
They're all alien in that sense, so yep....

As for the other ones, the ones from space.... Yeah, we got one living round our way already.

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justboatonic

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Re: There's no one out there!
« Reply #154 on: January 09, 2010, 10:58:48 PM »

Now for the bigger problem.

A dyson sphere of the type proposed here - a solid sphere which would intercept all radiation from a sun - suffers from several intractible issues. It would be subject to extreme mechanical stresses, beyond theoretical limits for known or theorised materials, and worse, would be orbitally unstable.

Dyson himself never proposed such a structure for these reasons. They are completely impractical, and only exist in fictional descriptions where their various fundamental problems can be ignored. There are therfore very good engineering problems which explain why the fictional type of dyson sphere will never actually be built, no matter how capable an alien civilisation gets at matter manipulation. Dyson's explanation is here:

http://www.sciencemag.org/cgi/content/citation/132/3421/252-a  (subscription required) It includes the quote:

"A solid shell or ring surrounding a star is mechanically impossible. The form of 'biosphere' which I envisaged consists of a loose collection or swarm of objects traveling on independent orbits around the star."


It therefore seems to me to be unreasonable to base a belief that there are no alien civilisations on an inability to detect a particular construction which can only exist in the imagination. Mayhemers may wish to note that Dysons actual proposals involved individual energy collectors orbiting suns, that a sufficient number of these would probably modify the star's output towards the infra-red, and that the SETI study is looking, amongst other things, for such signals. SETI is ongoing and regularly reports possible sightings of interest. If someone wants to find out how long this study has been progressing, what fraction of the sky has been covered and how many items of interest have been found, we may have the basis for a more balanced opinion....


On the point of dreadstar first, you have to consider the type of civilisation that would be capable of building a dyson sphere. There is a scale to illustrate this which can be found anywhere on the net but the link here is to wikipedia http://en.wikipedia.org/wiki/Kardashev_scale

This scale, determines the potential 'advancement' of civilisations in a galaxy. The scale ranges from type 1 able to master the resources of the civilisation's home planet, type 2, mastering the resources of its solar system to type 3 mastering the resources of its galaxy. Incidentally, we are considered to be less than a type 1 civilisation since we cannot harness all our planet's resources. Clearly that being the case, we couldnt harness the entire resources in our solar system or galaxy to build a dyson sphere.

Regarding dyson spheres themselves, we could debate whether dyson envisaged completely enclosing a star or merely a collection of individual satellites to encompass the star. (Incidentally, Dyson did originally refer to this as a 'shell.'

Irrespective of whether the sphere was 'solid' or merely a massive collection of individual satellites to encompass the whole star, the structure would still be more massive than the parent star and hence would still sufficiently affect gravity and light to make them easily noticeable.

In any event, the concept of a solid 'edge' of a dyson sphere is still compatible with advanced thinking. The term dyson sphere could be considered the generic term for such a massive structure and should not be dismissed simply because dyson's original concept of such a structure may have been developed by other to reflect the more common held vision of a 'dyson speher' ie the total encompassment of a host star by a sufficiently advanced civilisation.

http://en.wikipedia.org/wiki/Dyson_sphere

A Dyson sphere is a hypothetical megastructure originally described by Freeman Dyson. Such a "sphere" would be a system of orbiting solar power satellites meant to completely encompass a star and capture most or all of its energy output. Dyson speculated that such structures would be the logical consequence of the long-term survival and escalating energy needs of a technological civilization, and proposed that searching for evidence of the existence of such structures might lead to the detection of advanced intelligent extraterrestrial life.

Since then, other variant designs involving building an artificial structure or a series of structures to encompass a star have been proposed in exploratory engineering or described in science fiction under the name "Dyson sphere". These later proposals have not been limited to solar power stations many involve habitation or industrial elements. Most fictional depictions describe a solid shell of matter enclosing a star (see diagram at right), which is considered the least plausible variant of the idea (see below).

Regarding SETI's search, in 40 years not one verified candidate signal has been found. Frank Drake stated recently that if no such signal is found within the next 25 years, we would need to give serious consideration to the question of whether we were alone. Frank Drake is famous for the Drake Equation which can be used to calculate how many intelligent civilisations there are in the galaxy. Frank Drake is also a founder of SETI.
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dodgy geezer

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Re: There's no one out there!
« Reply #155 on: January 09, 2010, 11:58:53 PM »


Regarding SETI's search, in 40 years not one verified candidate signal has been found. Frank Drake stated recently that if no such signal is found within the next 25 years, we would need to give serious consideration to the question of whether we were alone. Frank Drake is famous for the Drake Equation which can be used to calculate how many intelligent civilisations there are in the galaxy. Frank Drake is also a founder of SETI.


If Dr Drake shares your view that we are alone, he must have come to this conclusion quite recently. Here is part of an interview he held with Der Speigel on 12 June 2009:
 

" ONLINE: Mr. Drake, after searching for decades, no extraterrestrial signal has yet been found. Are we alone in the universe?

Drake: We are definitely not alone. At the same time, I think it will be very hard to find the extraterrestrials. If they are only slightly more advanced than we are, they may be using technologies that don't reveal them. Not because they are trying to hide themselves, but because of the fact that every evidence that we find of extraterrestrials has to come from some form of energy that is wasted. If they are clever, they will be using technologies that do not waste energy."

http://www.spiegel.de/international/world/0,1518,629411,00.html



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cbr900

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Re: There's no one out there!
« Reply #156 on: January 10, 2010, 11:04:12 AM »

PMK,

Mate you need to get out more mate, that list you haven't seen
I have seen all in the last twelve months, get out and explore it is
really worth it......... :-)) :-))


Roy
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justboatonic

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Re: There's no one out there!
« Reply #157 on: January 10, 2010, 06:00:21 PM »

If Dr Drake shares your view that we are alone, he must have come to this conclusion quite recently. Here is part of an interview he held with Der Speigel on 12 June 2009:
 

" ONLINE: Mr. Drake, after searching for decades, no extraterrestrial signal has yet been found. Are we alone in the universe?

Drake: We are definitely not alone. At the same time, I think it will be very hard to find the extraterrestrials. If they are only slightly more advanced than we are, they may be using technologies that don't reveal them. Not because they are trying to hide themselves, but because of the fact that every evidence that we find of extraterrestrials has to come from some form of energy that is wasted. If they are clever, they will be using technologies that do not waste energy."

http://www.spiegel.de/international/world/0,1518,629411,00.html





DG, I think you are deliberately misreading my posts. I have not said Frank Drake has changed his mind about a SETI signal. I said Frank Drake recently stated in an article that if a SETI signal had not been received within the next 25 years then (at that point) Drake suggested we would need to consider in the absence of such a signal, that we are alone. Unfortunately I cannot find the said article. However, the essence of what Drake is saying is this, in 25 years time, SETI would have been searching for nearly 70 years. Each year has seen increasing more sensitive equipment being used and millions of radio frequencies listened to, by such equipment.

The Allen Array would probably be bigger than it is now, We'd have refined our earth size planet hunting by Kepler and potentially other missions. SETI is as you point out, also looking for artificial light signals from an intelligent civilisation.

By the end of the kepler mission, we should have a very good idea how common 'our' type of solar system is. I contend the evidence we have so far, based on 400 exoplanets found todate, that the informations points to our solar system is not the norm. Nearly every exo system found to date has hot jupiters. While this doesnt preclude the formation of earth type planets in the habitable zone, it does in all the simulations run result in earth size planets being ejected from that solar system.

If all these searches are pointing to the same conclusion their is no other technologically advanced civilisation then, we are probably alone. At the beginning of this thread, my post mentioned Fermie's Paradox, the Rare Earth Hypothesis, Von Nuemann Probes and Bracewell Probes. I have also mentioned dyson spheres.

You simply cannot say a reasoning that we are alone or, possibly the most technologically advanced civilisation in the galaxy right now is based on a single premise. What Im saying is the evidence is mounting. Fermie's Paradox, if the galaxy is teeming with life, where is it? No radio or light signals detected. No evidence of VN or Bracewell probes, no evidence of dyson spheres, no solar system yet found that is not of the hot jupiter model, the Rare Earth Hypothesis which, argues even if there are millions of Sun like stars in the galaxy, the likelihood of another earth forming around it and developing an intelligent civilisation within the same time frame as us is questionable.

My premise is, although there may have been past intelligent civilisations in the galaxy and may well be after we are gone, the probability is that we are the only intelligent civilisation in the galaxy right now.
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dodgy geezer

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Re: There's no one out there!
« Reply #158 on: January 10, 2010, 09:11:29 PM »


... Nearly every exo system found to date has hot jupiters. ...... What Im saying is the evidence is mounting.....
 
My premise is, although there may have been past intelligent civilisations in the galaxy and may well be after we are gone, the probability is that we are the only intelligent civilisation in the galaxy right now.

Now this is the point at which I disagree. We are looking for evidence with ever-increasing sophistication.

Our early investigations really had little or no hope of finding anything. We are now just getting to the stage where we will be possibly be able to find earth-like planets, so long as all the conditions are right. Finding one will take about 3 years with Keppler.

To get to that stage, we passed through the stage of being able to find large gas giants close to their suns - hot jupiters. So of course we have found a good few of those. But the fact that we have found lots of hot jupiters does NOT mean they are more common than earths (though they may well be). It just means that our equipment can find these much more easily. We can find several hot jupiters in 6 weeks with Keppler.

So although we MAY be alone, I don't think you can say the evidence is mounting. That is misreading the evidence. We EXPECTED to find lots of gas giants first - we didn't expect that we would find an equal number of both kinds of planet with this equipment. All we can say is that the experiment is proceeding as expected...
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Jimmy James

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Re: There's no one out there!
« Reply #159 on: January 10, 2010, 10:42:53 PM »

I think you are all barking up the wrong tree... You are looking for people like us ... or developed tecnology like ours ... I think this is tunnel vision ... just because we use radio waves why do they have to ... why do they have to live on earth like worlds ... why couldn't a race live on a world that to us would be deadly, as for Com's we can't talk to whales or dolphins but we know that they have a language which we are just starting to realise is more complected than our own... I think that to use our yard stick(Metre stick For the younger ones) is more than a bit short sighted ... and to think that we on this one little planet (which is right off the beaten track out near the end of an arm in our Galaxie which sort of makes us country bumkins ) is the only one with intelligent life in the whole universe is one of the sillest statements ever made ...How many billions of star's are there and how many of them have planets... Anyway who said that intelligence has to grow on a planet???

I'll Put my soap box away now
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kiwi

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Re: There's no one out there!
« Reply #160 on: January 10, 2010, 11:59:21 PM »

Well said.
Have to agree
kiwi
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justboatonic

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Re: There's no one out there!
« Reply #161 on: January 11, 2010, 12:03:59 PM »

Now this is the point at which I disagree. We are looking for evidence with ever-increasing sophistication.

Our early investigations really had little or no hope of finding anything. We are now just getting to the stage where we will be possibly be able to find earth-like planets, so long as all the conditions are right. Finding one will take about 3 years with Keppler.

To get to that stage, we passed through the stage of being able to find large gas giants close to their suns - hot jupiters. So of course we have found a good few of those. But the fact that we have found lots of hot jupiters does NOT mean they are more common than earths (though they may well be). It just means that our equipment can find these much more easily. We can find several hot jupiters in 6 weeks with Keppler.

So although we MAY be alone, I don't think you can say the evidence is mounting. That is misreading the evidence. We EXPECTED to find lots of gas giants first - we didn't expect that we would find an equal number of both kinds of planet with this equipment. All we can say is that the experiment is proceeding as expected...

With respect DG, I dont understand how you can really disagree with the evidence from the number of and type of exo solar systems found so far. 400 exoplanets found so far and virtually every one of these a hot jupiter ie large gasseous planets which orbit so close to their parent stars that their year is measured in upto 10 - 15  of our days.

Also, these hot jupiters have been found with our current technology. When we start getting results from kepler, we may (hopefully) start seeing earth type planets but and this is an important point, the number of hot jupiters will also continue to be found by kepler in every larger numbers. Kepler will not only find earth size planets if they are there, it will also find more hot jupiters. More hot jupiter systems lessens the chances of earth size planets in the habitable zone.

There seems to be an assumption that kepler will exclude hot jupiters to look for earth size planets. It wont. The data on hot jupiters will still be found by kepler. The only thing is kepler is also sensitive enough to 'see' earth size planets if they are there.

In any event, all this ignores occams razor. The simplest explanation tends to be the best one.
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malcolmfrary

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Re: There's no one out there!
« Reply #162 on: January 11, 2010, 12:22:17 PM »

Very true - Kepler gives a better view of everything, the huge percentage that can't carry life as we know it, and the probably diminishing percentage that can with a bit of luck.  The problems are that those than could possibly, might well be beyond any range that we could contemplate contacting and getting an answer within our lifespan.  Any reply would be received by someone a few generations along the line, assuming that there was the will to listen, or look.
I have still to see a totally convincing explanation as to why we have a collection of gas giants way out there, and a small collection of rocky planets within their orbit that were not absorbed by either the Sun or the gas giants while they were forming, and as long as there are several explanations, there is the probability that they are all wrong.

Anyway, this Occam's razor, how many blades?
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dreadnought72

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Re: There's no one out there!
« Reply #163 on: January 11, 2010, 02:22:35 PM »

With respect DG, I dont understand how you can really disagree with the evidence from the number of and type of exo solar systems found so far. 400 exoplanets found so far and virtually every one of these a hot jupiter ie large gasseous planets which orbit so close to their parent stars that their year is measured in upto 10 - 15  of our days.

But that's meaningless in the wider scheme of things. It is simply a selection pressure. What's one of those? Well, if I stand outside Ibrox on a particular Saturday, I might be led to believe that most people on Earth wear blue. Clearly this is not the case - I've just read the data wrongly - or, rather, extrapolated a result from incomplete data.

Spotting hot Jupiters occurs simply because that's the only type of system that the current methods can detect. It doesn't mean that "most", "a few" or "almost all" extrasolar systems are like this - we just haven't enough data to put a figure on the rareness or otherwise of "our" type of system.

And that's why Kepler's so exciting - we're now just a few years away from some real figures for the proportions and types of extrasolar systems. First time in human history. I think that's quite exciting.  :-))

Andy
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dodgy geezer

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Re: There's no one out there!
« Reply #164 on: January 11, 2010, 03:31:02 PM »


 It is simply a selection pressure. What's one of those? Well, if I stand outside Ibrox on a particular Saturday, I might be led to believe that most people on Earth wear blue. Clearly this is not the case - I've just read the data wrongly - or, rather, extrapolated a result from incomplete data.


Dreadnought72 has accurately described my point.

Actually, it's a little more complicated, as we believe that Keppler is capable of seeing Earth-type planets just as easily as Hot Jupiters. The differential is not necessarily because there are more HJs than Es (though that may be true). The differential is because we are looking for dimming as a planet crosses the face of its sun.

For an E type planet orbiting at 1Au, we will have to wait an average of 6 months for the first crossing to occur, by definition. For an HJ orbiting at 0.1Au or less, the transit period may be 10 days. Some have been discovered with a period of less than a day. Now, one crossing is not enough - that could be dimming for any reason - you need to obtain a regular predictable variation before you can say there is something orbiting that star. That is why three years is a sensible minimum for a planet taking 1 year to orbit, while a week or two may be fine to confirm an HJ.

Then on top of this issue you have to apply a correction for the angle at which you are viewing the system - a big planet at 0.1 Au is much more likely to coincide with our viewing angle than a small planet 10 times further out. I have not got the time to compute an estimate, but I would guess the difference could be several orders of magnitude?

We have just got the first 6 weeks data from Keppler. It is not surprising to find it containing some HJs. It might contain loads of initial Es, but it CANNOT contain any verified Es, by definition - the soonest we can have those will be in 1 year.

So I cannot see that the evidence for few or no Earths is 'mounting'. Our detection process for them is designed to take a minimum 2-3 years, and to throw up many more HJs in the process. There may indeed be few or no Earths out there, but you just cannot take the number of putative HJs found so far and say that this is evidence for few Es. That is a misunderstanding of the theory of the detection process.
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Jimmy James

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Re: There's no one out there!
« Reply #165 on: January 11, 2010, 08:01:47 PM »

Well said.. In fact I think 2-3 years is no way near long enough, as when we are looking at another star the angle is so fine that to see the shadow or flicker of a planet passing between us and the star must be Millions to one at the distances we are talking about ... In fact if the plane of rotation is more than a degree or two out you might never see it...
Jimmy
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dodgy geezer

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Re: There's no one out there!
« Reply #166 on: January 11, 2010, 08:18:24 PM »

.... the angle is so fine that to see the shadow or flicker of a planet passing between us and the star must be Millions to one at the distances we are talking about ... In fact if the plane of rotation is more than a degree or two out you might never see it...

Exactly. Though there are lots of stars, so in fact you do get lucky sometimes. However, HJs are fatter and, crucially, closer, so you will see them at a much greater angle than you will see an E-type.

With Keppler we have a chance of seeing some e-types. But because of the way you are looking, you should not be surprised to find a lot of HJs first....
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Wasyl

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Re: There's no one out there!
« Reply #167 on: January 12, 2010, 12:27:02 AM »

I,ll just stick to what i know best,..dyson = hoover and E-Type = Jaguar,as for all you Astronomer Extraordinaries, and budding physicists,just get back to boat building,as all this gobbledy gook is giving me a headache,and a good old chuckle as well, {-) {-) {-)

Wullie
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dodgy geezer

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Re: There's no one out there!
« Reply #168 on: January 12, 2010, 09:57:40 AM »

...as for all you Astronomer Extraordinaries, and budding physicists,

Budding? All my blossoms fell off ages ago!
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Bryan Young

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Re: There's no one out there!
« Reply #169 on: January 12, 2010, 07:15:15 PM »

All this talk about "Kepler". He was a German,right? Now the question...was there or was there not a "Keppler" (2 "Ps") who was an Englishman? The "Kepler" that is constantly referred to on this thread seems to me to be somewhat divorced from the "Keppler" whose laws of Interplanetry Motion seem to hold good.
Goes something like this:......The speed of an orbiting body about a point in an eliptical orbit will encompass the same area of the elipse no matter how long the orbit, in the time taken to orbit. Speed and motion really, but clever trigonometry has proved he was correct.
Same guy or not? BY.
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dodgy geezer

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Re: There's no one out there!
« Reply #170 on: January 12, 2010, 09:55:20 PM »

All this talk about "Kepler". He was a German,right? Now the question...was there or was there not a "Keppler" (2 "Ps") who was an Englishman? The "Kepler" that is constantly referred to on this thread seems to me to be somewhat divorced from the "Keppler" whose laws of Interplanetry Motion seem to hold good.
...

OK - My bad - can't spell - can't model - can dance a bit......
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Jimmy James

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Re: There's no one out there!
« Reply #171 on: January 18, 2010, 08:50:09 PM »

Please Mister
I think I saw a little green once ...He was mounted on a pink El-E FANT... and I saw him ride through the messdeck and down the starboard allyway... T-was on my 21st birthday when I got sippers from half the division, Gulpers from Guns and a pinker from the Jimmy T-was a good day that, Must of been because I can't remember how it finished Hic!!!
Freebooter
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justboatonic

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Re: There's no one out there!
« Reply #172 on: January 18, 2010, 10:51:06 PM »

But that's meaningless in the wider scheme of things. It is simply a selection pressure. What's one of those? Well, if I stand outside Ibrox on a particular Saturday, I might be led to believe that most people on Earth wear blue. Clearly this is not the case - I've just read the data wrongly - or, rather, extrapolated a result from incomplete data.

Spotting hot Jupiters occurs simply because that's the only type of system that the current methods can detect. It doesn't mean that "most", "a few" or "almost all" extrasolar systems are like this - we just haven't enough data to put a figure on the rareness or otherwise of "our" type of system.

And that's why Kepler's so exciting - we're now just a few years away from some real figures for the proportions and types of extrasolar systems. First time in human history. I think that's quite exciting.  :-))

Andy

Sorry but that's plain wrong. Keppler (I really dont see what missing a p has to do with anything here but Ive corrected it all the same!) will find more hot jupiters but it is also sensitive enough to find earth size planets if they are out there. What you are neglecting to take account of is that the vast majority of exoplanets found to date are hot jupiters which orbit very close to their parent star. This means they have migrated inwards from an orbit as far out or more than jupiter is in our system or, they formed very close to their parent star in the first place.

If the hot jupiter formed close to its parent star, then the likelihood is that no earth size planet could form in that system since it would 'hoover up' all the dust etc needed to form an earth size planet in the habitable zone.

If the hot jupiter migrated inwards to its current orbit from further out, this does not necessarily preclude the formation of earth sized planets in the habitable zone but does, in all simulations todate, end up with the hot jupiter ejecting the earth size planet from that system. These are the findings of the people who say hot jupiters do not prevent earth size planets forming.

What this indicates to us is that in an exosystem that has a hot jupiter in it, it is so far unlikely that an earth size planet will be able to exist in that system long enough to give multicellular life chance to exist.

The only exosystem found to date with out a hot jupiter in it and being a little like our own is the Glize system However, Glize is a brown drawf and one of its planets is in the habitable zone although this planet is estimated to be at least twice the mass of earth. So now we have a planet in a habitable zone but its at least twice the size of Earth and around a brown dwarf. The averages dont look good.

Keppler has the ability to find exo earths but will they be in the habitable zone? It will also find more hot jupiters as it has already demonstrated.

In 3 years time we may have more idea to confirm just how rare the earth is.
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sheerline

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Re: There's no one out there!
« Reply #173 on: January 19, 2010, 12:02:00 AM »

Wasyl, we've got a Sebo upright, brilliant cleaner, German of course..... loads of suckin force!  :-))
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dodgy geezer

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Re: There's no one out there!
« Reply #174 on: January 19, 2010, 01:41:18 AM »


What you are neglecting to take account of is that the vast majority of exoplanets found to date are hot jupiters which orbit very close to their parent star.....  The averages dont look good.


Let us put a few hypothetical figures down to illustrate the points.

It is comparatively easy to detect a big planet close to a sun. In this position it occludes the sun well, and causes the maximum gravitational wobble. Our telescope systems have scanned many star systems and found a few planetary systems - mainly HJs.

Now we have a new, more powerful system, which may pick up habitable zone earths. It will take 3 years to do so, for reasons I explained earlier. But it can detect HJs much faster, in the order of a week or so.

We have pointed it at, let us say, 100 systems. Out of these, we confirm 10 HJs. It is possible that there are 50 habitable Es in the data as well, but we won't know for 2-3 years.

We have confirmed the HJs, so we announce them. They get added to the pile of already-detected HJs, so it looks like we are only detecting HJs. But this is because:

- our early detection could only detect HJs (being simplistic)
- our current detection will detect HJs first

If you knew how many systems had been scanned to detect the 10 HJs, you could make some comment about possible earths. For instance, if only 10 systems had been scanned, and all had an HJ, it would be reasonable to say that habitable Es look as if they might be rare, since we assume a habitable E cannot co-exist with an HJ. But I do not know this figure. Do you? Because it is important for your argument, and you seem to have left it out....

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