Where ever we look we seem to be finding planets galore. By the end of this we will probably know of thousands of planets in this galaxy.
We really need bigger telescopes so that we can see them directly.
While the Kepler mission turns up its ever-growing crop of exoplanets, a group of astronomers has announced an exciting find closer to home: looking towards Scorpius, there’s a super-Earth-sized planet just 22 light-years distant, with a habitable-zone orbit. Planets with the right orbit offer the best chance of harbouring …
We can begin to guess how many stars there are in our galaxy. We can begin to guess how many galaxies there are in the universe. The numbers are just huge. Incomprehensibly huge. Science is now starting to find planets on many stars. As science progresses I suspect it will become rarer to find stars without planets.
Given all of that doesn't it seem like arrogance of the highest order to suggest that ours is the only one with life, and that it was put here by some omnipotent power who chose our piddly little insignificant planet out of all those available?
to assume that we are not alone (I hope we're not btw), as we still don't know how (and thus how likely it is) life starts. The universe is very big, but very big and infinite are NOT the same thing.
Besides, as the late Carl Sagan pointed out, somebody has to be first. It could be us.
I expect to get lots of downvotes from those who believe we're not alone simply because they want to believe it. They're very similar to God-botherers in that respect.
We know that complex organics form readily; look at Titan and Enceladus for that. We also know that in an aqueous environment featuring complex organics and energy input that more complex molecules tend to form. We also know that the first Archaea appeared when the Earth had barely cooled; based on that single data point we can state with reasonable odds that the simplest chemistry of life happening in the lifetime of a planet is not a trillions-and-trillions against chance.
And given that last estimation, and the increasing odds that there are trillions and trillions of planets, we can conclude with decent odds there is, at least, simple life somewhere else.
That of course tells us nothing about the existence of advanced sentient species; we may well be the first of those to exist, at least within our light-cone.
Ah! Fermi's paradox and the Drake equation,
Fermi's paradox: If there are so many intelligent communicating civilisations in the galaxy where are they and why haven't they made contact?
Drake’s equation: The number intelligent communicating civilisations in the galaxy. Depending on the assumptions you make, some where between 20,000 and 'less that 1'.
"We can begin to guess how many stars there are in our galaxy."
It's a bit more than a guess, the galaxy is 100,000 - 120,000 light-years in diameter, about 1000 light years 'thick' and contains 200 - 400 billion stars.
"We can begin to guess how many galaxies there are in the universe".
Probably not relevant given the distances involved, The andromeda galaxy is approx 2.7 million light-years from earth, and is approaching us at about 120 kilometres per second and will collide with our galaxy in about 4.5 billion years time.
"The numbers are just huge. Incomprehensibly huge".
"Given all of that doesn't it seem like arrogance of the highest order to suggest that ours is the only one with life"
No. If you take the optimistic figure of 20,000 civilizations in the galaxy then the nearest one is about 350 light years away .
 721,546,273.66 furlongs per fortnight
Theists and atheists agree that there is an omnipotent power that caused our origin and controls our destiny. The former call this "God" or other semi-equivalent terms of varying (and sometimes ambiguous) plurality, and the latter diverge in the nature of their arguments but prefer describing this as causality, gravity, physics, chaos theory, repetitive randomness creating all possibilities, free will, and P!=NP.
As sects of theists bicker about their origin myths and the nature and name of the higher power, so do atheist sects bicker about their origin theories and the name and nature of our causation.
I suppose the difference is that the former irrationally ascribe to this power a motivation that relates specifically to Men. The latter irrationally deny motivation without evidence for such denial of willful causation - which is equally a matter of unproven Faith.
It has become unacceptable to say "I don't know." That's a shame because acknowledgement of your ignorance is a prerequisite to learning. There are many things to learn yet that we must let go of this dichotomy to know. Some of these paths may actually lead to a proof or disproof of Motive, of measuring and understanding the nature of the Motive if it exists. But we have to get past this fight to discover that.
Maybe this is a test of our Faith, or of our Reason, or our ability to Hope without reason. Possibly all three, as the Universe has many dimensions.
Having now offended every single person who might read this I can only hope to achieve the most thumbs-down of any Theregister comment ever. I suppose that would be an achievement of sorts. Is there a badge for that?
Gravity is proportional to mass, which at a fixed density goes as volume. Volume goes as the cube of the radius. Gravity is inversely proportional to the square of the distance from the center of the planet. So combining terms, gravity goes up linearly with radius, or as the cube root of mass.
In the case of a planet with 4.5 times the Earth's mass and the same density, then the surface gravity would be (4.5)^(1/3) = 1.65 times ours. Since the parent star is "metal poor" (astronomers call anything above Helium on the periodic table a metal), this planet is likely to have less iron core and heavy rock mantle, and more lightweight elements, We will have to wait for better telescopes to be sure what it's made of.
In the context of stars, a "dwarf" is a general term covering all sorts of small stars, whether brown (not big enough to actually even be a star), red (significantly smaller than our own, mostly red, and never going to the red-giant phase), yellow (similar to our own Sun), orange (smaller, more orange-looking), white (post-red-giant super-hot cinder, basically), or black (white dwarf that's cooled far enough to not emit meaningful amounts of light).
So we orbit a yellow dwarf, and this planet they've just found orbits an M-class (i.e. red) dwarf.
Black dwarf stars are a largely theoretical concept, as the universe isn't old enough for a white dwarf to have cooled enough to become a black dwarf.
Also theoretical are blue dwarfs which should be the later stages of red dwarfs but since red dwarfs burn so slowly no star has got anywhere near the blue dwarf stage.
Great isn't it :)
Also, I have a nagging feeling that planets in the liquid water area around red dwarfs would have significant problems for some reason (probably related to the proximity to the star), but I can't remember what it was. Shall I be arsed to Google or shall I wait for one of our boffin-minded commentors to fill in my blanks?
What is it about water that gets scientists saying that we can only have life when we have water available. I know it seems quite a useful substance but has anyone considered that we could possibly have life without water?
Maybe I am being stupid so I am heading behind a mask of ignorance.
Not a stupid question.
But how you search for other types of life forms when you got nothing to compare it so, no signatures to compare.
Looking for life out their that resemble the life on Earth is easier with today's technology than looking life with an unknown signature.
It fairly easy for scientist to detect water and methane for example.
Feel free to challenge some of the assumptions in what follows, but I think you'll find that they are all quite reasonable.
Life needs cells, both to get started in the first place and to specialize and compartmentalise functions in higher life-forms. It's hard to imagine anything complex enough to feed and reproduce that isn't organised out of some basic building block like a cell.
Cells need to be basically a drop of liquid enclosed in a membrane. It needs to be liquid to allow the flow of nutrients to and from interesting things like macromolecules. (It also needs to be a fairly good solvent for that purpose.) It needs to be enclosed to allow concentrations of those things to grow to interesting levels and concentrations of waste products to be expelled and kept out.
That liquid will be needed in large quantities. If it requires rare elements or complicated chemistry to produce it, it won't ever be present in large enough quantities to kick-start evolution.
Life also needs the right temperature range, which is one that is never so cold as to stop the interesting chemistry and never so hot as to destroy the delicate structures. This requires a balance between the available thermal energy and the typical energy of chemical bonds, both of which are determined by basic physics. The range may be fairly broad, but it is going to be the same range across the whole universe.
So a pre-requisite of "life as we know it" is a cheap material that is liquid at the right temperature. Water is probably the only substance known that fits the bill. Also, most molecules as simple as water are gases at room temperature. Water is only liquid at room temperature because of a happy accident of hydrogen bonding, so it is quite probable that it is the *only* suitable substance.
So a pre-requisite of "life as we know it" is a cheap material that is liquid at the right temperature. Water is probably the only substance known that fits the bill.
What about pressure? On a large mass planet with a thick atmosphere might you not, within a temperature scope that could support cellular organisms, have a different range of liquid chemicals? And bacteria can survive in some pretty harsh environments - including high pressure, high temperature environments (around thermal vents in ocean trenches for instance).
Granted, it wouldn't even be a nice place to visit, let alone live, but wouldn't it be possible?
Water is a remarkable liquid. It's a solvent that dissolves all sorts of other chemicals. Effectively these are different varieties of water. Maybe there are other simple molecules with amazing properties of versatility which chemistry could be based on. Hydrocarbons for instance, but these are thought to have been created by life rather than chemistry. They are used as signs of life.
I think the conditions for life are far more narrow. It would not surprise me if this was the only planet were conditions were just right. To recreate our conditions by chance would involve the combination of so many variables as to the universe not being big enough to hold them all.
For instance if there were 100 variables that all had to be within 1% for life to kick off then that would be a chance of 1 in 10^200
However if it was that easy then they would have made life in the lab by now.
How hard is it to make an iPad? Probably need better than 1% tolerances on more than 100 things. You don't make one of those by chance.
We have a planet, likely to be as warm as Earth, in the right zone for water and whatnot. Not much light though... so I'd guess that a nice intelligent efficient species would evolve, with big dark eyes, and a skin tone suited to absorbing infra-red. Sounds just like every alien in every movie up to about the year 2000.
Also - as a vegetarian I feel I must ask - how long do you think it will be before people decide that those supergiant shrimp they found should be fished for food?
But that's at 0.25c; whereas the fastest vehicle ever made by humans was probably the Galileo probe that entered the atmosphere of (crashed into) Jupiter at about 106,900 mph. At that speed (0.00016c) it would take 137,500 years to reach GJ 667C.
Remember what the HHGTTG says: "Space," it says, "is big. Really big. You just won't believe how vastly, hugely, mindbogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space, listen..."
I suggest that if it were important, it would not be too hard to develop a vehicle that could deliver a small probe to a planet 22 light years away in less that 100 years. It wouldn't take very long under a level of continuous acceleration currently achievable to reach 0.25c or faster.
The first hard part would be getting that much fuel into Earth orbit, but maybe a nuclear heater and a big block of something like CO2 or ice could be made to work.
The second hard part would be steering the probe when it got there - I guess it would have to be autonomous enough to find the planet and land (crash gently).
At least the 'Got Here' message would only take 22 years to get to us...
Surely it could only accelerate continuously for the first half of the trip, and then it would need to decelerate continuously for the other half. Otherwise it would arrive in the target system at 0.25c and fly straight through it in a matter of (hours/days/weeks?), not giving it much chance to do much discovering of stuff...
Also, what if it meets something on the way, going at 0.25c? Even the smallest bit of interstellar dust or ice is not going to leave much spacecraft left.
...so speeding up and slowing down are both accelerations in the language of physics.
As far as collisions, yes, dust particles hitting the leading edge at relativistic speeds would emit X rays or gamma rays, and a good sized rock would make a big explosion. You would need a really serious shield.
Why not use your fuel? If you have a fusion motor, your fuel could be a huge ball of ice. If you basically have a cue-ball of ice for fuel with a fusion ion drive attached to it, you can use the fuel as a debris shield without worries about explosions being catastrophic events.
Plus, you can get lots and lots of water ice already in orbit; capture a cometary nucleus in the outer solar system and Bob's your uncle.
Indeed so, and so any design for getting up into the tenths lightspeed regime must cope with carrying enough fuel to <i>decelerate</i> at journey's-end (unless you just want to send home a few blue-shifted pics as you hurtle past). If you travel halfway with your fuel in front as a shield, you can't just do a quick one-eighty and decelerate for the other half.
Why do I have a vision of a future astronomer hunting for software that can decode a raw CCD image file transmitted from a device that hasn't been manufactured for a hundred and fifty years?
... but you could shut off the engine halfway and then disconnect the engine and reattach it at the front. You could also, in the early stages of the flight, excavate fuel from the cometary nucleus such that the instrument package is buried deep inside; and the fuel would be removed from the aft end to maintain as much shielding as is feasible for the high-speed part of the journey. The goal would be, upon arrival, to have a slender chunk of fuel left over (reinforced by fuel delivery tubes), with the engine at the fore end and the now-uncovered instruments aft. There is really nothing that could be done to absolutely protect the engines in the deceleration phase of flight; there would have to be enough small-ish engines that redundancy could handle the loss of a few from collisions whose damage can't be repaired.
 You would actually continue positive acceleration past the exact midway point, since the decreasing fuel mass would result in much greater acceleration magnitude at the end of the flight.
"It wouldn't take very long under a level of continuous acceleration currently achievable to reach 0.25c or faster."
No, but it would take a lot of kinetic energy; 0.25c, even with simplified Newtonian calculations, is 2.8 x 10 ^ 15 Joules per kilogram of mass. This is about the same energy as moving an aircraft carrier (100,000 tonnes) at 7,500 m/s. So each kg of vehicle moving at 0.25c is roughly the same as putting the USS Nimitz into Low Earth Orbit.
And this is just the basic energy of the result; factor into this the actual fuel load required to achieve this speed and that you need to accelerate the fuel with the vehicle, with the total mass reducing as the reaction mass is ejected and you actually need a lot more energy. A Saturn 5 burns about 2,000 tonnes of fuel to put a 100 tonne payload into LEO.
Even with VASIMIR at 1,400 MJ per kg of fuel you need 2,000 tonnes of propellant to get enough kinetic energy into 1kg of vehicle; but this doesn't take into account the mass of the propellant, which is also being accelerated along with the vehicle until the point that it is used, so you need to integrate the combined propellant mass/speed to get the full result (I'm supposed to be working so I haven't done this yet). The result will be FUCKING HUGE!!!
I'm afraid basic physics shows that an interstellar probe is really a long way off; the scale of the Universe is just too big for most humans to even conceive, let alone engineer for. (but I'd be happy to see future generations of physicists and engineers try to meet the challenge)
Yeah, we'd all like to see future generations of anybody doing anything at all (almost), but luckily for the future generations, it ain't going to happen.
It will be a problem to sell the idea of a multi-century exploration mission to your Parliament | Senate | Duma | Revolutionary Council [delete as appropriate] because none of us alive and tax-paying now will ever see a whisper of a result. Even more so when one of the great space-exploring nations inexplicably drops an intra-system exploratory vehicle into the Pacific Ocean.
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"Red dwarfs? That's the shitty part of the local neighbourhood.Your probes are likely to be jacked and stripped for parts by local alien minorities."
And that is what mankind will take to the stars. Prejudice. Racism. Hatred. And wait till a local earth boy falls in love with an alien chick and starts banging her... KKK? Evangelical Christians? Fundamentalists? Taliban?
You ain't seen nothing of how truly fucked up mankind is...
Here's hoping that your species never set foot outside your solar system.
Actually, there's very little reason that a biological system couldn't exist on, say, liquid arsenic just as well as water. It would take very little change to DNA for a species to be able to breath Sulpher Dioxide and drink Arsenic.
We look for water primarily because we have proof of water-requiring life-forms, but we should also recognise that we take this proof from a sample of only one. Us.
Indeed. From a historical perspective the ones that aren't poisoned by, nay thrive on dissolved or atmospheric oxygen are a recent innovation. Oxygen molecules floating about the place in reasonable concentration to be reliable didn't really happen until most of the metallic elements in the crust had been oxidised first. Which took quite a long period of biological activity to happen.
@Originone, the Earth may be unusually dense.
As Dani says, a system poor in heavier elements might have lower density planets anyway.
However, since rocky planets at about our orbit will have a very low % of hydrogen and virtually no helium I'm not sure it matters what their ratio is.
As I recall pretty much all the helium on Earth isn't from its formation, but from radioactive decay that happened to occur in places where it could be trapped, thus helium although it's the second most common element in the universe is actually probably rarer than gold on the Earth.
The current consensus is that the Moon was formed by a roughly Mars sized object hitting the Earth and splatting off a good chunk of the outer, lighter layers, leaving the Moon as a relatively less dense object and the Earth denser.
The material didn't come off in a blob. The proto-Earth and the impactor were both substantially vaporized by the energy of the collision which caused a cloud of matter to get flung up into the sky. Over time the stuff that had enough energy to stay up coalesced into a sphere, but it's on a near circular orbit now because that's the average trajectory of the particles it was composed of.
wtf is the point. really. it's a dirt ball. it's too far away to investigate in any viable way, barring a discovery on the unobtainium type, say, a gate that you can steer remotely to within a useable distance.. we're stuck here and all this escapism is an expense we really should divert elsewhere. i can't think of a practical use for this knowledge. Park the program for fifty years and use the cash to sort out something a little closer to home.
I'm all for research spending etc.., just into things that might make this kind of thing viable when it's more of an option. we've a few things to sort out on our own planet first.
Seriously Jelliphiish, no offence but you're an idiot. We, by our very nature, can't help but explore and look around the next corner, over the next horizon. It's part of what makes us human. Pure exploration isn't supposed to lead to any practical use but inevitably it does. This "discovery" adds fuel to the postulation that we are NOT alone in the universe and that we are NOT so damn special. We need an answer to that. We need to know if we're some random 1 a googleplex chance or if there are neighbours out there. It also increases our speculation about the ways planets and systems form and challenges previously held beliefs - god I love science (see what I did there? :) )
Oh, and on the water front (so to speak) any molecular biologists out there that can correct me or in some way fill in the blanks but as far as I remember one of the reasons we say that water is required for life is that as well as the very detailed and excellent explanation of Ken Hagan above; water has certain properties that cause the protein chains to loop round as they are attracted and repelled by the water molecules which enables amieno acids to form and hence DNA. No water, no DNA, no life as we know it. - I could be wrong. It's rare, but it happens.
The good news is that they'll have been watching our TV for the last 40-50 years.
Currently such delights as Bergerac and the Crystal Maze will be hitting their screens, as well as, conincidentally, Red Dwarf. Lucky them.
Presumably they've not been sending us their telly? How selfish! I reckon they could do a good line in "Dark Humour".
all they'll see is 3 different signals (or is there another one for B&W).
they can translate that into whichever frequencies they want.
We'll do the same, It'll be interesting how many different signals they'll send - will they be like dogs and see with fewer receptors? Or squid with far, far more?