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'Hundreds of Worlds' in Milky Way
Raphael Emportu writes "BBC news is reporting
that rocky planets, possibly with conditions suitable for life, may be more common than previously thought in our galaxy, a study has found.
New evidence suggests more than half the Sun-like stars in the Milky Way could have similar planetary systems.
There may also be hundreds of undiscovered worlds in outer parts of our Solar System, astronomers believe.
Future studies of such worlds will radically alter our understanding of how planets are formed, they say."
First 9, then posibly 10, then back to 9, then 8.. now we have..
"Our old view, that the Solar System had nine planets will be supplanted by a view that there are hundreds if not thousands of planets in our Solar System,"
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No shit that there are other planets like ours out there. The incomprehensibly massive scale of the universe dictates it to be true, statistically-speaking.
Today, children receive next to no education in the field of astronomy. Were they to have a proper understanding of what lies beyond Pluto, they'd probably grow up to realize how silly it is to believe that there is only one planet like Earth.
Now, if we only had some means of reaching it...
The speed of light is a barrier like few the humanity has ever found.
Interesting, considering that just last night I was watching a documentary, on BBC4 no less, about rare earth theory and how miraculous it was that the conditions on earth are as they are.
...
Funny but, I couldn't shake the feeling that the reason conditions here on earth are so 'perfect' for life as we know it was more to do with life as we know it evolving to fit the conditions
Invaders must die
Wouldn't it be feasible that intelligent life could arise on a planet that is liquid? As long as the temperature of the liquid is sufficiently stable, there are sufficient chemical building blocks and there is not too much current, single cell organisms and then multi cell organisms could emerge.. Or am I wrong?
Anyhow, cool to hear that being the third rock from the sun is nothing special.
Stop the brainwash
I thought something similar. It's like in HHGTTG where they put all the hairdressers onto one ship.
which is totally what she said
... there may be hundreds of worlds in the solar system. In the Milky Way, expect trillions. The distinction between the Solar System and the Galaxy is a subtle one, similar to that between a grain of sand and Saudi Arabia, so it's easy for the likes of the BBC to confuse the two.
Real Daleks don't climb stairs - they level the building.
Given hundreds of worlds within our own galaxy, if we apply the Drake Equation, there's a good chance that there's another intelligent species out there, although the chances of it being of a sufficient technological development to make its presence known is slim. Also, the 'accepted values' for the various parts of the Drake equation are subject to (sometimes intense) debate.
This being said, given that most of these "nearby" worlds are tens of thousands of light-years away, with the current state of our technology, we might as well be alone.
____
~ |rip/\/\aster /\/\onkey
...planets, possibly with conditions suitable for life, may be more common than previously thought... I have heard this so many times that I'm losing track on how common we previously thought they were.Yes, and the Global Warming is more severe than previously thought, we hear every so often.
In realty it's colder than last year and the Universe have less habitable solar systems than we were told last year.
- Thomas
welcome out new United Federation of Planets overlords...
so we can go to them?
If there are only hundreds of earthlike planets what are the extra Stargate addresses for?
Ubiquitously - A Ubiquity Developer Community
a planet would not be 100% uniform liquid at room temperature. You don't get planet sized blobs of water. Our planet is a lot of liquid around a fairly small probably solid iron core. The most common liquid component of planet earth by a long way is magma. The solid rock crust and liquid water in the seas is so insignificant by comparison it is surprising we even bother to talk about it. Anyhow what you were probably thinking about is a planet with a surface completely covered by liquid water or something like it. I think something could arise on such a planet, at the surface (or possibly below it if we are allowed to assume a hot core with volcanic vents.) You could get algae mats forming and sinking when they die off. Huge floating mats could then provide an ecosystem for other things to evolve around. At some point there could be fishlike animals under the mats and amphibious creatures walking on top of the mats. I can't see any real limit to the size and stability of the floating mats. Any creature looking to develop technology would have to use organic materials, which makes electronics a bit tricky. In terms of leaving the planet, fuel and a launch pad wouldn't be too tricky, building the rocket might be though.
except Europa. I'll not be attempting any landings there.
Squid, cuttlefish, and other similarly baleful creatures are all members of the cephalopod family, characterized by HUGE EYES, BEAKS, INTELLIGENCE, and AMBITION.
I'm all for shipping grammar nazis off to the most distant rock available.
;)
By the way, it's "later", not "latter"
The speed of light is not a deal-breaker. It means that, from *our* perspective, we'll send people to distant planets and never hear from them again. But from their perspective, it may be a few years. If interstellar travel actually happens, then the speed of light issue is just a managable logistical issue. It means that space-farers must be able to think for themselves. They already must be self-sufficient in other respects.
If there is a deal-breaker, then it is contruction and propulsion of such a craft. The vaster the craft, then the more unlikely it's construction. We might be able to fire ourselves off in a single direction, but how do we slow down, and what if we need to change course. If we need to come home, then we've doubled the energy required!
Then there are complex issues with people - our fragile minds and bodies. How do we react to the stress of space-travel, can we do it?
The speed of light seems like a comparatively simple issue.
Like all pain, suffering is a signal that something isn't right
So, instead of humanity spending trillions of dollars on exploring the galaxy we opt for killing our own species to hell and back. If an Armageddon asteroid, zombie outbreak or other humanity ending event occurs I will have no sympathy for us. We are collectively imbeciles.
The question is whether we want to have any planets. From Earth, for example, you could construct 10000000 rotating hollow cylinders, 1000x1000km each, with reasonable gravity, perfect weather, safety from radiation, and sustainability for billions of years. The total usable area will be 1e11 square km, 196 times larger than the Earth. It is also portable and redundant, ensuring that the entire civilization is not wiped out by an asteroid. It can remain usable after the Sun burns out; you can install a fusion generator and mine Jupiter for fuel for a very very long time. So tell me again why we need a planet?
While tool use is certainly probable in an aquatic species that evolved intelligence, I would doubt that any such species would progress past the stone age in terms of technology. However, they may evolve a very advanced society, afterall, the Ancient Egyptians and Mayan cultures also were just progressing out of the stone-age yet they had highly advanced societies.
Why would they be limited to the stone age? If you assume that they are fully aquatic and not amphibian-like then they would lack one of the major requirements for progression beyond the stone age. Fire. Granted I may be taking a short sighted view of this, but without easy access to fire, it would be VERY difficult for such a society to develop anything beyond basic stone age tools.
I suppose it would be possible for them to utilize a volcano as a source of energy to smelt metals. But I would imagine that smelting in an aquatic environment would have some severe drawbacks. (even if we ignore the problem associated with oxidation of metals)
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Future studies of such worlds will radically alter our understanding of how planets are formed
"All That Is Solid Melts Into Air"
This statement (from Marx, I think) fits perfectly in our understanding of the universe.
Apparently not, even at the BBC. What they were saying is that there could be hundreds of worlds in the solar system, not in the galaxy. (They meant in the Kuiper belt, far outside of Pluto and Neptune.)
We have already found 273 extra-solar planets in the galaxy. No one doubts now that there are millions, if not billions, in the galaxy, and a puling "hundreds" of Earth type planets in the galaxy would strike most people following this research as a very low estimate.
From the article : "Some astronomers believe there may be hundreds of small rocky bodies in the outer edges of our own Solar System, and perhaps even a handful of frozen Earth-sized worlds."
I would also regard this as almost not news at all, given the rapid rate of discovery of TNOs (Trans Neptunian Objects), three of which so far are the size of Pluto or larger.
i thought for sure that would be a link to sponge bob ...
Seriously, to think Earth is or could be the only planet capable of sustaining life is highly improbable.
I am going to go out on a limb here and say, there is inteligent life out there and we are not ready to meet it.
Or ready or not we better grow up and deal with it because we just became as insignificant as a grain of sand.
These articles seem like they are written for those sensationalist magazines, let's write in more grown up terms.
Think people are insane now? wait when you tell them aliens have landed on our planet.
Um, they have found a lot of these (273 candidates this morning), and most of them are not in Solar System type... solar systems. That is indeed having a profound effect on research into planet formation.
BBC news [...] possibly [...] may be [...] suggests [...] could have [...] may [...] believe. [...] they say. I didn't read the study nor the article from the BBC news, but I wouldn't be surprised if they were written by the same guys who are on the staff of the Discovery 'Artificial Drama and Speculation' Channel.
How is this news?
Stachel
I disagree. I understand the argument you are trying to make, but your "1 in a million" suggestions are really more akin to wild stabs at the biggest number you can think of, than they are reasonable guesses. 1:1000000 is really an unusually small ratio, and not as common as you intimate. It certainly has no actual relation to the situations that present themselves in the formula.
You can't simply spout a bunch of hyperbole and expect to be taken seriously. Especially in reply to an article that attempts to actually determine those numbers and percentages based on facts. This kind of talk is really no different from the comedy statement that "90% of people know that you can prove anything with statistics." It's meaningless.
While we will likely have to wait a whole lot longer for meaningful answers to the Drake equation, attempts at putting fact-based numbers on the variables should be applauded, and discounting them with what amounts to emotional hyperbole should be discouraged IMO.
>If we assume that the life we know started it's existence on earth, than the odds seem pretty
>damning. All known life on earth very likely comes from one source. It all has DNA and other
>similarities. After all these billions of years that life could come to exist on earth, it may have
>only happened exactly once.
No, you're overlooking something very important. Firstly, the chemisty of the Earth now is radically different to what it was when life first appeared. This difference is largely due to... life! Life has changed the chemical makeup of the atmosphere, the soil, even the rocks and the seas over the last however many billion years.
more importanly though, and perhaps not unrelated to the above point, is that new instances of life could be spontaneously emerging on Earth right now from whatever source originally spawned our microscopic ancestors. Maybe some new miracle is occurring in that unwashed coffee mug on your desk right now! However the environment in which any life arose would already be populated by bacteria, which are present just about everywhere on Earth, but which thrive particularly well in the kind of environment that would be friendly to an emergence. The newly emerged life form would be so incredibly basic- little more than self-replicating molecules- that they'd be utterly helpless against these more evolved life-forms and would be digested and made extinct almost instantly.
In short, once life has emerged and gained a foothold, you can expect it to spawnkill any subsequent emergences of life. This means you're unlikely to witness a second spontaneous emergence of life on any given world (Unless the first ecosystem is somehow wiped out altogether, down to the very last microbe, giving the second emergence a safe environment to develop in. This would be surprisingly hard to achieve. A nuclear war almost certainly wouldn't be enough. A nearby gamma ray burst, maybe?)
I am TheRaven on Soylent News
"The incomprehensibly massive scale of the universe dictates it to be true, statistically-speaking."
(Speaking of hyperbole and statistics jokes).
doesn't tell you a whole lot. What we do know is that most of the extrasolar systems we've found also tend to have Jupiter-like and larger planets and that in the majority of cases, these planets are either fairly close to their stars or in highly eccentric orbits. Either of these conditions would tend to make any "habitable" planets less habitable. A Jupiter-like or larger planet close in or in a highly eccentric orbit would tend to destablize the orbits of any small rocky planets in the habitable zone.
There are so many things that have to come together to make our planet habitable, that I suspect these conditions are a lot less frequently found than a lot of people would hope. That's not to say I don't think is common in the universe. I do. I just think the vast majority (by several orders of magnitude) of it is going to be single-cell (or if not in the form of cells, of equivalent complexity). You need liquid water (which gives you a pretty narrow temperature range at any given pressure), you need something in the atmosphere to protect against stellar radiation (or, if it's a water planet, I suppose something in the water to protect), you need a planet that's active, but not overly active (and lots of factors go into that). Anyway, I suspect true earth-like planets are pretty rare.
The explanation for the "write" vs. "write to" distinction, at least, is pretty simple. The nouns taking the verb "write" are dative case. That's not obvious in English, but it's there, and it underlies the apparent form.
German is useful here because 1) it's the root language for English and 2) its sentence structures can be perfectly analogous. Take the German sentence Schreib deiner Mutter einen Brief which is translated word-for-word as Write your mother a letter. In German, the deiner is a clear marker that Mutter is dative. The exact same thing is happening in English, but since we don't decline our articles or possessive adjectives and rely instead on word order, it's not obvious to the typical native speaker.
So you can laugh all you want to...
See my sig:
Why, yes I have been touched by His noodly appendage. And I plan to sue.
Therefore while the 'hundreds of undiscovered planets' are technically in the Milky Way - it is totally misleading as it implies that that is all there is in the whole friggin' galaxy@!
From http://en.wikipedia.org/wiki/Milky_way we have about 200-400 Billion stars in the Milky Way galaxy, and neglecting that many may be binary systems where planets would have highly erratic and perhaps unstable orbits, and from TFA:
"Our observations suggest that between 20% and 60% of Sun-like stars have evidence for the formation of rocky planets not unlike the processes we think led to planet Earth," he said. "That is very exciting."I might not have a BS degree in math but 20-60% of even 1% (a hypothetical % of single sun like stars in the Milky Way) of 200 Billion is far more than just a few hundred.
Whats it like being dead? Are there really billions and billions of solar systems out there?
A concerned citizen
Comment removed based on user account deletion
I can understand that BBC doesn't know how to use a calculator, but a Slashdotter certainly ought to. Our galaxy is 50000 ly in radius, which comes out to 1.4e37 m2. Our solar system, taken to the orbit of Pluto, is 40 au in radius, or 2.8e24 m2. The ratio between the two is 5e12. Applied to the area of Saudi Arabia, which is 2e12 m2, we get 0.4 m2. That's a "grain" of sand 63cm on the side.
"'Hundreds of Worlds' in Milky Way" It looks like the Raphael didn't actually read this article, even the summary he posted; he is also apparently scientifically illiterate.
I always found this verse interesting, using worlds as opposed to planets. So why wouldn't there be more than one?
Just food for thought
They were saying that when I went to High School.
OK, some of these things just don't make sense - "could of", for example, which is presumably a back-formation from "could've", and "different than". But "fill out" is just idiomatic, isn't it?
Incidentally the last sentence is the most pompous thing I've read in a while. Good work.
The real question is what makes it correct? It is correct because some college prof somewhere says so, because it was stated so in some book 50 years ago, or because more then 50% of the people use it a certain way?
New words and meanings are added to the dictionary all the time. Why not in regard to this as well?
-Mark
Dovie'andi se tovya sagain.
About ten planets in our solar system. About 100 billion stars in the Milky Way. Which is about 1 trillion planets, assuming they all have solar systems comparable in size to our's.
If you take their "hundreds of planets in our solar system" as gospel, then "trillions of worlds" will fit in our galaxy nicely.
Much less in the "universe as a whole", which ought to have on the order of billions of trillions of planets.
"I do not agree with what you say, but I will defend to the death your right to say it"
My bicyles
let's look at the data that is the source for these conclusions.
"Our observations suggest that between 20% and 60% of Sun-like stars have evidence for the formation of rocky planets not unlike the processes we think led to planet Earth,"
"Our observations" means only that in a survey of sunlike stars, they identified clouds of dust around them. They haven't imaged anything, they are making the supposition that dust clouds = rocky planets, which is a leap.
Furthermore, they are presuming that there are earth-sized bodies in our own Oort cloud, which again, haven't been imaged or otherwise identified. Another huge supposition.
In both cases, I would believe that these conclusions are reasonable, and I personally believe it's LIKELY that terrestrial, rocky planetoids ARE common both in our system and galactically. But in both these cases I don't see any evidence presented that changes what was a previously widely-held guesstimate into anything more substantial than that.
To be more specific from the grossly oversimplified BEEB article: http://www.nasa.gov/mission_pages/spitzer/news/spitzer-20080217.html
The telescope used images the infrared picture of dust around target stars. Logically, the dust closer in to the stars is hotter than the dust further out (like the oort cloud).
Hot dust is 3.6-8 microns in wavelenth, cold dust is 70-160 microns. "Warm dust" at ~24 microns, is presumed to be in the 'sweet spot' - representing in our system the span from Earth to Jupiter's orbits. Looking at main-sequence stars like the sun, they see that at an age of about 300 million years, the 'signal' for warm dust just drops off. Coincidentally, this is the same time in solar evolution in which we believe our solar system was swept clean of dust by the formation of the rocky planets. So they are presuming that this process is taking place elsewhere as well.
-Styopa
Yup.
I'd also add that "different from" vs. "different than" is not clear-cut. Even in British English, "different than" is sometimes used. Bartleby says that "different than" is considered always acceptable when followed by a clause, e.g. "The book is different than I'd remembered," while "different from" should generally be used when comparing two things, e.g. "My book is different from yours."
And then, there's the British variant "different to," which IMHO makes no sense at all.
Check out my sci-fi/humor trilogy at PatriotsBooks.
One of the interesting things on earth is that fish aren't very smart...
They have as many reasons as other organisms to develop intelligence but they don't.
The reason is fairly simple...Air.
Now while I am a bit prejudiced (as an air breather) it is still true that thinking requiers a huge amount of concentrated energy on a continouus basis...We weigh from 110-250 lbs as adults but most of the energy in our large bodies is used by our brains.
On earth, and likley all other water planets, oxygen is the only wide spread oxydizer availible to produce the high power requierments of thinking.
Air has just over 20% oxygen
Water has just under 2% oxygen
You do the math
All inelligent water animals currently known are air breathing and evolved on land only to return to the ocean later.
In future what? Did you mean "in future posts" or perhaps even "in the future"?
I might be wrong, and if that is the case I thank you in advance for pointing out my ignorance.
This space up for sale.
If there are lots of rocky, earth-sized planets in habitable zones, that eliminates many of the simple answers to the Fermi paradox. The alternatives get less and less pleasant from there on.
Think of all the stargates ...
On first blush your theory is sound however you forgot one major things...
STABILITY
Chaos theory (as proven by the biodome) dictates that the larger the system the more stable. A small world will be subject to remarkable swings which would rapidly lead to every single one being unihabitable without constant educated human intervention.
Next the real estate you are describing per cylinder is larger than most countries. The US is remarkably stable but even we had a civil war within 100 years of formation not to mention wars with other countries. Any disruption in the societies ability to maintain the system will result in the cylinder dying very quickly.
Personally I think they are a great idea for asteroids etc but not for the planets. Planets are remarkably stable (even mars and venus once teraformed would be fairly stable) since they are point masses (spheres) with an external energy source. They are much more likely to survive humanity than any man made tube.
Remember, monoculture anything is bad...we want planets and your tubes and maybe ocupied deep space comets and other solar systems etc. The more variety the better.
To quote Churchill: "That is behavior up with which I will not put."
(the quote appears with several slight variations but here is the essence of it)
This space up for sale.
hmmm..
i think you got it wrong.
it is indeed our galaxy. what you meant is our solar system. the article doesn't mention our solar system...
"And" implies a decimal point. 110 is "one hundred ten", 110.3 is "one hundred ten and three tenths".
Statistics? Based on what sample size... what probability? How can you claim the Universe dictates there are other 'Earths' out there based on statistics? :\
I would imagine it is certainly more likely than zero and I understand where you're coming from, but "certainly more likely than zero" is hardly mathematical proof. You say it with such factual certainty that is sort of a disservice to people. I would make it sound more like an assumption than throwing it out there as an indisputable truth. So yes, I have to say NO, it isn't statistically imperative - not YET at least - until we can calculate and express the entire Universe and its events as mathematical formulas... And I don't ever see that happening. In short, it's wrong to assume more Earths HAVE to be out there... It sounds likely because the Universe is (for most human purposes) infinite, but sounding like and being unavoidably certain are two different things.
Fact: Everything I say is fiction.
'Hundreds of Worlds' in Milky Way
No, millions at minimum in the Milky Way, if I'm reading the article properly. The phrase "hundreds of worlds" referred to the outskirts of our own solar system, not the Milky Way galaxy.
When all you have is a hammer, everything looks like a skull.
doh!! *bang head on desk**
German isn't the root language for English any more than Italian is the root language for Spanish. They've been separate for a long damn time.
Just because it's common doesn't make it correct.
I beg to differ. If the society at large has "decided" more or less to drop certain words, its prefectly valid. We decide how language evolves by how we use it, not because some dork in glasses says "no you can't do that, see this rule written here!!"
Mormons knew this already. When they die, they get a world of their very own. The reason they take multiple wives is because they have to populate the entire world by themselves.
The most charitable interpretation of of your comment that I can stomach is that you mean "root language" in a non-standard way. Anything else would be wholly ignorant of basic historical and linguistic facts.
Where I come from (i.e., in linguistics), English is regularly referred to as a Germanic language. In English literature courses, professors in the know will tell you that, while most of our long words come from Latin through French, the short words and the structure are derived from German. There are divergences - e.g., in German one can say Einen Brief schreibt er seiner Mutter but not the word-for-word English version A letter writes he his mother - but they're accounted for and often accompanied by complementary changes elsewhere in the language. The very history of the development of the English language and people points to the influence of German (despite what this guy apparently thinks).
To me, all of this says "root language." Mere temporal separation isn't enough to remove that relation, as you seem to suggest. Beyond that, I have no clue what you seem to mean by the same phrase, so I won't hazard a guess.
So you can laugh all you want to...
I did not know the octopus spent some time on land in its evolutionary history!
In any case, water has the advantage of bouyancy, allowing for the easier growth of larger structures, so there is some advantage to be had there, too.
I'd be much more concerned about the difficulties in creating fire or some high powered energy source, processing ores to get material (much of technological advancement is actually materials science), and imagine the difficulties in exploring electricity both underwater and metal-scarce.
Of course, they may become massive geniuses in ceramics and pottery and the like, so who knows where that would lead?
(-1: Post disagrees with my already-settled worldview) is not a valid mod option.
Compared to a even mouse, an octopus is rather dim. Compared to all other non-mammalian marine life and many reptiles, yes Octopi are rather bright, but it is still a low bar.
As far as bouancy goes, with brains it isn't really size that matters, it's energy. We are significantly smarter than a Sperm Whale but a Sperm whales brain weighs more than our entier body. It is more about energy usage than size. Again that mouse is smarter because it can use the free energy it has to think much more effectivly than you octopus.
As far as tool use, I am personally less concerned. This is mainly due to the fact that once you acheive reasonable intelligence you can figure out / discover how to make better tools. But if you are non-sentient you can't "figure out" how to be sentient.
In the end we must remember that intelligence is actually almost always an evolutionary dead-end. It takes a huge amount of energy and time to develop and most species can do fine with significantly less.
"Just because it's common doesn't make it correct."
No, it does. Linguistics is descriptive, not prescriptive.
May the source be with you.
No, if you RTFA the summary was quite correct. The Oort cloud is a vast place and we don't know exactly what may be lurking there waiting for us to catch a glimpse of it. We can rule out any large bodies closer than a little past Pluto, but something the size of Earth could hide well beyond 1000 AU quite easily. The Oort cloud is proposed to extend between 20,000 AU and 200,000 AU. Given the little bit of research I personally did on terrestrial planet formation and evolution of accretion disks I think it is extremely unlikely something that large would form out there, but there could easily be dozens to hundreds of Pluto sized objects out there waiting to be found.
Isn't it every few months that we see a "there may be more ___ in the universe than we previously thought" article (and Earth-like planets fill that blank every third article)? I say there are more scientists reusing previous work than we previously thought.
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1. To know some German is always useful, that's true.
2. German is not the "root language" of English. Their most recent common ancestor seems to be West-germanic, but let us not delve into that.
3. Not all arguments to the verb write is in the dative case. If that were really so, there would be no need to overspecify with case-markers and prepositions. The truth is that the verb takes arguments from a variety of cases. Since the English surface form of a verb most often do not specify grammatical case you have to do it some other way. That other way is most often by use of prepositions.
However in some cases, there's in no doubt of the arguments grammatical case. If that is so you can safely leave out prepositions and such.
4. English doesn't work the same as German, never has, and propably never will. Oh, there are some glaring similarities, nothing more, nothing less. Now start reading the fourth item again!
let's just pray that there's intelligent life out on one of these planets, because there's bugger all here.
Blazing Spiders
So you can laugh all you want to...
That is complete nonsense.
If robots are sophisticated enough then why do you need to send human embryos?
He wants to colonize the galaxy with Humans, not robots?
The bigger problem is going to be that by time they get there, they will be instructed in a human ethos perhaps hundreds of years old - and will embarrass the heck out of the rest of us.
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
brain-to-finger-misfunction...
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
Just off the top of my head:
I give you the redundancy aspect, but I doubt that'll satisfy the people who suddenly find themselves shooting out a hole or floating in the air or what have you.
......Our galaxy *should* be littered by millions of civilizations........
/.er has the time to do a rough estimate what the probability is that only these factors be met. There surely are other factors not mentioned above.
Carbon is the only central element we know of that can make the extremely complex molecular constructs we find in living things. A "rock" like ours has to have a minimum set of specifications in order to have life capable of anything we could call "civilization".
1.0 One major requirement that this rock must have no other star closer than about 3.8 light years besides its "sun". Another sun sized star closer than about 3.8 light years would mess up that rock's orbit and make the long term climate there inhospitable to life. Only about half of all the stars in the whole universe qualify on this distance specification.
2.0 The gravity at the surface of the planet must be right. Too strong gravity causes the atmosphere to contain too much methane and ammonia, both very poisonous to life. It also makes it hard to move, especially flight. Too little gravity will produce a planet like Mars with little air and water.
3.0 The mass of that star has to be just right. Too large a star would causes its energy output vary more than living things could stand. The energy output of huge stars is not stable, long term. Any life would be exterminated by cooking or freezing before it could get very far along. A too tiny star would force that rock to be too close to its star to get enough heat for life. This would mess up the rotation time, tending to make a day and a year about the same length, such as the planet Mercury. Also there would be excessive tidal forces that would be hard on higher civilized life.
5.0 The rotation time of such a rock could not be too different from that of our earth. If that rock rotates more slowly, then everything would freeze solid every night and cook during the day. A faster spin would make for terrific storms in the atmosphere all the time, preventing the formation of higher civilized society. The rotational speed of Saturn and Jupiter are very high and the winds in its atmosphere are phenomenal. (hundreds of miles per hour)
6.0 Ratio of oxygen and nitrogen in the atmosphere is critical. Too much oxygen would make life functions run too fast and allow any fires to burn whole continents over in devastating fire storms. Too little oxygen would not allow much meaningful activity, because life processes would proceed too slowly. Any other gases, if present in more than trace amounts could also prevent the development of life.
7.0 The crust (outer solid layer) of such a rock has to be the right thickness. If it were too thick, most of the oxygen in the atmosphere would be tied up in it, leaving too little free for living things. Too thin a crust would result in too many severe earthquakes and volcanoes would make it quite difficult to develop any advanced civilization. The crust of our own rock is thinner than the skin on an onion at the relative scale.
8.0 The chemical binding energies of carbon dictate the wavelengths of light needed by living things (photosynthesis in plants on our own rock) that convert the light from the star into a suitable form to knit hydrogen, oxygen, nitrogen, carbon and other elements together as building blocks and fuel for all life forms. The spectrum of that rock's star must therefore be pretty close to that of our sun. Blue or red giants or dwarfs need not apply for the job.
Conclusion: To get a suitable rock upon which a civilization can develop and flourish requires a number of fortuitous "coincidences". On a random basis, this makes the chance of another rock like ours very small. Maybe some enterprising
All theory is gray
Today, children receive next to no education in the field of astronomy. Were they to have a proper understanding of what lies beyond Pluto, they'd probably grow up to realize how silly it is to believe that there is only one planet like Earth.
Considering that there is more money dumped into the athletic arena in schools or bible thumpers believing the Earth is 5,000 years old, I wouldn't be surprised at all if children today even know that there are other planets besides Earth.
.....The Oort cloud is proposed to extend......
The only one minor problem is that nobody has seen any evidence for this fictional construct, nor of dark matter/energy nor black holes. These are structures all necessitated to try and make the newer data from modern space probes fit currently "accepted" theories.
Why doesn't it occur to more scientists to re-examine the assumptions current theories are built on? Current cosmology seems to be like a house of cards, a religion pretending to be science, built on some unproven and perhaps unprovable fundamental assumptions (beliefs). Any theory can only be as valid as the underlying assumptions made. Beautiful equations can all make perfect mathematical and logical sense, but have no relation to physical reality.
All theory is gray
This is why we keep launching infrared, ultraviolet and X-ray observatories, and why the ground is littered with giant radio dishes.
Real Daleks don't climb stairs - they level the building.
"latter" ? surely we can assume you will help yourself of of' this rock any given, /looks at clock/, today, right ?
Unless I just fed the troll, that is.
"Total destruction the only solution" - Bob Marley
I like Clarke but doesnt take much imagination to consider he is talking about our sort of civilization and an underwater one might not need fire.
Have a look here: http://en.wikipedia.org/wiki/American_and_British_English_differences#Numbers
I don't live in England.
The Oort cloud was proposed based on calculating the orbital parameters of known and previously unknown long-period comets. They have to come from somewhere, and if you calculate the orbits they are in you get aphelion distances of 20,000-200,000 AU. Based on their observed frequency and distribution of orbital parameters you can make an estimate of how many would have to be out there to fit the observations. Turns out that it's a lot of them. Based on this, I don't see how the Oort cloud is in any way "fictional" and it certainly wasn't invented to fit any current theories of planet formation. It's really not much different from how we know the Kuiper Belt exists, except recently technology improved sufficiently to gather many more observations of KBOs and confirm its existence beyond any doubt.
.....Current cosmology (e.g. big bang theory)......
Back in 1929 Edwin Hubble discovered the red shift. This is a real observed measurement. However then Hubble , and he was actually cautious, INTERPRETED the cause thereof to be motion and distance. Most of today's cosmology , including the logical inference from this, of the big bang is based on this assumption (belief). To fit many current observations into this interpretation it is necessary to postulate dark matter/energy, black holes, Oort cloud and other things we do not physically observe. We may CALCULATE things, logically and correctly, but we do not OBSERVE them.
All these constructs are logical, mathematical conjectures needed to fit the often puzzling data coming from modern space probes, into the theories built upon this assumption. Another basic assumption is that things in the universe and in nature as a whole, change slowly, predictably, over unimaginably long periods of time. Sudden, unpredictable events in nature, whether here on Earth or billions of light years distant, make us very uneasy. Yet we see past evidence of massive, sudden paradigm changing events, both out in the distant universe and sometimes, to our consternation, right here at home.
It is generally assumed (believed) that stars such as our sun are energized by thermonuclear fusion. From fusion experiments and calculations, we know that such fusion produces copious numbers of neutrinos. Particle physicists have built sophisticate detectors for these in deep underground cavern. The problem is that the number of these neutrinos from the sun is far too small if the sun really gets its energy from fusion. Also, we know that heat always flows from a hotter to a cooler area. Since fusion needs about 20 million deg. C to work, the interior of the sun must be at least that hot. Scientists have observed that the surface of the sun is about 6000 deg. Now here is the puzzler: If heat flows from hotter to colder, why is the corona, the outer atmosphere of the sun at about 3 million degrees? Either the laws of thermodynamics are being violated somehow, or the source of the sun's energy does NOT come from fusion deep inside.
When assumptions are made, it is imperative to re-examine these assumptions, if conflicting and puzzling data comes our way. If the red shift is NOT due to the doppler effect, then the whole big bang theory, with all of its mathematical beauty, collapses. That is not a palatable option that many are willing to consider.
All theory is gray
.....The Oort cloud was proposed based on calculating.......
Well calculating is a fine exercise and may even useful too, if in the end the calculations are corroborated by real, actual physical observations and experiments. That's what makes Einstein's calculations valuable, they are borne out, sometimes spectacularly, by numerous experiments. The best calculation based theories make predictions that can be verified by experiment or observations. That is science. In the absence of such verification, such theories are logical, sometimes even beautiful math, appreciated by mathematicians. Mathematics is NOT science.
Below is an excerpt from Wikipedia concerning the Oort cloud.
"Although no confirmed direct observations of the Oort cloud have been made, astronomers believe it to be the source of all long period and Halley-type comets entering the inner solar system"
Since there is no observation, but only something that astronomers believe. is that science? I'd call what I believe religion or philosophy, but not science. A belief based on fancy math is still only a belief.
Much of today's cosmology is based on mathematically founded beliefs, with no observations or experiments to back up the math.
All theory is gray
Neither do I.
Notmysig