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Silence in the sky—but why?
PhysOrg ^ | 8/25/13

Posted on 08/26/2013 4:29:42 PM PDT by LibWhacker

(Phys.org) —Scientists as eminent as Stephen Hawking and Carl Sagan have long believed that humans will one day colonise the universe. But how easy would it be, why would we want to, and why haven't we seen any evidence of other life forms making their own bids for universal domination?

A new paper by Dr Stuart Armstrong and Dr Anders Sandberg from Oxford University's Future of Humanity Institute (FHI) attempts to answer these questions. To be published in the August/September edition of the journal Acta Astronautica, the paper takes as its starting point the Fermi paradox – the discrepancy between the likelihood of intelligent alien life existing and the absence of observational evidence for such an existence.

Dr Armstrong says: 'There are two ways of looking at our paper. The first is as a study of our future – humanity could at some point colonise the universe. The second relates to potential alien species – by showing the relative ease of crossing between galaxies, it makes the lack of evidence for other intelligent life even more puzzling. This worsens the Fermi paradox.'

The paradox, named after the physicist Enrico Fermi, is something of particular interest to the academics at the FHI – a multidisciplinary research unit that enables leading intellects to bring the tools of mathematics, philosophy and science to bear on big-picture questions about humanity and its prospects.

Dr Sandberg explains: 'Why would the FHI care about the Fermi paradox? Well, the silence in the sky is telling us something about the kind of intelligence in the universe. Space isn't full of little green men, and that could tell us a number of things about other intelligent life – it could be very rare, it could be hiding, or it could die out relatively easily. Of course it could also mean it doesn't exist. If humanity is alone in the universe then we have an enormous moral responsibility. As the only intelligence, or perhaps the only conscious minds, we could decide the fate of the entire universe.'

According to Dr Armstrong, one possible explanation for the Fermi paradox is that life destroys itself before it can spread. 'That would mean we are at a higher risk than we might have thought,' he says. 'That's a concern for the future of humanity.'

Dr Sandberg adds: 'Almost any answer to the Fermi paradox gives rise to something uncomfortable. There is also the theory that a lot of planets are at roughly at the same stage – what we call synchronised – in terms of their ability to explore the universe, but personally I don't think that's likely.'

As Dr Armstrong points out, there are Earth-like planets much older than the Earth – in fact most of them are, in many cases by billions of years.

Dr Sandberg says: 'In the early 1990s we thought that perhaps there weren't many planets out there, but now we know that the universe is teeming with planets. We have more planets than we would ever have expected.'

The Acta Astronautica paper looks at just how far and wide a civilisation like humanity could theoretically spread across the universe. Past studies of the Fermi paradox have mainly looked at spreading inside the Milky Way. However, this paper looks at more ambitious expansion.

Dr Sandberg says: 'If we wanted to go to a really remote galaxy to colonise one of these planets, under normal circumstances we would have to send rockets able to decelerate on arrival. But with the universe constantly expanding, the galaxies are moving further and further away, which makes the calculations rather tricky. What we did in the paper was combine a number of mathematical and physical tools to address this issue.'

Dr Armstrong and Dr Sandberg show in the paper that, given certain technological assumptions (such as advanced automation or basic artificial intelligence, capable of self-replication), it would be feasible to construct a Dyson sphere, which would capture the energy of the sun and power a wave of intergalactic colonisation. The process could be initiated on a surprisingly short timescale.

But why would a civilisation want to expand its horizons to other galaxies? Dr Armstrong says: 'One reason for expansion could be that a sub-group wants to do it because it is being oppressed or it is ideologically committed to expansion. In that case you have the problem of the central civilisation, which may want to prevent this type of expansion. The best way of doing that get there first. Pre-emption is perhaps the best reason for expansion.'

Dr Sandberg adds: 'Say a race of slimy space aliens wants to turn the universe into parking lots or advertising space – other species might want to stop that. There could be lots of good reasons for any species to want to expand, even if they don't actually care about colonising or owning the universe.'

He concludes: 'Our key point is that if any civilisation anywhere in the past had wanted to expand, they would have been able to reach an enormous portion of the universe. That makes the Fermi question tougher – by a factor of billions. If intelligent life is rare, it needs to be much rarer than just one civilisation per galaxy. If advanced civilisations all refrain from colonising, this trend must be so strong that not a single one across billions of galaxies and billions of years chose to do it. And so on.

'We still don't know what the answer is, but we know it's more radical than previously expected.'


TOPICS: Astronomy; Science
KEYWORDS: breakthroughlisten; colonization; extraterrestrials; fermi; fermiparadox; paradox; seti; silence; xplanets
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To: Moonman62

You’re taking the conversation off track. No one’s arguing the relative ratios between living organisms and inorganic matter.

Of course you’re correct in your assertion, but that’s not what the discussion was about. We were talking about the possibility that life (in some form) could exist on other worlds, and whether or not worlds with habitats such as ours exist in the known universe.


141 posted on 08/27/2013 11:41:12 AM PDT by Windflier (To anger a conservative, tell him a lie. To anger a liberal, tell him the truth.)
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To: Windflier
You’re taking the conversation off track. No one’s arguing the relative ratios between living organisms and inorganic matter.

You're arguing about it. I put up objective measurements and you only countered with subjective opinions.

If life is rare on Earth and even rarer in the Solar System, it's probably rare everywhere else, too. I wouldn't be surprised if there is primitive life elsewhere, but technological civilizations, I doubt it.

142 posted on 08/27/2013 12:03:50 PM PDT by Moonman62 (The US has become a government with a country, rather than a country with a government.)
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To: NYer

I just caught that one within 3 minutes. You are most welcome NYer, my pleasure! :)


143 posted on 08/27/2013 12:54:17 PM PDT by Berlin_Freeper
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To: DManA; Windflier; FredZarguna

Well, sometimes you gotta have faith as well. It took Edison 2000 or more tries to get his light bulb to work, he had to keep the faith. Dr. Werner von Braun and Robert Goddard tried many times before they got their rockets to work. I’m sure they all had their detractors. Let me add that it was said in the 1890’s where there was thought to close the pantent office because they thought that “all of the things that needed invented were invented.” I think even Albert Einstein would say that despite his research, still you got to keep an open mind for that discovery that could change what we know, or thought, that was true. WE still have many, many pages to write in this book.


144 posted on 08/27/2013 1:25:46 PM PDT by Nowhere Man (It is about time we re-enact Normandy, at the shores of the Potomac.)
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To: Zeneta
Evolutionists, Neo-Darwinists have lost and

So says the Creationist who believes only in the religion was baptized in and who dismisses all other religions and who has never met the God he believes in.

145 posted on 08/27/2013 2:05:36 PM PDT by LoneRangerMassachusetts (The meek shall not inherit the Earth)
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To: Smokin' Joe
Until we can communicate FTL or at least receive transmissions, we won't hear any incoming traffic any more than we'd hear FM radio tuned in to AM.

Actually you can tune in FM signals using AM mode. All you do is tune in the signal and go off frequency a little on either side of the signal. This is called slope detection where because you're off frequency a little, the FM signal is "converted" into AM and thus can be received. It isn't the greatest fidelity but it is readable. I used to pick up the old, old cordless phones from the late 1970's and early 1980's when the base transmitted above the AM band ( in the 1650 - 1750 kc area) to the handset on my old Sanyo RP-8700. The signal was FM but my radio being AM, I was able to do this. I'm an amateur radio operator. Now tuning in AM signals in FM mode doesn't fly too well, I tried to tune in aircraft (they use AM) in the 118 to 137 Mc area using the FM detector in my scanner, didn't work too well. I also have a 1970's Radio Shack Patrolman radio that tunes in VHF-Lo/Hi and UHF-Lo/Hi and I believe the detector is AM although most of those signals are FM. I can tune in the Blue Angels and Thunderbirds that use the 137 - 144 Mc Government band very well and they use AM mode. I remember one airshow, I live near the airport, where the neighborhood turned out to watch the Thunderbirds and I had my old Patrolman on tuning in the planes and the neighbors thought it was a hoot.
146 posted on 08/27/2013 3:39:25 PM PDT by Nowhere Man (It is about time we re-enact Normandy, at the shores of the Potomac.)
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To: Nowhere Man

Edison wasn’t the first to make light from electricity. His work with electric lighting was a pure engineering project. He was a brilliant engineer, manager, and businessman, not a scientist.

von Braun and Goddard could never have accomplished anything if the hadn’t understood the physics. In fact it was that understanding of physics that told them that what they were dreaming about was possible.


147 posted on 08/27/2013 3:53:22 PM PDT by DManA
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Note: this topic is from 8/26/2013. Thanks LibWhacker.
 
X-Planets
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Google news searches: exoplanet · exosolar · extrasolar ·

148 posted on 08/27/2013 8:15:29 PM PDT by SunkenCiv (It's no coincidence that some "conservatives" echo the hard left.)
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In the book "Communication with Extraterrestial Intelligence" (Sagan editor -- CETI was the old acronym) Thomas J Gold ("Deep Life", "Power from the Earth") said "But I am not really willing to accept your premise, because it may well be that the means of communications they have are of a kind that we do not know how to receive, and that they would not have the means of communicating with sufficiently powerful radio or optical signals. That is something which, technologically, is too difficult for them but they would have some other means we would not recognize." (see also 210)



149 posted on 08/27/2013 8:17:28 PM PDT by SunkenCiv (It's no coincidence that some "conservatives" echo the hard left.)
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Comment #150 Removed by Moderator

To: Nowhere Man
I think even Albert Einstein would say that despite his research, still you got to keep an open mind for that discovery that could change what we know, or thought, that was true. WE still have many, many pages to write in this book.

Bingo.

It has been man's quest since time immemorial to unlock the secrets of the material world, and re-structure it to his needs and liking. The quest for understanding and knowledge of our surroundings is an unbroken chain from prehistoric times, to the present. Of course, it will continue.

The future is a vast and endless possibility. It's not even possible to accurately predict the technological advancements of coming eras. What we can predict, is that they will come, and that they'll astound us.

151 posted on 08/27/2013 11:10:04 PM PDT by Windflier (To anger a conservative, tell him a lie. To anger a liberal, tell him the truth.)
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To: Moonman62
If life is rare on Earth and even rarer in the Solar System, it's probably rare everywhere else, too.

But life isn't rare on Earth, and from that, we can reasonably infer that it isn't rare throughout the universe.

You're arguing that the small size of the biomass on our planet in relation to the large size of the geologic mass, means that life is "rare". It's not.

It's ubiquitous throughout the outer layers of our world, and will likely be ubiquitous on the surfaces and oceans of countless other worlds. Some of that life is quite likely to be intelligent, as well.

152 posted on 08/27/2013 11:17:57 PM PDT by Windflier (To anger a conservative, tell him a lie. To anger a liberal, tell him the truth.)
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To: Windflier
You're arguing that the small size of the biomass on our planet in relation to the large size of the geologic mass, means that life is "rare". It's not. It's ubiquitous throughout the outer layers of our world,

What objective measure do you have to back up your claim? If you were to take away the mass of the planet and its gravity, or for that matter the mass of the Sun and its energy, would life exist at all?

153 posted on 08/28/2013 3:49:27 AM PDT by Moonman62 (The US has become a government with a country, rather than a country with a government.)
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To: Moonman62
What objective measure do you have to back up your claim?

Moon, we must have some fundamental misunderstanding going on here. Perhaps it's due to the limitations of text based communication.

I'm not challenging the truth of what you're saying at all. What I'm saying is that you're making a fundamentally different assertion than what I and others here are discussing.

We say that life is ubiquitous on this planet, which is an observable truth that can't seriously be challenged. Life can be found in nearly every place you look on Earth. It has adapted to, exploited, and colonized nearly every environmental niche we've examined - including environments that one would think are far too extreme to harbor life.

Many people think that life may have done the same on other worlds. Scientists already know that some environmental niches on other planets are less extreme than some we find on Earth where life exists.

154 posted on 08/28/2013 9:58:30 AM PDT by Windflier (To anger a conservative, tell him a lie. To anger a liberal, tell him the truth.)
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To: Nowhere Man
What many of the people posting to me are not understanding is that this is not a matter of faith in human ingenuity; nor is it an engineering problem -- which is what all of your examples are.

No one has more faith in the power of the human mind than I do. However, I do not believe that someday we'll overcome the First Law of Thermodynamics if we "just try hard enough." [Nor we will overcome the Second Law of Thermodynamics, the Uncertainty Principle, the Exclusion Principle, ... ]

These are laws of physics, not engineering challenges. The four dimensional space-time we live in has a certain geometry. Trying to overcome that geometry -- which is known in physics as Lorentz Invariance is a waste of time, every bit as much as trying to violate the law of the conservation of energy. The basic laws governing Gauge Bosons [and their classical analogues, like Maxwell's Equations] simply do not work unless the universe is Lorentz Invariant. It's not a matter of being clever or trying hard.

155 posted on 08/29/2013 7:03:02 PM PDT by FredZarguna (CPVPV sounds like a very nasty STD virus. Just saying...)
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To: FredZarguna; Windflier

Who really knows what the future holds, we might discover a new law or way that could make some of what we understand either wrong or amended. It is not the end all or be all. I mean what we know today, to someone in the future, we might be seen the same as we see people who still believe in the Platonic Universe where the sun, stars, planets and so on go around the Earth and that there are only 4 elements, Earth, Wind, Fire and Water. Perhaps there is more to it than just adding a few extra “D” cells to the Warp Drive and a RAM upgrade to the hyperspace computer, but you never say never and have to keep the mind open to other possibilities.


156 posted on 08/29/2013 7:16:08 PM PDT by Nowhere Man (It is about time we re-enact Normandy, at the shores of the Potomac.)
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To: Nowhere Man

OK. I give up. Go invent your perpetual motion machine and get rich.


157 posted on 08/29/2013 7:18:33 PM PDT by FredZarguna (CPVPV sounds like a very nasty STD virus. Just saying...)
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To: Nowhere Man
...you never say never and have to keep the mind open to other possibilities.

Advancement in the material sciences has continued since prehistoric times, when man first learned to use a stick to dig for grubs, to the present, where we regularly send men and high tech devices into space.

We've climbed a long stair to where we are today, but we're certainly not at the top landing by any means. We can't even see the top landing from our current vantage point. There's much, much more to be discovered about the universe. More than we here today can possibly imagine.

158 posted on 08/29/2013 7:33:37 PM PDT by Windflier (To anger a conservative, tell him a lie. To anger a liberal, tell him the truth.)
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To: Windflier

” Advancement in the material sciences has continued since prehistoric times, when man first learned to use a stick to dig for grubs, to the present, where we regularly send men and high tech devices into space.

We’ve climbed a long stair to where we are today, but we’re certainly not at the top landing by any means. We can’t even see the top landing from our current vantage point. There’s much, much more to be discovered about the universe. More than we here today can possibly imagine.”

That was great. I’m putting that in my list of quotes. Well said.


159 posted on 08/29/2013 7:38:42 PM PDT by Lurkina.n.Learnin (If global warming exists I hope it is strong enough to reverse the Big Government snowball)
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To: Lurkina.n.Learnin
I’m putting that in my list of quotes. Well said.

Why, thank you, friend. That's very kind of you.

160 posted on 08/29/2013 8:43:51 PM PDT by Windflier (To anger a conservative, tell him a lie. To anger a liberal, tell him the truth.)
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