Credit: NASA
One important questions is: what will we find if we do make the effort to go into space? Is there alien life out there, or are we alone in the universe?
We believe that life arose spontaneously on the Earth. So it must be possible for life to appear on other suitable planets, of which there seem to be a large number in the galaxy.
But we don't know how life first appeared. The probability of something as complicated as a DNA molecule being formed by random collisions of atoms in ocean seems incredibly small. However, there might have been some simpler macromolecule which was a building block for DNA or another molecule capable of reproducing itself.
Even if the probability of life spontaneously appearing on a suitable planet is very small, since the universe is infinite, life most likely would have appeared somewhere else too. If the probability is very low, the distance between two independent occurrences of life could be very large.
However, there is a theory known as panspermia, which suggests that life could spread from planet to planet or from stellar system to stellar system carried on meteors. We know that Earth has been hit by meteors that came from Mars, and others may have come from further afield. We have no evidence that any meteors carried life, but it remains a possibility.
An important feature of life spread by panspermia is that, at least in the neighbourhood of Earth, it would also have DNA as its basis. On the other hand, an independent occurrence of life would be extremely unlikely to be DNA-based.
One piece of observational evidence on the probability of life appearing is that we have fossils from 3.5 billion years ago. The Earth was formed 4.6 billion years ago and was probably too hot for about the first half-billion years or so. So life appeared on Earth within half-a-billion years of it being possible, which is short compared to the 10-billion-year lifetime of an Earth-like planet.
This fact would suggest either panspermia or that the probability of life appearing independently is reasonably high. If it the probability very low, one would have expected it to take most of the 10 billion years available.
While there may be primitive life in another region of the galaxy, there don't seem to be any advanced intelligent beings. We don't appear to have been visited by aliens. I am discounting reports of UFOs, of course – my main reason for this being, why would they appear only to cranks and weirdos?
If there is a government conspiracy to suppress the reports and keep for itself the scientific knowledge the aliens bring, it seems to have been a singularly ineffective policy so far.
Furthermore, despite an extensive search by the SETI project, we haven't heard any alien television quiz shows. This probably indicates that there are no alien civilisations at our stage of development within the radius of a few hundred light-years. Issuing an insurance policy against abduction by aliens seems a pretty safe bet.
And why haven't we heard from anyone out there? One view is expressed a Calvin and Hobbes cartoon. The caption reads: "Sometimes I think that the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us."
More seriously, though, there could be three possible explanations of why we haven't heard from aliens. First, it may be that the probability of primitive life appearing on a suitable planet is very low.
Second, the probability of primitive life appearing may be reasonably high, but the probability of that life developing intelligence like ours may be very low.
Just because evolution led to intelligence in our case, we shouldn't assume that intelligence is an inevitable consequence of Darwinian natural selection. It is not clear that intelligence confers a long-term survival advantage. Bacteria and insects will survive quite happily even if our so-called intelligence leads us to destroy ourselves.
There is a third possibility. Life appears, and in some cases develops into intelligent beings, but when it reaches a stage of sending radio signals, it will also have the technology to make nuclear bombs and other weapons of mass destruction. It will, therefore, be in danger of destroying itself before long.
Let's hope this is not the reason we have not heard from anyone. Personally, I favour the second possibility; that primitive life is relatively common, but that intelligent life is very rare. Some would even say it has yet to occur on Earth.
what a nut!
this nutjob lives off the state,he will never speak truth to power because his kind live on the state teat.all this space travel will be paid for by the state in the form of taxes stolen from you by the barrel of a gun.these nutty professors need to get real jobs and quit wasting our time and money on this shite.
Your a nut!
Steven Hawking is a genius. He is thinking in the long term.. I don't think taxes are fair but whats 1/4 percent of our GDP. I'm sure we could take it from our defense budget and do just fine. How about bring all the troops home for every country in the world. That would equal the money we need plus some. Also what he's trying to tell you is that this "new space race" could help mankind. This is how new technology is created. Its a goal. In the long term it could benefit mankind. Just look at the computer you are using and the internet. This is what science has provided for you! You need to wake up and realize that science and research is something we should be spending our money on. Not wars and bailouts. Want to debate more? AIM steve196982
Don't think taxes are fair?
Hahah. So how are you planning on paying for your roads? Airports? Regulatory bodies? Power? Water? Defense?
We need government.
Don't feed this troll
Hmmm...this poster is probably a tin-foil-hat-wearing conspiracy-theorist offended by Prof Hawking's denigration of ufo believers as "cranks" and "weirdos"....just a thought.
I am no fan of big
I am no fan of big governments and repression and all, but I do say these lunatics whining about taxes being taken at the barrel of a gun will be the death of us all. What do they propose? Every large number of people will need government and policing and collective infrastructure. If you don't have collective governmental programs and investments and tax you live in a country like Somalia - where there's is nothing except warlords.
Nut job?
Perhaps...but then most of those 'what brought us to this dance' were or are. Hawking is simply stating what most of us that lived through the shut down of the NASA moon ventures said at the time.
Now, here we are, 35 years later, more than 6 trillion poured into the failed 'great society' with the same percentage of poor now that we had then, and believing that had we not changed direction in this country we would have a well established moon colony today and probably reaching out with manned missions to Mars.
Shalom Freedman
Its encouraging that Stephen Hawking is concerned about the future of the human race, and is not of the party of the 'trans-humanists' or those who believe the 'Singularity' is going to lead to our replacement by a more advanced kind of Intelligence. I also suspect that should we not bring disaster upon ourselves in the coming years mankind will move into space. It seems to me that humanity by its very nature seeks challenge and adventure, new worlds of exploration and creation. And the vast universe lies out there if not like a dream, than at last like a rough and rugged frontier which may give in time new worlds.
Looking in, then out
If you really want humans to go to other star systems, you may need to re-engineer humans either so they can survive on minimal provisions and oxygen (and won't get bored) or develop clones that "hatch" when the ship approaches the target, receive training and then head out. Perhaps space travel starts with the human genome.
SETI's findings
The astronomers who are engaged in the search for extraterrestrial intelligence (SETI) certainly don't believe that the project has failed as this article implies. The truth is that SETI has been impeded for a number of reasons--cost, limited telescope time, and the vastness of the universe.
In the past, most SETI searches have relied on existing radio telescopes. While this allows searches to be conducted on large instruments such as the mammoth 305 m Arecibo dish in Puerto Rico, the amount of telescope time available is necessarily restricted.
Now SETI has a brand new tool--the Allen Telescope Array. This instrument will allow a targeted SETI search to proceed 24 hours a day, 7 days a week.
I hope that everyone reading this article (and Dr. Hawking) will not prematurely designate SETI a failure. The search for ET is really just beginning.
Ellen Jackson, author
THE MYSTERIOUS UNIVERSE
LOOKING FOR LIFE IN THE UNIVERSE
Columbus/Space analogy
I don't dispute the argument that we should push into space. I do take issue with the analogy between Columbus and Space exploration. Columbus and and his backers had the objective of finding a route to India. They knew it existed. The risk was technological, not existential. Space exploration carries the additional existential risk that there is no other place that will sustain human life without cost far in excess of any surplus that could be gained. This is a problem. Thanks.