Our unlikely solar system

Apr 11, 2011 By Steve Nerlich, Universe Today
A circumstellar disk of debris around a matured stellar system may indicate that Earth-like planets lie within - since such a disk results from the collisional grinding of rocky planetesimals. Credit: NASA.

Recent modeling of solar mass stars with planetary systems, found that a system with four rocky planets and four gas giants in stable orbits – and only a sparsely populated outer belt of planetesimals – has only a 15 to 25% likelihood of developing. While you might be skeptical about the validity of a model that puts our best known planetary system in the unlikely basket, there may be some truth in this finding.

This modeling has been informed by the current database of known exoplanets and otherwise based on some prima facie reasonable assumptions. Firstly, it is assumed that are unable to form within the frost line of a system – a line beyond which hydrogen compounds, like water, methane and ammonia would exist as ice. For our Solar System, this line is about 2.7 astronomical units from the Sun – which is roughly in the middle of the asteroid belt.

Gas giants are thought to only be able to form this far out as their formation requires a large volume of solid material (in the form of ices) which then become the cores of the gas giants. While there may be just as much rocky material like iron, nickel and silicon outside the frost line, these materials are not abundant enough to play a significant role in forming giant planets and any planetesimals they may form are either gobbled up by the giants or flung out of orbit.

The Moon has retained a comprehensive record of the Late Heavy Bombardment from 4.1 to 3.8 billion years ago - resulting from a reconfiguration of the gas giants. As well as clearing out much of debris disk of the early Solar System, this reconfiguration flung material into the inner solar system to bombard the rocky planets.

However, within the frost line, rocky materials are the dominant basis for planet forming – since most light gas is blown out of the region by force of the stellar wind and other light compounds (such as H2O and CO2) are only sustained by accretion within forming planetesimals of heavier materials (such as iron, nickel and silicates). Appreciably-sized would probably form in these regions within 10-100 million years after the star’s birth.

So, perhaps a little parochially, it is assumed that you start with a system of three regions – an inner terrestrial planet forming region, a gas giant forming region and an outer region of unbound planetesimals, where the star’s gravity is not sufficient to draw material in to engage in further accretion.

From this base, Raymond et al ran a set of 152 variations, from which a number of broad rules emerged. Firstly, it seems that the likelihood of sustaining terrestrial inner planets is very dependent on the stability of the gas giants’ orbits. Frequently, gravitational perturbations amongst the gas giants results in them adopting more eccentric elliptical orbits which then clears out all the – or sends them crashing into the star. Only 40% of systems retained more than one terrestrial planet, 20% had just one and 40% had lost them all.

Debris disks of hot and cold dust were found to be common phenomena in matured systems which did retain terrestrial planets. In all systems, primal dust is largely cleared out within the first few hundred million years – by radiation or by planets. But, where terrestrial planets are retained, there is a replenishment of this dust – presumably via collisional grinding of rocky planetesimals.

This finding is reflected in the paper’s title Debris disks as signposts of terrestrial planet formation. If this modeling work is an accurate reflection of reality, then debris disks are common in systems with stable gas giants – and hence persisting terrestrial planets – but are absent from systems with highly eccentric gas giant orbits, where the terrestrial planets have been cleared out.

Nonetheless, the Solar System appears as unusual in this schema. It is proposed that perturbations within our gas giants’ orbits, leading to the Late Heavy Bombardment, were indeed late with respect to how other systems usually behave. This has left us with an unusually high number of terrestrial planets which had formed before the gas giant reconfiguration began. And the lateness of the event, after all the collisions which built the terrestrial planets were finished, cleared out most of the debris disk that might have been there – apart from that faint hint of Zodiacal light that you might notice in a dark sky after sunset or before dawn.

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User comments : 116

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CapitalismPrevails
2.2 / 5 (12) Apr 11, 2011
Maybe we are "Unique".
CHollman82
4.5 / 5 (8) Apr 11, 2011
So... 60% of systems should have terrestrial planets?

That's not exactly rare.
Quantum_Conundrum
1.8 / 5 (25) Apr 11, 2011
So... 60% of systems should have terrestrial planets?

That's not exactly rare.


I think what you should take from this is:

1, there aren't billions of stars out there with 3 or more terrestrial planets.

2, the fewer planets a star has, the less likely one or more of them would be in the habitable zone.

3) Earth really is unique
CHollman82
4 / 5 (22) Apr 11, 2011
So... 60% of systems should have terrestrial planets?

That's not exactly rare.


I think what you should take from this is:

1, there aren't billions of stars out there with 3 or more terrestrial planets.

2, the fewer planets a star has, the less likely one or more of them would be in the habitable zone.

3) Earth really is unique


I think you're full of shit... I think if anyone took any of those things away from this they would be a fool. I think your driving motive in everything you post is to propogate your religious nonsense.

There certainly are billions of planets out there, probably trillions. Whether or not Earth is unique is dependent on what traits you consider important. Earth is probably unique in the most basic sense, in that I doubt there is an exact replica of it somewhere, where I am typing the same thing I am now...
Temple
5 / 5 (8) Apr 11, 2011
"Recent modeling has shown."

Fa! Kepler laughs at your flawed models with its experimental evidence.

Here's a little article I wrote on the Kepler mission and how it is changing our view of the cosmos:

A Plethora of Planets:
http://www.isthis...planets/

I'm already stunned by the first batches of data released by the Kepler team. Over the next couple years, we're going to be flabbergasted with the science that that team is doing.
J-n
5 / 5 (16) Apr 11, 2011
1, there aren't billions of stars out there with 3 or more terrestrial planets.


While usually you're really into the math on stuff, this one you dropped the ball.

There are between 10 sextillion (10000000000000000000000) and 1 septillion stars in the Universe (Very rough estimate, we will use the very low number of 1 sextillion (1000000000000000000000) stars), which means even if only 1 in a million stars have 3 or more planets this leaves us with 1 quadrillion stars with 3 or more planets.

That's if only 1 out of every Million stars has 3 planets or more... and this study said that 40% of all stars have 1 or more planet, that's 400 quintillion (400000000000000000000) stars (if there is only 1 sextillion)with one or more planets.

Your numbers are off by a few orders of magnitude.
Modernmystic
1.2 / 5 (15) Apr 11, 2011
1, there aren't billions of stars out there with 3 or more terrestrial planets.


While usually you're really into the math on stuff, this one you dropped the ball.

There are between 10 sextillion (10000000000000000000000) and 1 septillion stars in the Universe (Very rough estimate, we will use the very low number of 1 sextillion (1000000000000000000000) stars), which means even if only 1 in a million stars have 3 or more planets this leaves us with 1 quadrillion stars with 3 or more planets.

That's if only 1 out of every Million stars has 3 planets or more... and this study said that 40% of all stars have 1 or more planet, that's 400 quintillion (400000000000000000000) stars (if there is only 1 sextillion)with one or more planets.

Your numbers are off by a few orders of magnitude.


So...where's ET then?....
J-n
2.4 / 5 (7) Apr 11, 2011
Probability suggests that ET is out there. Where is up to greater minds to dissect.
Modernmystic
1.4 / 5 (18) Apr 11, 2011
Probability suggests that ET is out there. Where is up to greater minds to dissect.


*cough* cop-out *cough*
Quantum_Conundrum
1.2 / 5 (18) Apr 11, 2011
Probability suggests that ET is out there. Where is up to greater minds to dissect.


I was speaking galactically, as travel between galaxies is almost certainly impossible, unless you have some sort of Star Trek style Warp field drive or a perpetual energy machine, as even anti-matter is not enough to accelerate a ship fast enough and to supply life support long enough to reach even Andromeda, even theoretically, even if you had like 99% efficient machines.

If there were intelligent space aliens living anywhere near us in the galaxy we would have already detected it, certainly if they were more advanced than us and had, say, a multi-system communications relay network or other things I have previously discussed.

Even if their communications were encrypted and operating on some exotic bandwidth, we would have detected it.

Excluding ridiculous things like macroscopic teleportation, time travel, and warp drives, we would have detected anyone relatively "close".
Quantum_Conundrum
1.4 / 5 (11) Apr 11, 2011
Ok, there is "one" theoretical way to make an intergalactic ship that can keep a civilization alive long enough to fly to another galaxy, but that would require making a stellar engine (which is essentially using the star's own power to push itself,) which requires the technology to make a TRUE Dyson Sphere.

Even then, it would take perhaps ten million years or so to reach a nearby galaxy and match speed.

So we can go ahead and exclude inter-galactic civilizations as being completely beyond possibility.

For example, we would know if anyone had such a stellar engine, because we would detect the star moving at relativistic or nearly relativistic speeds...
Temple
4.8 / 5 (16) Apr 11, 2011
If there were intelligent space aliens living anywhere near us in the galaxy we would have already detected it, certainly if they were more advanced than us and had, say, a multi-system communications relay network or other things I have previously discussed.

Even if their communications were encrypted and operating on some exotic bandwidth, we would have detected it.


So many assumptions implied as fact.
Au-Pu
4.6 / 5 (10) Apr 11, 2011
These researchers gave a planetary system of 4 rocky planets and 4 gas giants in stable orbits with a sparsely populated belt of planetesimals a 15% to 25% probability of development.
That would mean that the potential number of similar systems is enormous. We don't need to see how many zero's we can put to such a number. All we need to accept is that at even 5% or 10% which is much lower than their projections our system will not be unique.
As far as communication or contact is concerned we know the constraints that we face, so it would be reasonable to assume that "others" would face similar constraints.
Whether those constraints can be overcome is something we are trying to discover.
There could be billions of species out there all asking the same questions, Are we alone? Are there other species out there? Can we contact them? Are they trying to contact us?
Can we travel to find them?
Au-Pu
1.3 / 5 (6) Apr 11, 2011
An interesting footnote to the above.
The FBI has created a new resource called The Vault.
This contains thousands of FBI files that the FBI has made available.
Among them is a memo from a Guy Hottel who was the agent in charge of the Washington field office in 1950.
The memo's subject line is "Flying Saucers"
In this memo Hottel says an Air Force investigator stated that "three so-called flying saucers had been recovered in New Mexico"
Such an official memo raises a lot of questions.
It is probably time Governments became more open and honest with the people who put them there and whom they represent.
If this is true perhaps some of the questions in the previous posting could be answered.
FrankHerbert
4.6 / 5 (9) Apr 11, 2011
Okay I take back my post in another article about Q_C having a decent grasp of physics.
Moebius
1 / 5 (1) Apr 11, 2011
This is exactly the kind of theory that has no current way to be proven and is found to be wrong when it finally can be checked.
Moebius
4 / 5 (5) Apr 11, 2011
Ok, there is "one" theoretical way to make an intergalactic ship that can keep a civilization alive long enough to fly to another galaxy, but that would require making a stellar engine (which is essentially using the star's own power to push itself,) which requires the technology to make a TRUE Dyson Sphere.

Even then, it would take perhaps ten million years or so to reach a nearby galaxy and match speed.

So we can go ahead and exclude inter-galactic civilizations as being completely beyond possibility.

For example, we would know if anyone had such a stellar engine, because we would detect the star moving at relativistic or nearly relativistic speeds...


A Dyson sphere essentially makes that star system invisible.
malapropism
5 / 5 (1) Apr 12, 2011
A Dyson sphere essentially makes that star system invisible.

Would it be visible in infrared? (I'd have thought that the main energy problem with a full Dyson sphere would be to get rid of the waste heat. I guess if the star in question was moving at or near relativistic speed the red would be shifted according to the observer's reference frame but even then wouldn't it still be visible at some frequency?)
DamienS
5 / 5 (3) Apr 12, 2011
Would it be visible in infrared? I'd have thought that the main energy problem with a full Dyson sphere would be to get rid of the waste heat.

Yes, it probably would be visible in IR if the signature isn't swamped by other radiative sources. It also depends on how efficient the energy scavenging is inside the Dyson sphere as to how much would be wasted.
I guess if the star in question was moving at or near relativistic speed the red would be shifted according to the observer's reference frame

I don't think you would find too many stars traveling through space at anywhere near relativistic speeds. Even stars ejected by BHs from their galaxies don't do that.
Ethelred
3.4 / 5 (5) Apr 12, 2011
A Dyson sphere essentially makes that star system invisible.
No. A Dyson sphere is only invisible to the eye and we are not limited to the eye. Dyson sphere's radiate in the infra red AND if the thing is being used as a generation ship the drive would be visible, at least if it is pointed in our direction.

Ethelred
Ethelred
3 / 5 (4) Apr 12, 2011
(I'd have thought that the main energy problem with a full Dyson sphere would be to get rid of the waste heat.
In David Brin's last Uplift War book he had a modified Dyson Sphere because it turns out that they have problem with waste heat. They need some really serious radiators to dump the heat if they are to have a high energy capture rate.

Ethelred
Ethelred
4.2 / 5 (10) Apr 12, 2011
So...where's ET then?....
I suspect that there aren't very many. The article has rather a lot of terrestial planets but that includes Mars and Venus in our system. Life seems probable since it started so early here but inteligent life seems to have be a matter of luck.

Many systems would have a low metal content and thus life would be rare due to the lack of complexity that metal adds to the mix. Even if a planet should have life it took a long time for it to become multicellular.

Some species had to be the first with technoligical civilization. Perhaps it was us. Perhaps most can't be bothered with leaving their own system. It is going to be VERY hard for us to do so unless we can find a way to do it that we don't know about yet.

More
MarkyMark
not rated yet Apr 12, 2011
.
If there were intelligent space aliens living anywhere near us in the galaxy we would have already detected it, certainly if they were more advanced than us and had, say, a multi-system communications relay network or other things I have previously discussed.

Even if their communications were encrypted and operating on some exotic bandwidth, we would have detected it.

Excluding ridiculous things like macroscopic teleportation, time travel, and warp drives, we would have detected anyone relatively "close".

A lot of big assumptions here. You are assuming that advanced civilisations using methods we are familuar with, to put it simply just because we havent discovered some exotic tech such as say long range comms using quantum entanglement doesant mean to say some other lifeform hasant either. Also why do you assume all other alien cultures even use radiowaves. For all we know some other com method is more common its just that for whatever reason we have not discovered it.
Ethelred
3 / 5 (4) Apr 12, 2011
Charly Stross has been discussing this on site off and on for a while now. I think he is planning to write a book with star colinization based on what we know how to do now or can concieve of doing in the near future.

http://www.antipo...is-.html

That is a discussion about the SpaceX's Falcon Heavy.

Ethelred
Bog_Mire
3 / 5 (2) Apr 12, 2011
Probability suggests that ET is out there. Where is up to greater minds to dissect.


*cough* cop-out *cough*


has to be the wankiest comment in a while.
Up there with QC's 3rd comment on this article.
You infer that for ET to exist we must have had contact with it. What basal stupidity.
malapropism
3.7 / 5 (3) Apr 12, 2011
So...where's ET then?....
I suspect that there aren't very many... inteligent life seems to have be a matter of luck.

Some species had to be the first with technoligical civilization. Perhaps it was us. Perhaps most can't be bothered with leaving their own system. It is going to be VERY hard for us to do so unless we can find a way to do it that we don't know about yet.

As a speculative exercise, if we posit that the first epoch of stars were insufficiently complex to have metallic/rocky planets associated with them as seems indicated by scientific findings so far, then the 1st, say, 6Bn years (roughly half) of the universe's existence can be discounted as being conducive to life generation.

It took about 4Bn years for life on earth to develop to us, so there hasn't been all that much more time (2-3Bn years) for more advanced technological civilisations to develop. So I also tend to think there aren't many and they've probably been well dispersed in time and space.
Soylent_Grin
not rated yet Apr 12, 2011
For those who think this means Earth is unique...

Even with a 25% chance of a Sol like system forming, that still means a vast number of Sol like systems out there. "Vast" still applies even if we bring that percentage down to fractional numbers.

For those that are incredulous at how "perfect" Earth is for the existence of life, why would it be surprising to find life on a planet that has such favorable conditions?
Remember, 100% of planets you could find yourself on will have parameters similar to this one. 100% isn't "long odds", it's a sure thing.

If you're looking for support for the existence of a supernatural or miraculous origin of life, let's see us thrive where conditions *aren't* right for life. Stop looking at the possible and likely for God, and look at the impossible; that's what a miracle is, right?
yyz
5 / 5 (2) Apr 12, 2011
"Would [Dyson spheres] be visible in infrared?"

Richard Carrigan(Fermilab) has been a notable proponent of searches (mainly in the IR) for Dyson spheres and has conducted several himself using archival data from the IRAS satellite: http://iopscience...2075.pdf

He also maintains a webpage devoted to searches for Dyson spheres (there have been several, besides his own) with links to relevant papers: http://home.fnal....ches.htm

So far, only a few candidate objects have been found, and as noted, even these are ambiguous. Still, new, deeper IR surveys have recently come online (eg. GLIMPSE, WISE) and more are planned. While this might seem like a long shot to some, I don't see much of a downside to searches like this (and the cost is little or nothing using publicly available data).
Quantum_Conundrum
1 / 5 (1) Apr 12, 2011
A Dyson sphere essentially makes that star system invisible.


Not if you are using it to provide thrust.

In addition, dyson spheres do not absorb all energy, and even if they did, they would re-emitt energy in the Infrared spectrum, as another poster said.

No matter how much energy you absorb, and no matter how efficient your machines are, eventually the heat waste will escape as IR radiation, which will be detected and determined to be a dyson sphere via the emission lines.

In fact, "excess infrared" from a star system is one of the markers for a Type 2 or type 3 civilization.

The point of a stellar engine is that you can theoretically use the radiation and ejection from a star to move that star, thus having a nuclear reactor which will last for eons, long enough to perhaps move between adjacent galaxies during the lifetime of the host star...

Use Wikipedia and search for "Shkadov Thruster".
d_robison
5 / 5 (2) Apr 12, 2011
"This modeling has been informed by the current database of known exoplanets and otherwise based on some prima facie reasonable assumptions."

Essentially we are trying to model solar system formation with about 500 data points, and our limited knowledge of planetary system formation. Its a great place to begin, but unfortunately there are too many variables that we are unsure of, and too few observed planetary systems.

"Even with a 25% chance of a Sol like system forming, that still means a vast number of Sol like systems out there. "Vast" still applies even if we bring that percentage down to fractional numbers."

I'm certainly not flaming you, but remember models are just tools. The predictions of models, especially in this case, are not necessarily fact.

Now, back to the article, we would all love to put a number to how common or uncommon our planet and solar system are, but there is just not enough data.
Simonsez
not rated yet Apr 12, 2011
It seems everyone commenting so far on ET life has just assumed that intelligent life can only exist as a carbon-based lifeform restricted to the same physical limitations as humans/mammals. I suppose it's easier to think in those terms, but there is no such restriction on life. One thing is for certain regarding spacefaring alien life - they must have a method of FTL communication for colonies to exist outside of their immediate region and/or for their ships to "ping" planets for habitability/mining/etc.
Kingsix
not rated yet Apr 12, 2011
Dyson sphere

Wow, first it was the Dyson cyclone vacuum, then the Dyson ball, then the Dyson Blade hand dryer, now a Dyson sphere! What the heck will Patrick Dyson think of next? Ha

Seriously though, I think that it wouldn't be possible to say we are unique, but that life out there may be less possible than previously thought, but more so that it is probably spread out to extreme distances (even in stellar terms).

Either way its about time that we get our butts in gear and get out there, perfect off world structures, start figuring out how to terraform, and take this galaxy as our own.
d_robison
not rated yet Apr 12, 2011
It seems everyone commenting so far on ET life has just assumed that intelligent life can only exist as a carbon-based lifeform restricted to the same physical limitations as humans/mammals. I suppose it's easier to think in those terms, but there is no such restriction on life. One thing is for certain regarding spacefaring alien life - they must have a method of FTL communication for colonies to exist outside of their immediate region and/or for their ships to "ping" planets for habitability/mining/etc.

The reason we speculate that life is probably carbon based is for good reason:
1. Every data point we have for life is carbon-based.
2. Carbon is a fairly unique element in the way that it is able to bond with Hydrogen, Oxygen, and Nitrogen. One of the most prominent alternatives would be silicon-based life, however, these compounds usually take the form of a crystal-lattice structure rather than long chains, and are extremely stable which would not allow for permutations.etc
knikiy
not rated yet Apr 12, 2011

For example, we would know if anyone had such a stellar engine, because we would detect the star moving at relativistic or nearly relativistic speeds...


http://www.popsci...r-galaxy

sortof like this?
ShotmanMaslo
5 / 5 (3) Apr 12, 2011
Another possible way of travelling for advanced civilizations: upload your mind into a computer, and send the data at the speed of light to your destination. After arrival, your mind can run either on ordinary biological hardware again, or in silico.
Modernmystic
1.8 / 5 (5) Apr 12, 2011
Probability suggests that ET is out there. Where is up to greater minds to dissect.


*cough* cop-out *cough*


has to be the wankiest comment in a while.
Up there with QC's 3rd comment on this article.
You infer that for ET to exist we must have had contact with it. What basal stupidity.


All one has to do is look up the fermi-paradox and cut and paste an argument. It was and is a cop out.

Neither did I infer that for a civilization to exist we must have contact with them. I did infer that if there are a large number of them we would likely have some evidence by now.

Way to knock down that strawman though.

Eth, I suspect you're correct, there are ETs out there but I think they're few and far between.

There have been population I stars around long enough that if intelligence were at all common we'd see evidence of it everywhere...we don't.
Au-Pu
3.3 / 5 (4) Apr 12, 2011
Too many of the postings on this subject are little more than the biased views of the poster. Some fancy themselves as scientists and seek to argue the principles, whilst others are more general.
The major problem is we as a species are incredibly egocentric. This egocentricity causes us to see everything as if we were the sole example of everything. Our big bang/big crunch is an anthropomorphic view of the entire cosmos.
When we speak of alien life forms we don't have to go far to find them. We need only visit the mid ocean ridges in our own seas. There we find thriving communities that could not exist on or near the surface because those environments would be toxic to them, just as we could not live in their environments as they are toxic to us.
Therefore to slavishly contend that for life to exist it requires an Earth like planet is ridiculous.
We do not even know if any environment is more conducive than others for intelligent and technological civilisations to evolve.
DamienS
5 / 5 (2) Apr 13, 2011
The major problem is we as a species are incredibly egocentric.

I would say every species is egocentric, that is, concerned with self interests, individually and collectively. But I don't see how this view invalidates modern astrophysical observations & research.
This egocentricity causes us to see everything as if we were the sole example of everything.

We are the sole example of life in the universe so far. That's not being egocentric, it is simply fact. OTOH, we see and catalog other stars and star systems, galaxies, etc, which again has nothing to do with egocentrism.
Our big bang/big crunch is an anthropomorphic view of the entire cosmos.

How do you figure? Is it not down to observations?
DamienS
5 / 5 (4) Apr 13, 2011
When we speak of alien life forms we don't have to go far to find them. We need only visit the mid ocean ridges in our own seas

Almost by definition, anything found on Earth is not alien life. Different, yes, but still made from the same stuff. Some are searching for a 'shadow' biosphere, but nothing so far.
Therefore to slavishly contend that for life to exist it requires an Earth like planet is ridiculous.

I don't think anyone is 'slavishly' contending that. Scientists are just going by what we know from our sample of one, knowledge of elements, chemistry and physics, to make educated guesses. You can speculate about life on a neutron star, but how would you even recognize such life?
We do not even know if any environment is more conducive than others for intelligent and technological civilisations to evolve

We also have educated guesses there too, which absolutely doesn't mean that we think we know it all. We know we don't.
Beard
3 / 5 (2) Apr 13, 2011
The likelihood of simple life evolving, and of sapient life evolving are unknown variables at this time. We have a sample size of one.
CHollman82
3.7 / 5 (3) Apr 13, 2011
Our big bang/big crunch is an anthropomorphic view of the entire cosmos.


I'd be interested to see if you could support this... it seems untenable.
Modernmystic
1 / 5 (2) Apr 13, 2011
It seems everyone commenting so far on ET life has just assumed that intelligent life can only exist as a carbon-based lifeform restricted to the same physical limitations as humans/mammals. I suppose it's easier to think in those terms, but there is no such restriction on life. One thing is for certain regarding spacefaring alien life - they must have a method of FTL communication for colonies to exist outside of their immediate region and/or for their ships to "ping" planets for habitability/mining/etc.


We don't see any evidence of silicon (insert your favorite unsubstantiated element here) based intelligent life either. We don't see any evidence of ANY kind of intelligent life. YOU are the one making assumptions when you say it need not resemble us. How do you know? I'm not saying I disagree, but it's an assumption that's just as unfounded as any you're complaining about.

Oh and it only takes a few million years to colonize a galaxy WITHOUT FTL...
CHollman82
3 / 5 (2) Apr 13, 2011
We don't see any evidence of silicon (insert your favorite unsubstantiated element here) based intelligent life either. We don't see any evidence of ANY kind of intelligent life. YOU are the one making assumptions when you say it need not resemble us. How do you know? I'm not saying I disagree, but it's an assumption that's just as unfounded as any you're complaining about.


Let me introduce you to my friend Null Hypothesis:
http://en.wikiped...pothesis

or, if it better suits you:
http://simple.wik...pothesis
Modernmystic
1 / 5 (2) Apr 13, 2011
The likelihood of simple life evolving, and of sapient life evolving are unknown variables at this time. We have a sample size of one.


Technically true. However if you're one of the ones saying the universe should have a plethora of intelligent life or life bearing planets...then by your own argument our sample size is large but unknown. Whatever size it is, it isn't one.
CHollman82
3.7 / 5 (3) Apr 13, 2011
The likelihood of simple life evolving, and of sapient life evolving are unknown variables at this time. We have a sample size of one.


Technically true. However if you're one of the ones saying the universe should have a plethora of intelligent life or life bearing planets...then by your own argument our sample size is large but unknown. Whatever size it is, it isn't one.


You're confused...

The sample size of life bearing planets is one. The sample size of known planets is several hundred last I checked.

The set of known planets ~= The set of known life bearing planets. The set of known life bearing planets is a subset of the set of known planets.
Modernmystic
1 / 5 (2) Apr 13, 2011
The likelihood of simple life evolving, and of sapient life evolving are unknown variables at this time. We have a sample size of one.


Technically true. However if you're one of the ones saying the universe should have a plethora of intelligent life or life bearing planets...then by your own argument our sample size is large but unknown. Whatever size it is, it isn't one.


You're confused...

The sample size of life bearing planets is one. The sample size of known planets is several hundred last I checked.

The set of known planets ~= The set of known life bearing planets. The set of known life bearing planets is a subset of the set of known planets.


Well WHICH is it? You can't have your cake and eat it.

Either it is very likely that there is intelligent life out there and other planes like Earth litter the stars or it's not. If it is then we can ASSUME the sample size isn't one.

If not then my position is reasonable.

Now which is it?
CHollman82
3 / 5 (2) Apr 13, 2011
Which is exactly what I was saying, should I introduce you to my friend "reading comprehension"?


No it wasn't. The null hypothesis is that life can exist in unknown forms... Consider your statement in light of this understanding of the null hypothesis and get back to me.
Modernmystic
1 / 5 (3) Apr 13, 2011
No it wasn't. The null hypothesis is that life can exist in unknown forms... Consider your statement in light of this understanding of the null hypothesis and get back to me.


I agreed with him on that point. Either you CAN'T read or you only read what you want.
CHollman82
3 / 5 (2) Apr 13, 2011
No it wasn't. The null hypothesis is that life can exist in unknown forms... Consider your statement in light of this understanding of the null hypothesis and get back to me.


I agreed with him on that point. Either you CAN'T read or you only read what you want.


What was your point then, that the null hypothesis is an assumption?

Thanks for the valuable insight, I guess...
Modernmystic
1 / 5 (3) Apr 13, 2011

What was your point then, that the null hypothesis is an assumption?

Thanks for the valuable insight, I guess...


Indeed it was my point, he was complaining about people making assumptions, I pointed out his hypocrisy.

And you're welcome.

P.S. See this is the problem of butting into a conversation thinking that YOU have some valuable insight and not actually reading what was written. Are you in your twenties still? If so don't worry time will cure you of this malady.
CHollman82
3.7 / 5 (3) Apr 13, 2011
Indeed it was my point, he was complaining about people making assumptions, I pointed out his hypocrisy.

And you're welcome.

P.S. See this is the problem of butting into a conversation thinking that YOU have some valuable insight and not actually reading what was written. Are you in your twenties still? If so don't worry time will cure you of this malady.


Hint:
You referred to the notion that life may exist in unknown forms as an "unfounded assumption"

A null hypothesis is not an unfounded assumption... it is a "founded" assumption.
Modernmystic
1 / 5 (1) Apr 13, 2011
So is your assumption that there are many Earth-like planets and a lot of life in the universe founded or unfounded?
CHollman82
1 / 5 (1) Apr 13, 2011
So is your assumption that there are many Earth-like planets and a lot of life in the universe founded or unfounded?


Those are two assumptions, and only one of them is my own.

The assumption that there are many earth like planets is closer to founded than it is to unfounded. We know for a fact that there are an unimaginably large quantity of stars, and we have evidence that natural star formation processes lead to planet formation through accretion. This leads us to believe that there is likely a large star to planet ratio. Given that "earth-like" is not fully qualified I can't make any statements about the likelihood of any of these planets meeting those undefined criteria, I'm also not sure why it's particularly important aside from the fact that the specific form of life we know began on earth (even though much of it could live on other planets in this solar system if transported there)
FrankHerbert
1 / 5 (1) Apr 13, 2011
Nice ad homs modernmystic. Your arguments would still be shit without them though.
Modernmystic
1 / 5 (1) Apr 13, 2011
Nice ad homs modernmystic. Your arguments would still be shit without them though.


Coming from you, who rarely make arguments and instead just throw feces all over the "wall" that means...well...less than nothing...
Modernmystic
1 / 5 (1) Apr 13, 2011
The assumption that there are many earth like planets is closer to founded than it is to unfounded.


Oh, now there are degrees of "foundedness"...*snicker*

...This leads us to believe that there is likely a large star to planet ratio... I'm also not sure why it's particularly important aside from the fact that the specific form of life we know began on earth (even though much of it could live on other planets in this solar system if transported there)


Then my assumption that intelligence is rare seems founded then being based on the assumption that it's highly likely that our sample is far greater than one. especially since according to your "founded assumption" one doesn't need any Earth like planets as a prerequisite.

Again you can't have it both ways, as such win my argument no matter which assumption you use or lend more credence to.

I'm working on a cure for cancer and I haven't found it, is it reasonable for me to assume my sample for "success" 1
CHollman82
3 / 5 (2) Apr 13, 2011
Oh, now there are degrees of "foundedness"...*snicker*


There are degrees to everything...

Then my assumption that intelligence is rare seems founded then being based on the assumption that it's highly likely that our sample is far greater than one.


Define rare... I would tentatively agree with you that intelligence is rare but before I commit fully you must define what you mean by rare.

The size of our sample of planets which do or do not have intelligent life is arguable, but I would think that anywhere from 1 to 9 is a reasonable number... depending on how sure you think you are that no other planet in this solar system has intelligent life.

As far as exoplanets you would be a fool to assert that any we have found do not have intelligent life, we simply don't know.
FrankHerbert
1 / 5 (2) Apr 13, 2011
Modernmystic is playing semantics. Instead of saying what he really believes that intelligence is unique (i.e. the christian god created it) he's claiming he believes intelligence is "rare" (a more reasonable opinion than his own). Technically unique is rare and he's using word games to make his position seem more reasonable and scientific.
Modernmystic
1.8 / 5 (4) Apr 13, 2011
There are degrees to everything...


To what degree to you think the Earth is flat?

Define rare... I would tentatively agree with you that intelligence is rare but before I commit fully you must define what you mean by rare.


My opinion is that we're almost certainly the only intelligent and technically advanced species in our galaxy, and I would not be surprised if we were the only ones in the observable universe. OTOH I would not be surprised if we found another intelligent technically advanced species within a billion ly.

As far as exoplanets you would be a fool to assert that any we have found do not have intelligent life, we simply don't know.


And you'd be a fool to assert that we do, especially since we find no evidence of such and it's highly likely that given our short span of technology they'd be more advanced than we. Again all one has to do is read the Fermi paradox, it's a compelling argument...
Modernmystic
2 / 5 (4) Apr 13, 2011
Modernmystic is playing semantics. Instead of saying what he really believes that intelligence is unique (i.e. the christian god created it) he's claiming he believes intelligence is "rare" (a more reasonable opinion than his own). Technically unique is rare and he's using word games to make his position seem more reasonable and scientific.


FrankHerbert is playing God, he's claiming to be able to read minds instead of actually asking me my opinion he's asserting it for me.

FTR my opinion is that intelligent technically advanced life is extremely rare and POSSIBLY unique to the observable universe, intelligent life is very rare, PROBABLY unique to our galaxy, multi-cellular life is also rare but probably not unique to our system within the galaxy, and that single celled life is probably quite common.

That's all just opinion, but it's my ACTUAL opinion. As opposed to the feces FH just threw at the wall (again).
FrankHerbert
1 / 5 (2) Apr 13, 2011
Ok well god didn't make the earth or sun the center of the universe. He must have made our galaxy the center then!

Lol your thinking is so transparent.

In case I am wrong, please propose to me an alternative explanation for you assertion that intelligent life is "probably unique to our galaxy" even though you believe "single celled life is probably quite common." Why do you think our galaxy is unique?
J-n
not rated yet Apr 13, 2011
I'm still wondering why my saying that i believe that while likely, i was not sure WHERE the life was.. was a cop-out.

Seems more like Modernmystic was looking for someone to argue with.

Discounting Non-Scientific beliefs, The probability of there being another earth like planet in the universe is close to 100% (in fact there are probably Many Billions). The probability of there being life on one of those Many Billions is what the COMMENTS argument is about - Not what the article is about.

Those that believe in the bible should be believers in Non-Human Intelligence. Infact any Christian who even thinks about there not being Non-Human Intelligence has in fact committed a Sin.

You See, God (as described in the bible) Is an intelligence, that is NOT human (we are made in the IMAGE of god not as a copy of god). Denying (verbally or mentally) that there is this Extra-Terrestrial (not born on earth) Intelligence is a sin.
J-n
not rated yet Apr 13, 2011
Luke 12:8-10: I tell you, whoever acknowledges me before men, the Son of Man will also acknowledge him before the angels of God. But he who disowns me before men will be disowned before the angels of God. And everyone who speaks a word against the Son of Man will be forgiven, but anyone who blasphemes against the Holy Spirit will not be forgiven.

This would mean that those who are christian, and do not believe in Extra-Terrestrial Intelligence are Blasphemous and Committing an UNFORGIVABLE SIN.
Modernmystic
1.8 / 5 (5) Apr 13, 2011
Ok well god didn't make the earth or sun the center of the universe. He must have made our galaxy the center then!

Lol your thinking is so transparent.

In case I am wrong, please propose to me an alternative explanation for you assertion that intelligent life is "probably unique to our galaxy" even though you believe "single celled life is probably quite common." Why do you think our galaxy is unique?


I didn't say our galaxy was special I said I think that intelligent life is rare and intelligent technically advanced life is possibly unique. That it happens to reside in the milky way is totally irrelevant, and inconsequential...except for you trying to paint me as some kind of evolved young Earth creationist apparently. What other significance it has is lost on me.
Modernmystic
1 / 5 (1) Apr 13, 2011
I'm still wondering why my saying that i believe that while likely, i was not sure WHERE the life was.. was a cop-out.


Because it wasn't that would be MY poor reading comprehension.

Apologies.
Modernmystic
1 / 5 (2) Apr 13, 2011
Luke 12:8-10: I tell you, whoever acknowledges me before men, the Son of Man will also acknowledge him before the angels of God. But he who disowns me before men will be disowned before the angels of God. And everyone who speaks a word against the Son of Man will be forgiven, but anyone who blasphemes against the Holy Spirit will not be forgiven.

This would mean that those who are christian, and do not believe in Extra-Terrestrial Intelligence are Blasphemous and Committing an UNFORGIVABLE SIN.


And those who don't believe in intelligent design would be ignoring the designer?

Uh yeah, that's sarcasm. I have to say that because atheists have shite sense's of humor and/or assume that no one else has the right to make fun of religion or their own positions but them...
Modernmystic
1 / 5 (1) Apr 13, 2011
Oh and I did make a mistake in my earlier statement of opinion it should read as follows:

FTR my opinion is that intelligent technically advanced life is extremely rare and POSSIBLY unique to the observable universe, and PROBABLY unique within our own galaxy, intelligent life is very rare, POSSIBLY unique to our galaxy but PROBABLY not, multi-cellular life is also rare but probably not unique to our system within the galaxy, and that single celled life is probably quite common.
Ethelred
3 / 5 (2) Apr 14, 2011
Oh and it only takes a few million years to colonize a galaxy WITHOUT FTL...
Ignoring the cost yes. Reaching even 10 percent of the speed of light would require a huge amount of reaction mass no matter what the power source. Really high relativistic velocities have a serious problem with collisions with mere dust specks on top of that.

I am not saying it can't be done. I am saying it can't be done with anything close to present SCIENCE as opposed to present technology. Either a magic space drive or serious changes in human lifespan are going to be needed. Nanotech of the magic fairy dust variety would help. Generation ships at one percent C would need to be VERY large to carry enough people to bother with. Which means expensive. As in the whole planet spending a high percentage of the GDP for decades to build even one. Then centuries of travel time and centuries at the least for a colony to produce it's own generation ship.

Ethelred
Ethelred
3 / 5 (2) Apr 14, 2011
As far as exoplanets you would be a fool to assert that any we have found do not have intelligent life, we simply don't know.
No. You would only have to be a bit reasonable. Hot Jupiters are simply very unlikely to support technological life or life at all.

"probably unique to our galaxy"
I think that was an accident. From the rest of his post you can tell he meant unique IN our galaxy. Which is possible but I think it more likely that there has been some other technological species in the galaxy. But it wouldn't surprise me a lot if we are the only one because we could be the first.

Ethelred
Ethelred
3 / 5 (2) Apr 14, 2011
This would mean that those who are christian, and do not believe in Extra-Terrestrial Intelligence are Blasphemous and Committing an UNFORGIVABLE SIN.
Now that is a bizarre interpretation. Unless you are claiming that angels are aliens from another planet. Which would still be bizarre. Unless you are using the Book of Urantia as a supplement. Which would be even weirder than using the Bible to decide about the existence ET.

Ethelred
DamienS
5 / 5 (3) Apr 14, 2011
Either a magic space drive or serious changes in human lifespan are going to be needed. Nanotech of the magic fairy dust variety would help. Generation ships at one percent C would need to be VERY large to carry enough people to bother with. Which means expensive.

You could have a relatively modest ship manned by intelligent robots who could be hibernating most of the time. When a habitable planet is in 'sensor range', they could unfreeze human eggs and sperm, fertilize and implant the egg into an artificial womb and await the birth of a bunch of babies. The AIs would raise and educate the children until grown and then help to settle the habitable world.

This avoids many of the resource and expense type problems. You just need a long lasting power source, sophisticated intelligent robots and better IVF techniques. Still a tall order, but much more doable, and if it fails, no big deal as no lives would be lost in transit.
CHollman82
3 / 5 (2) Apr 14, 2011
There are degrees to everything...


To what degree to you think the Earth is flat?


A very small degree... It is flattened at the poles and elongated at the equator.

My opinion is that we're almost certainly the only intelligent and technically advanced species in our galaxy, and I would not be surprised if we were the only ones in the observable universe. OTOH I would not be surprised if we found another intelligent technically advanced species within a billion ly.


So... you would not be surprised either way... The observable universe is > 1Bly

As far as exoplanets you would be a fool to assert that any we have found do not have intelligent life, we simply don't know.


And you'd be a fool to assert that we do


Yes I would, luckily I have not... I said we don't know.
CHollman82
1 / 5 (1) Apr 14, 2011
In fact, the observable universe is about 93 billion light years (with a volume of 41 decillion cubic light years!)... so your statements make no sense, which means you have no idea what you are talking about.
ZephirAWT
Apr 14, 2011
This comment has been removed by a moderator.
J-n
3 / 5 (2) Apr 14, 2011
Now that is a bizarre interpretation. Unless you are claiming that angels are aliens from another planet. Which would still be bizarre. Unless you are using the Book of Urantia as a supplement. Which would be even weirder than using the Bible to decide about the existence ET.

Ethelred


My argument is as follows, according to the Christian Bible, god is alive, and intelligent. God cannot be From earth as God was who created earth. This means that god is an Extra-Terrestrial (not of earth) Intelligence.

The Christian God, if real, would be an ET. Therefore all Christians should believe in Extra-Terrestrial life, as it's central to their religion. If they deny this fact, they are committing blasphemy against their god, which is considered one of the highest of all sins.

Moebius
1 / 5 (1) Apr 14, 2011
(I'd have thought that the main energy problem with a full Dyson sphere would be to get rid of the waste heat.
In David Brin's last Uplift War book he had a modified Dyson Sphere because it turns out that they have problem with waste heat. They need some really serious radiators to dump the heat if they are to have a high energy capture rate.

Ethelred


Brin isn't a scientist and his writings on a Dyson sphere are not definitive (yes, I know his science is a collaboration with his readers). The whole point of building one would be to capture every bit of energy from the sun on the assumption that the species was interested in surviving as long as possible and stuck with that one sun. If you have the means to move a stellar system, why would you want to? Anyone who builds a Dyson sphere does so because they are not going anywhere and know that interstellar travel is not possible. If it is, you would build small ships, not a Dyson sphere and try to move it.
yyz
5 / 5 (3) Apr 14, 2011
"In fact, the observable universe is about 93 billion light years

I'd more careful about using of "fact" word in this connection.

http://www.techno...v/26333/"

CH was referring to the size of the *observable* universe. Your own source says the same:

"That makes the visible universe some 90 billion light years across."

The paper you refer to finds that the universe is "at least 250 times bigger than the Hubble volume". And the Hubble volume is smaller but similar to the size of the *observable* universe.

http://en.wikiped...e_volume

http://en.wikiped...universe

So, what was the problem again?

(Do you ever read (and understand) the sources you give to support many of your posts? You know, beyond the title or abstract.)

Modernmystic
2 / 5 (4) Apr 14, 2011
A very small degree... It is flattened at the poles and elongated at the equator.


So... you would not be surprised either way... The observable universe is > 1Bly


Right, I wouldn't be surprised either way.

Yes I would, luckily I have not... I said we don't know.


Well we don't see any evidence of any, which is not to say there aren't any. Then again a lack of evidence is also evidence.

In fact, the observable universe is about 93 billion light years (with a volume of 41 decillion cubic light years!)... so your statements make no sense, which means you have no idea what you are talking about.


Please tell me where I said the observable universe was 1 billion ly, I do in fact know it's far larger than that. I said it wouldn't surprise me either way. I didn't bet on the Packers to with the Super Bowl this year, but I wasn't surprised when they did...surprise would have been if a professional baseball team pulled it off...
ZephirAWT
Apr 14, 2011
This comment has been removed by a moderator.
CHollman82
1 / 5 (1) Apr 14, 2011
Then again a lack of evidence is also evidence.


No it is not...

Please tell me where I said the observable universe was 1 billion ly, I do in fact know it's far larger than that.


My opinion is that we're almost certainly the only intelligent and technically advanced species in our galaxy, and I would not be surprised if we were the only ones in the observable universe. OTOH I would not be surprised if we found another intelligent technically advanced species within a billion ly.


If you weren't implying that observable universe is less than a billion ly in this statement then it was nonsense... pure gibberish. You must have meant that you would not be surprised to find intelligent life and you would also not be surprised not to find intelligent life within 1 billion ly... which is using a lot of words to say nothing.

I wouldn't be surprised if it rained tomorrow... I also wouldn't be surprised if it didn't rain tomorrow... yay I can't lose!
Modernmystic
1 / 5 (1) Apr 14, 2011
No it is not...


So if I accused you of murder and could produce no evidence that you did it you should be convicted?

Does the fact that we found no WMD in Iraq mean something or nothing?

If you weren't implying that observable universe is less than a billion ly in this statement then it was nonsense...pure gibberish. You must have meant that you would not be surprised to find intelligent life and you would also not be surprised not to find intelligent life within 1 billion ly... which is using a lot of words to say nothing.


So if you said you wouldn't be surprised if you saw an ant outside your house or if you saw one in China would be saying nothing? You lost the point, here's your consolation lollipop, now move on *pats CHollman on the head*

I wouldn't be surprised if it rained tomorrow... I also wouldn't be surprised if it didn't rain tomorrow... yay I can't lose!


What were you hoping to win?
Bog_Mire
1 / 5 (1) Apr 14, 2011
wow mm must have well developed leg muscles with all that back-pedalling! Never have I seen such furious back-pedalling. If back-pedalling was an Olympic sport.......
Modernmystic
1 / 5 (1) Apr 14, 2011
wow mm must have well developed leg muscles with all that back-pedalling! Never have I seen such furious back-pedalling. If back-pedalling was an Olympic sport.......


Well your medal wasn't in spelling was it? Try "back-pedaling" :)
CHollman82
1 / 5 (1) Apr 14, 2011
So if I accused you of murder and could produce no evidence that you did it you should be convicted?


Non sequitur... this does not follow from our previous exchanges.

Does the fact that we found no WMD in Iraq mean something or nothing?


It means exactly what you said... we found no WMD's in Iraq... Why do you want it to mean something else?

So if you said you wouldn't be surprised if you saw an ant outside your house or if you saw one in China would be saying nothing?


What? You said you wouldn't be surprised if x and also that you wouldn't be surprised if not x... your example of ants in China does not represent the problem... the problem is that you said you would not be surprised in either of two diametrically opposed cases... which is saying nothing at all about which case you believe to be more likely, except that you have no opinion... in which case you shouldn't have said anything in the first place.
DamienS
5 / 5 (3) Apr 14, 2011
The definition of observable Universe just depends on the instruments, which we are using for observations. With using of naked eye the diameter of observable Universe wouldn't large

That is not the definition of observable universe. The observable universe is defined by what is in principle possible to observe, whether or not it actually has been.
Bog_Mire
1 / 5 (1) Apr 15, 2011
pedaling is incorrect. unless your spelling comes from some other unknown dictionary, or unless you are just a garden variety knob head who presumes to know everything yet really has his head up his arse?
Modernmystic
1 / 5 (1) Apr 15, 2011
It means exactly what you said... we found no WMD's in Iraq... Why do you want it to mean something else?


What it means, since you're being so thick, is that the absence of WMD was evidence that there were no WMD. It's really not that hard to grasp...really it's easy if you try even for you.

What? You said you wouldn't be surprised if x and also that you wouldn't be surprised if not x...


So I wouldn't be surprised if I saw an ant outside my house, and I wouldn't be surprised if I didn't see an ant if I visited China either. It makes perfect sense and works as well either way. It means that while something is likely you're not necessarily surprised if it does or doesn't happen, and so vice versa. This is where your idea of "degrees" would actually be applicable (as in degrees of likelihood) which is exactly what I was trying to convey and did very succinctly.

Modernmystic
1 / 5 (1) Apr 15, 2011
pedaling is incorrect.


http://www.merria...pedaling

:)
PaulieMac
5 / 5 (3) Apr 15, 2011

Brin isn't a scientist


Brin is an astrophysicist, actually...
d_robison
5 / 5 (2) Apr 15, 2011
Wow, I came back to check my earlier post, and its amazing how much nonsense and how many off-topic conversations can be found in one Physorg article discussion section. It made for a very entertaining lunch break! Instead of reading every single comment to find where people began straying from the core discussion, I decided that I would add to the off-topic conversation with this comment.
Modernmystic
2 / 5 (4) Apr 15, 2011
Wow, I came back to check my earlier post, and its amazing how much nonsense and how many off-topic conversations can be found in one Physorg article discussion section. It made for a very entertaining lunch break! Instead of reading every single comment to find where people began straying from the core discussion, I decided that I would add to the off-topic conversation with this comment.


Have you ever noticed if you have a conversation with another person for more than about 10-20 minutes the topic changes? Most folks accept this as human nature...why should the internet be any different?
J-n
not rated yet Apr 15, 2011
Strangely, though, in this case it strayed from the topic of the article in 5 posts or so.
Bog_Mire
1 / 5 (1) Apr 15, 2011
oh OK then, I get it, you are just a garden variety knob head who presumes to know everything yet really has his head up his arse.

Fair enough then, that settles that.

And thanks for pedalling your version of reality; an enlightening insight to the inner workings of a fraudulent crankster's mind. A bit scary, but enlightening. Also please dont smile at me with your posts; there is never anything funny.
Ethelred
3 / 5 (2) Apr 16, 2011
This means that god is an Extra-Terrestrial (not of earth) Intelligence. Yep. A silly interpretation and irrelvant to the discussion in any case.

A god of that sort is Etra-UNIVERSAL and not something that evolved within the universe which was what was being discussed. Do try to use relevant examples.

The Christian God, if real, would be an ET.
Not if you are using actual English. Its an EU not an ET.

You really should have noticed that I mentioned angeles and they too are EUs not ETs.

Ethelred
Ethelred
3 / 5 (2) Apr 16, 2011
Brin isn't a scientist and his writings on a Dyson sphere are not definitive
He was a scientist and still does consulting for the government. And he wasn't the person that did the thermodynamic work on the Dyson Sphere. Sorry I don't remember who did it.

(yes, I know his science is a collaboration with his readers).
Pretty sure that isn't right either. He gets feedback like every other writer but his writings are his own. Except for that collaboration he made with another professional scientist on Halley's Comet.

He isn't a real scientist anymore. I think he got enough to retire when Postman was botched into a movie.

capture every bit of energy from the sun
I know that. You still have to get rid of the waste heat and that MUST equal the heat input minus the energy stored. I don't think energy storage is a long term solution to cooling.

More
Ethelred
3 / 5 (2) Apr 16, 2011
If you have the means to move a stellar system, why would you want to?
To get to the other side. As comfortably as possible.

First assume a spherical chicken of uniform density.

Anyone that can build a Dyson Sphere is capable of interstellar travel. One way or another.

Ethelred
Starbound
4.8 / 5 (5) Apr 16, 2011
I've only read about half the posts. One guy said early on that if there were alien communication networks we would have detected them by now. I'd like to point out that an alien civilization actually would have to go through a lot of trouble to announce its presence.

Any EM signal disperses as it travels through space, and even if a distant civilization shined a message laser right at Earth only a handful of photons would impinge upon even the largest receivers. As it stands we are just barely being able to image entire planets let alone message signals.

Detecting a 'starship' in our solar system is also dubious since we are capable of only detecting a small percent of asteroids and comets within our own system.

Mark
SemiNerd
not rated yet Apr 16, 2011
It is very likely that the neighborhood where a star is born influences the chance of a stable system forming even more than the likelihood of the system forming to begin with. Evidence shows most stars are born with lots of other stars relatively nearby. The OORT cloud extends roughly a few light months from our sun, more massive stars probably have gravitationally bound debris even further out. The point here is that very early in a stars life, the chances of a brush by (within say .1 light year) is pretty high. This would cause a lot of debris to pelt the inner system. A closer collision (say several light weeks), could cause lethal complications.
WhiteJim
1 / 5 (1) Apr 17, 2011
All life forms we have discovered so far is related and can be traced back to a single life form. We have not found any alien life on Earth. This tells us that creating life from nothing is not easy and is very rare. Otherwise we shoud have different examples on earth of life that developed independantly. The conclusion is that life on earth must be of alien origin and the earth was seeded from life that spontaniously generated on some other planet and brought here through the scratering of astroids and comets and related events. To suggest that this planet out of the trillions of planets in our galaxy was the one to generate life spontaniously is only a religion and cannot be based on scientific thought. If life generated spntaniously here and elsewhere then we would have evidence of different unrelated life on earth from the actions of the astroids, comets, and all the churnings going on for the billions of years of our gallaxies existence.
WhiteJim
1 / 5 (1) Apr 17, 2011
... from the above conclusion we can also conclude that all life we will find existing elsewhere in our gallaxy will be similar and related to our life forms here on Earth. The differences will be evolutionary.
Ethelred
3.7 / 5 (6) Apr 17, 2011
All life forms we have discovered so far is related and can be traced back to a single life form.
True.

This tells us that creating life from nothing is not easy and is very rare.
That depends on what you mean by easy or rare. Life started EARLY on Earth. As far as we tell it started about as soon as life could be sustained which strongly implies that it is NOT hard.

Otherwise we shoud have different examples on earth of life that developed independantly.
False. IF any PARTICULAR start is of low odds and (as seems probably) there are many possible self or co reproducing molecules then there should eventually be one getting started. The ocean is large and a hundred million years is a long time. Odds of one in a million per year per mile of shoreline for any particular molecule is likely to occur over that length of time BUT only ONE is likely at any given time.

More
Ethelred
3.7 / 5 (6) Apr 17, 2011
Once that occurs the molecule and its descendants will rapidly consume the free organics thus making it unlikely for any other molecule to get started. Thus what ever starts first will be the ancestor of all life on any planet.

The conclusion is that life on earth must be of alien origin
Based on bad assumptions.

To suggest that this planet out of the trillions of planets in our galaxy was the one to generate life spontaniously is only a religion
Silly comment based on based on poor assumptions. Life started early. There is no reason to assume the odds were one trillions of planets. And that number, TRILLIONS IN OUR GALAXY, shows you don't have a clue as that is off by a full order of magnitude at least.

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Ethelred
3 / 5 (4) Apr 17, 2011
If life generated spntaniously here and elsewhere then we would have evidence of different unrelated life on earth
Nonsense. If it started elsewhere it would have to travel light years of irradiated vacuum after evolving on a nice wet, warm, low radiation environment. Now that is improbable.

from the above conclusion we can also conclude that all life we will find existing elsewhere in our gallaxy will be similar and related to our life forms here on Earth
And from all the above I conclude that you have been reading too much nonsense from the late Sir Dr. Hoyle. A very good scientist that became a crank because he wanted an unchanging Universe.

Ethelred
FrankHerbert
2.3 / 5 (3) Apr 17, 2011
@WhiteJim

It's entirely possible life spontaneously generated itself more than once on Earth. However, it makes perfect sense that all current life would be descended from only one of these though. For example, I'm assuming the processes of life are many orders of magnitude more efficient than anything the common universal ancestor would have possessed. Similarly, any early life not related to the universal common ancestor probably would have had some severe efficiency problems compared to the universal common ancestor. It makes sense that only one sapling of life could have survived to form the tree we have today.
trekgeek1
not rated yet Apr 17, 2011
1, there aren't billions of stars out there with 3 or more terrestrial planets.


While usually you're really into the math on stuff, this one you dropped the ball.

There are between 10 sextillion (10000000000000000000000) and 1 septillion stars in the Universe (Very rough estimate, we will use the very low number of 1 sextillion (1000000000000000000000) stars), which means even if only 1 in a million stars have 3 or more planets this leaves us with 1 quadrillion stars with 3 or more planets.

That's if only 1 out of every Million stars has 3 planets or more... and this study said that 40% of all stars have 1 or more planet, that's 400 quintillion (400000000000000000000) stars (if there is only 1 sextillion)with one or more planets.

Your numbers are off by a few orders of magnitude.


So...where's ET then?....


There was an entire article on the Fermi paradox this last week. Go read that; there are plenty of ideas.
WhiteJim
1.2 / 5 (5) Apr 17, 2011
Life started EARLY on Earth. As far as we tell it started about as soon as life could be sustained which strongly implies that it is NOT hard.


Life was landing on earth constantly from before it could sustain life... ... that is the reason why it took hold so early or as soon as the earth could allow it to thrive.

Your speculation that it spontaniously arose early makes it soo easy we should see it and replicate it now in a laboratory just as easily by manipulation... but we can't. So to say that nature can spontaniously make life easily by chance it whimsical.

Making life by chance is difficult. Maintaining life once it does come about is a lot easier.

organisms can travel thousands of light years through space to seed other habitable locations, plannets, comets, astroids, moons etc... trllions of potential carriers of life to move it around the galaxy... the galaxy is full of life everywhere and it is all related to the life we have on earth.
DamienS
5 / 5 (4) Apr 17, 2011
Life was landing on earth constantly from before it could sustain life

How do you know this? What proof do you have for this assertion?
Your speculation that it spontaniously arose early makes it soo easy we should see it and replicate it now in a laboratory just as easily by manipulation but we can't

No, not yet. But we are getting closer to unraveling the minimum requirements that took nature millions of years, after all, to get started. See work by Dr Craig Venter, for example.
So to say that nature can spontaniously make life easily by chance it whimsical.

I don't think that anybody is saying that life started by chance alone. Certainly there was much chance mixing of elements and energy flows in the environment, but there was also the guiding hand of physical law which makes certain combinations and assemblies more likely than pure, unconstrained chance alone.
Making life by chance is difficult.

Yes, it is. But that's not how it happened as I explained
DamienS
5 / 5 (4) Apr 17, 2011
Maintaining life once it does come about is a lot easier.

Yes, that's so.
organisms can travel thousands of light years through space to seed other habitable locations, plannets, comets, astroids, moons etc.

That's complete speculation and very, very unlikely (for those distances). However, that mechanism is plausible within a star system.
the galaxy is full of life everywhere and it is all related to the life we have on earth.

The second part of that comment is an unfounded leap of faith. The first part has a much better chance of being true (though I would not use the word 'everywhere').
Ethelred
3 / 5 (2) Apr 18, 2011
While usually you're really into the math on stuff, this one you dropped the ball.
No. He said THIS galaxy. Not the Universe.

Original statement
trillions of planets in our galaxy

Your numbers are off by a few orders of magnitude.
Now who's reading is off by orders of magnitude. I double checked about it being OUR GALAXY not the whole Universe.

Ethelred
Ethelred
3 / 5 (2) Apr 18, 2011
Damien you beat me. I was wrote pretty much the same thing. Most likely with way more missing words when I scrolled down to post there was yours.

Ethelred
WhiteJim
1 / 5 (2) Apr 18, 2011
Maintaining life once it does come about is a lot easier.

Yes, that's so.
organisms can travel thousands of light years through space to seed other habitable locations, plannets, comets, astroids, moons etc.

That's complete speculation and very, very unlikely (for those distances). However, that mechanism is plausible within a star system.


Using the two rabbit analogy... after a year you have tens of thousands of rabbits starting off with just two... The trillions upon trillions of possible carriers of life ... from specs of dust to moons orbiting gas giants etc. all moving and banging into each other for billions of years in our galaxy would spread virus and bacteria size life throught the galaxy after it started many billions of years before the earth's solar system condensed from its gas cloud. Like I said, it was much easier for life to get here than is was to start here. No life has been created or seen to be created. Only one kind, why?
Ethelred
3.7 / 5 (6) Apr 18, 2011
galaxy would spread virus and bacteria size life throught the galaxy after it started many billions of years before the earth's solar system condensed from its gas cloud
Life can't start on early stars as they don't have enough heavy elements to produce sufficient complexity. The galactic core is hostile to life so that leaves the middle zones like ours where the stars tend to be pretty far apart and farther out they are way too far apart. So life couldn't have started very early.

Then there is the matter of life surviving transit. It is far more likely that life started here than survived for millions of years in transit. Viruses can't reproduce on their own so I don't see why you even bothered even bringing them up. There is no evidence that bacteria can survive for millions of years while in a vacuum and irradiated by UV, X-rays, gamma rays, and cosmic rays which are ions and not rays.

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Ethelred
3.7 / 5 (6) Apr 18, 2011
Like I said, it was much easier for life to get here than is was to star here.
Like I said that is crap.

Only one kind, why?
What ever kind of life gets started will consume the raw material needed for life to get started the first time. Which I already pointed out. If you don't like that then say why.

Fact is I all ready covered EVERYTHING you just said and all you have done is repeat it.

Ethelred
J-n
not rated yet Apr 18, 2011
While usually you're really into the math on stuff, this one you dropped the ball.
-No. He said THIS galaxy. Not the Universe.
Original statement
trillions of planets in our galaxy

Your numbers are off by a few orders of magnitude.

Now who's reading is off by orders of magnitude. I double checked about it being OUR GALAXY not the whole Universe.

Ethelred


I originally posted that QC was off by a few orders of magnitude. I posted the math in response to:

I think what you should take from this is:

1, there aren't billions of stars out there with 3 or more terrestrial planets.


There was no mention of galaxy in his statement or any statement before his. The article does not limit it's discussion to just our galaxy, I had assumed he was not limiting him self either.

I told QC that he dropped the ball and did the math to prove it back on the 6th post of this article. I am not sure where before then it mentions galaxy at all, article or comments.
d_robison
not rated yet Apr 18, 2011
Wow, I came back to check my earlier post, and its amazing how much nonsense and how many off-topic conversations can be found in one Physorg article discussion section. It made for a very entertaining lunch break! Instead of reading every single comment to find where people began straying from the core discussion, I decided that I would add to the off-topic conversation with this comment.


Have you ever noticed if you have a conversation with another person for more than about 10-20 minutes the topic changes? Most folks accept this as human nature...why should the internet be any different?


Correct, but on too many occasions I have seen intelligent debates turn into name-calling and childish banter. There is too much speculation claimed to be fact for my taste. This comment was not meant for the few on this thread that are ACTUALLY debating such as yourself, Ethel, and some others. I was merely stating how amused I was at how many of the 100+ comments are nonsense
Modernmystic
1 / 5 (1) Apr 19, 2011
There was an entire article on the Fermi paradox this last week. Go read that; there are plenty of ideas.


I did, I'm posting here to have a conversation about the idea. I'm assuming you know the difference between reading and discussion...
WhiteJim
1 / 5 (1) Apr 19, 2011
Like I said that is crap.

Ethelred


Good thing that you are honest.

If life can develop independantly fairly easily as you believe, why have we not been able to see life spontaniously arise in a lab? Why can we not find even one other example of life that was different than us?

The recent NASA anouncement about having found alien life on earth was shown to have evolved from our usual earthly life.

It is very hard to spontanioulsy generate life is the conclusion. If it is so hard then it could have been gerenated only once and the spread throughout the galaxy. This will likely be proven soon by finding microbial life on astroids and comet and space dust.

I said virus and bacteria size life can travel thousand of light years in space by astrocollisions.
Ethelred
3 / 5 (2) Apr 19, 2011
If life can develop independantly fairly easily as you believe, why have we not been able to see life spontaniously arise in a lab?
Do what read what you reply to? I covered that.

Why can we not find even one other example of life that was different than us?
Covered.

The recent NASA anouncement about having found alien life on earth was shown to have evolved from our usual earthly life.
Of course.

It is very hard to spontanioulsy generate life is the conclusion.
I suspect it is low odds per reaction. Thus it is likely to occur once and then all the raw material gets used up by the descendants. And this is the third time I said that in this discussion. If you disagree give a reason. Does the concept of back and forth completely escape you?

If it is so hard then it could have been gerenated only once
No. There is no reason to believe it is that hard.

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