IS THERE OTHER INTELLIGENT LIFE IN THE UNIVERSE?

According to the famous scientist Stephen hawking.
He would like to speculate a little on the development of life in the universe, and in particular on the development of intelligent life. He shall take this to include the human race, even though much of its behaviour throughout history has been pretty stupid and not calculated to aid the survival of the species. Two questions we shall discuss are “What is the probability of life existing elsewhere in the universe?” and “How may life develop in the future?”It is a matter of common experience that things get more disordered and chaotic with time. This observation even has its own law, the so-called second law of thermodynamics. This law says that the total amount of disorder, or entropy, in the universe always increases with time. However, the law refers only to the total amount of disorder. The order in one body can increase provided that the amount of disorder inits surroundings increases by a greater amount.This is what happens in a living being. We can define life as an
ordered system that can keep itself going against the tendency todisorder and can reproduce itself. That is, it can make similar, but independent, ordered systems. To do these things, the system must convert energy in some ordered form—like food, sunlight or electricpower—into disordered energy, in the form of heat. In this way, the
system can satisfy the requirement that the total amount of disorder increases while, at the same time, increasing the order in itself and its
offspring. This sounds like parents living in a house which gets messierand messier each time they have a new baby.A living being like you or him usually has two elements: a set of
instructions that tell the system how to keep going and how to reproduce itself, and a mechanism to carry out the instructions. In
biology, these two parts are called genes and metabolism. But it is worth emphasising that there need be nothing bio-logical about them.
For example, a computer virus is a program that will make copies ofitself in the memory of a computer, and will transfer itself to other
computers. Thus it fits the definition of a living system that I havegiven. Like a biological virus, it is a rather degenerate form, because it
contains only instructions or genes, and doesn’t have any metabolism of its own. Instead, it reprograms the metabolism of the host
computer, or cell. Some people have questioned whether virusesshould count as life, because they are parasites, and cannot existindependently of their hosts. But then most forms of life, ourselves
included, are parasites, in that they feed off and depend for theirsurvival on other forms of life. I think computer viruses should countas life. Maybe it says something about human nature that the onlyform of life we have created so far is purely destructive. Talk aboutcreating life in our own image. I shall return to electronic forms of lifelater on.
What we normally think of as “life” is based on chains of carbonatoms, with a few other atoms such as nitrogen or phosphorus. Onecan speculate that one might have life with some other chemical basis,such as silicon, but carbon seems the most favourable case, because it
has the richest chemistry. That carbon atoms should exist at all, withthe properties that they have, requires a fine adjustment of physical
constants, such as the QCD scale, the electric charge and even thedimension of space–time. If these constants had significantly different
values, either the nucleus of the carbon atom would not be stable orthe electrons would collapse in on the nucleus. At first sight, it seems
remarkable that the universe is so finely tuned. Maybe this is evidencethat the universe was specially designed to produce the human race.
However, one has to be careful about such arguments, because of theAnthropic Principle, the idea that our theories about the universe must
be compatible with our own existence. This is based on the self-evidenttruth that if the universe had not been suitable for life we wouldn’t be
asking why it is so finely adjusted. One can apply the AnthropicPrinciple in either its Strong or Weak versions. For the StrongAnthropic Principle, one supposes that there are many different
universes, each with different values of the physical constants. In asmall number, the values will allow the existence of objects like carbon
atoms, which can act as the building blocks of living systems. Since wemust live in one of these universes, we should not be surprised that the
physical constants are finely tuned. If they weren’t, we wouldn’t behere. The Strong form of the Anthropic Principle is thus not very
satisfactory, because what operational meaning can one give to theexistence of all those other universes? And if they are separate from
our own universe, how can what happens in them affect our universe?Instead, I shall adopt what is known as the Weak Anthropic Principle.
That is, he shall take the values of the physical constants as given. But he shall see what conclusions can be drawn from the fact that life exists onthis planet at this stage in the history of the universe.
There was no carbon when the universe began in the Big Bang, about13.8 billion years ago. It was so hot that all the matter would have beenin the form of particles called protons and neutrons. There wouldinitially have been equal numbers of protons and neutrons. However,as the universe expanded, it cooled. About a minute after the Big Bang,the temperature would have fallen to about a billion degrees, about ahundred times the temperature in the Sun. At this temperature,
neutrons start to decay into more protons.
If this had been all that had happened, all the matter in the universewould have ended up as the simplest element, hydrogen, whosenucleus consists of a single proton. However, some of the neutronscollided with protons and stuck together to form the next simplestelement, helium, whose nucleus consists of two protons and twoneutrons. But no heavier elements, like carbon or oxygen, would havebeen formed in the early universe. It is difficult to imagine that one
could build a living system out of just hydrogen and helium—andanyway the early universe was still far too hot for atoms to combine
into molecules.The universe continued to expand and cool. But some regions hadslightly higher densities than others and the gravitational attraction ofthe extra matter in those regions slowed down their expansion, andeventually stopped it. Instead, they collapsed to form galaxies andstars, starting from about two billion years after the Big Bang. Some ofthe early stars would have been more massive than our Sun; theywould have been hotter than the Sun and would have burned theoriginal hydrogen and helium into heavier elements, such as carbon,
oxygen and iron. This could have taken only a few hundred millionyears. After that, some of the stars exploded as supernova andscattered the heavy elements back into space, to form the raw materialfor later generations of stars.
Other stars are too far away for us to be able to see directly if theyhave planets going round them. However, there are two techniquesthat have enabled us to discover planets around other stars. The first isto look at the star and see if the amount of light coming from it isconstant. If a planet moves in front of the star, the light from the starwill be slightly obscured. The star will dim a little bit. If this happens regularly, it is because a planet’s orbit is taking it in front of the star
repeatedly. A second method is to measure the position of the staraccurately. If a planet is orbiting the star, it will induce a small wobble
in the position of the star. This can be observed and again, if it is aregular wobble, then one deduces that it is due to a planet in orbit
around the star. These methods were first applied about twenty yearsago and by now a few thousand planets have been discovered orbiting
distant stars. It is estimated that one star in five has an Earth-likeplanet orbiting it at a distance from the star to be compatible with life
as we know it. Our own solar system was formed about four and a halfbillion years ago, or a little more than nine billion years after the Big
Bang, from gas contaminated with the remains of earlier stars. TheEarth was formed largely out of the heavier elements, including carbon
and oxygen. Somehow, some of these atoms came to be arranged in theform of molecules of DNA. This has the famous double-helix form,
discovered in the 1950s by Francis Crick and James Watson in a hut onthe New Museum site in Cambridge. Linking the two chains in the
helix are pairs of nitrogenous bases. There are four types ofnitrogenous bases—adenine, cytosine, guanine and thymine. An
adenine on one chain is always matched with a thymine on the otherchain, and a guanine with a cytosine. Thus the sequence of nitrogenous
bases on one chain defines a unique, complementary sequence on theother chain. The two chains can then separate and each acts as a
template to build further chains. Thus DNA molecules can reproducethe genetic information coded in their sequences of nitrogenous bases.
Sections of the sequence can also be used to make proteins and otherchemicals, which can carry out the instructions, coded in the sequence,
and assemble the raw material for DNA to reproduce itself.As he said earlier, we do not know how DNA molecules first appeared.
As the chances against a DNA molecule arising by random fluctuationsare very small, some people have suggested that life came to Earth
from elsewhere—for instance, brought here on rocks breaking off fromMars while the planets were still unstable—and that there are seeds of
life floating round in the galaxy. However, it seems unlikely that DNAcould survive for long in the radiation in space.
If the appearance of life on a given planet was very unlikely, onemight have expected it to take a long time. More precisely, one might
have expected life to appear as late as possible while still allowing timefor the subsequent evolution to intelligent beings, like us, before the
Sun swells up and engulfs the Earth. The time window in which thiscould occur is the lifetime of the Sun—about ten billion years. In that
time, an intelligent form of life could conceivably master space traveland be able to escape to another star. But if no escape is possible, life
on Earth would be doomed.There is fossil evidence that there was some form of life on Earthabout three and a half billion years ago. This may have been only 500million years after the Earth became stable and cool enough for life to
develop. But life could have taken seven billion years to develop in theuniverse and still have left time to evolve to beings like us, who could
ask about the origin of life. If the probability of life developing on agiven planet is very small, why did it happen on Earth in about one-fourteenth of the time available?
The early appearance of life on Earth suggests that there is a goodchance of the spontaneous generation of life in suitable conditions.
Maybe there was some simpler form of organisation which built upDNA. Once DNA appeared, it would have been so successful that itmight have completely replaced the earlier forms. We don’t know whatthese earlier forms would have been, but one possibility is RNA.
RNA is like DNA, but rather simpler, and without the double-helixstructure. Short lengths of RNA could reproduce themselves like DNA,
and might eventually build up to DNA. We cannot make these nucleicacids in the laboratory from non-living material. But given 500 million
years, and oceans covering most of the Earth, there might be areasonable probability of RNA being made by chance.As DNA reproduced itself, there would have been random errors,
many of which would have been harmful and would have died out.
Some would have been neutral—they would not have affected thefunction of the gene. And a few errors would have been favourable tothe survival of the species—these would have been chosen by
Darwinian natural selection.The process of biological evolution was very slow at first. It took
about two and a half billion years before the earliest cells evolved intomulti-cellular organisms. But it took less than another billion years forsome of these to evolve into fish, and for some of the fish, in turn, toevolve into mammals. Then evolution seems to have speeded up even
more. It took only about a hundred million years to develop from theearly mammals to us. The reason is that the early mammals already contained their versions of the essential organs we have. All that wasrequired to evolve from early mammals to humans was a bit of fine-tuning.
But with the human race evolution reached a critical stage,comparable in importance with the development of DNA. This was thedevelopment of language, and particularly written language. It meantthat information could be passed on from generation to generation,other than genetically through DNA. There has been some detectable
change in human DNA, brought about by biological evolution, in the10,000 years of recorded history, but the amount of knowledge handedon from generation to generation has grown enormously. He havewritten books to tell you something of what he have learned about the
universe in his long career as a scientist, and in doing so he istransferring knowledge from my brain to the page so you can read it.
The DNA in a human egg or sperm contains about three billion basepairs of nitrogenous bases. However, much of the information coded in
this sequence seems to be redundant or is inactive. So the total amountof useful information in our genes is probably something like a
hundred million bits. One bit of information is the answer to a yes/noquestion. By contrast, a paperback novel might contain two million
bits of information. Therefore, a human is equivalent to about fiftyHarry Potter books, and a major national library can contain about
five million books—or about ten trillion bits. The amount ofinformation handed down in books or via the internet is 100,000 times
as much as there is in DNA.
Even more important is the fact that the information in books can bechanged, and updated, much more rapidly. It has taken us severalmillion years to evolve from less advanced, earlier apes. During thattime, the useful information in our DNA has probably changed by onlya few million bits, so the rate of biological evolution in humans is about
a bit a year. By contrast, there are about 50,000 new books publishedin the English language each year, containing of the order of a hundred
billion bits of information. Of course, the great majority of thisinformation is garbage and no use to any form of life. But, even so, therate at which useful information can be added is millions, if not
billions, higher than with DNA.This means that we have entered a new phase of evolution. At first,
evolution proceeded by natural selection—from random mutations.
This Darwinian phase lasted about three and a half billion years andproduced us, beings who developed language to exchange information.
But in the last 10,000 years or so we have been in what might be calledan external transmission phase. In this, the internal record ofinformation, handed down to succeeding generations in DNA, haschanged somewhat. But the external record—in books and other long-lasting forms of storage—has grown enormously.
Some people would use the term “evolution” only for the internallytransmitted genetic material and would object to it being applied toinformation handed down externally. But he think that is too narrow aview. We are more than just our genes. We may be no stronger orinherently more intelligent than our caveman ancestors. But what
distinguishes us from them is the knowledge that we have accumulatedover the last 10,000 years, and particularly over the last 300. He think it
is legitimate to take a broader view and include externally transmittedinformation, as well as DNA, in the evolution of the human race.
The timescale for evolution in the external transmission period is thetimescale for accumulation of information. This used to be hundreds,or even thousands, of years. But now this timescale has shrunk toabout fifty years or less. On the other hand, the brains with which we
process this information have evolved only on the Darwiniantimescale, of hundreds of thousands of years. This is beginning tocause problems. In the eighteenth century, there was said to be a man
who had read every book written. But nowadays, if you read one book aday, it would take you many tens of thousands of years to read through
the books in a national library. By which time, many more books wouldhave been written.This has meant that no one person can be the master of more than asmall corner of human knowledge. People have to specialise, innarrower and narrower fields. This is likely to be a major limitation inthe future. We certainly cannot continue, for long, with the exponential
rate of growth of knowledge that we have had in the last 300 years. Aneven greater limitation and danger for future generations is that we
still have the instincts, and in particular the aggressive impulses, thatwe had in caveman days. Aggression, in the form of subjugating or
killing other men and taking their women and food, has had definitesurvival advantage up to the present time. But now it could destroy the
entire human race and much of the rest of life on Earth. A nuclear waris still the most immediate danger, but there are others, such as the release of a genetically engineered virus. Or the greenhouse effectbecoming unstable.
There is no time to wait for Darwinian evolution to make us moreintelligent and better natured. But we are now entering a new phase of
what might be called self-designed evolution, in which we will be ableto change and improve our DNA. We have now mapped DNA, which
means we have read “the book of life,” so we can start writing incorrections. At first, these changes will be confined to the repair ofgenetic defects—like cystic fibrosis and muscular dystrophy, which arecontrolled by single genes and so are fairly easy to identify and correct.
Other qualities, such as intelligence, are probably controlled by a largenumber of genes, and it will be much more difficult to find them and
work out the relations between them. Nevertheless, I am sure thatduring this century people will discover how to modify both
intelligence and instincts like aggression.
Laws will probably be passed against genetic engineering withhumans. But some people won’t be able to resist the temptation to
improve human characteristics, such as size of memory, resistance todisease and length of life. Once such superhumans appear, there are
going to be major political problems with the unimproved humans,who won’t be able to compete. Presumably, they will die out, or
become unimportant. Instead, there will be a race of self-designingbeings, who are improving themselves at an ever-increasing rate.
If the human race manages to redesign itself, to reduce or eliminatethe risk of self-destruction, it will probably spread out and colonise
other planets and stars. However, long-distance space travel will bedifficult for chemically based life forms—like us—based on DNA. The
natural lifetime for such beings is short compared with the travel time.
According to the theory of relativity, nothing can travel faster thanlight, so a round trip from us to the nearest star would take at leasteight years, and to the centre of the galaxy about 50,000 years. Inscience fiction, they overcome this difficulty by space warps, or travelthrough extra dimensions. But I don’t think these will ever be possible,no matter how intelligent life becomes. In the theory of relativity, ifone can travel faster than light, one can also travel back in time, andthis would lead to problems with people going back and changing thepast. One would also expect to have already seen large numbers of
tourists from the future, curious to look at our quaint, old-fashionedways.
It might be possible to use genetic engineering to make DNA-basedlife survive indefinitely, or at least for 100,000 years. But an easier
way, which is almost within our capabilities already, would be to sendmachines. These could be designed to last long enough for interstellar
travel. When they arrived at a new star, they could land on a suitableplanet and mine material to produce more machines, which could be
sent on to yet more stars. These machines would be a new form of life,based on mechanical and electronic components rather thanmacromolecules. They could eventually replace DNA-based life, just asDNA may have replaced an earlier form of life.
What are the chances that we will encounter some alien form of life aswe explore the galaxy? If the argument about the timescale for the
appearance of life on Earth is correct, there ought to be many otherstars whose planets have life on them. Some of these stellar systems
could have formed five billion years before the Earth—so why is thegalaxy not crawling with self-designing mechanical or biological life
forms? Why hasn’t the Earth been visited and even colonised? By theway, I discount suggestions that UFOs contain beings from outer
space, as I think that any visits by aliens would be much more obvious—and probably also much more unpleasant.
So why haven’t we been visited? Maybe the probability of lifespontaneously appearing is so low that Earth is the only planet in the
galaxy—or in the observable universe—on which it happened. Anotherpossibility is that there was a reasonable probability of forming self-
reproducing systems, like cells, but that most of these forms of life didnot evolve intelligence. We are used to thinking of intelligent life as an
inevitable consequence of evolution, but what if it isn’t? The AnthropicPrinciple should warn us to be wary of such arguments. It is more
likely that evolution is a random process, with intelligence as only oneof a large number of possible outcomes.
It is not even clear that intelligence has any long-term survival value.
Bacteria, and other single-cell organisms, may live on if all other life onEarth is wiped out by our actions. Perhaps intelligence was an unlikely
development for life on Earth, from the chronology of evolution, as ittook a very long time—two and a half billion years—to go from single
cells to multi-cellular beings, which are a necessary precursor to intelligence. This is a good fraction of the total time available before
the Sun blows up, so it would be consistent with the hypothesis thatthe probability for life to develop intelligence is low. In this case, we
might expect to find many other life forms in the galaxy, but we areunlikely to find intelligent life.
Another way in which life could fail to develop to an intelligent stagewould be if an asteroid or comet were to collide with the planet. In
1994, we observed the collision of a comet, Shoemaker–Levy, withJupiter. It produced a series of enormous fireballs. It is thought the
collision of a rather smaller body with the Earth, about sixty-sixmillion years ago, was responsible for the extinction of the dinosaurs.
A few small early mammals survived, but anything as large as a humanwould have almost certainly been wiped out. It is difficult to say how
often such collisions occur, but a reasonable guess might be everytwenty million years, on average. If this figure is correct, it would mean
that intelligent life on Earth has developed only because of the luckychance that there have been no major collisions in the last sixty-sixmillion years. Other planets in the galaxy, on which life has developed,may not have had a long enough collision-free period to evolveintelligent beings.
A third possibility is that there is a reasonable probability for life toform and to evolve to intelligent beings, but the system becomes
unstable and the intelligent life destroys itself. This would be a verypessimistic conclusion and he very much hope it isn’t true.
He prefer a fourth possibility: that there are other forms of intelligentlife out there, but that we have been overlooked. In 2015 he was involved
in the launch of the Breakthrough Listen Initiatives. BreakthroughListen uses radio observations to search for intelligent extraterrestriallife, and has state-of-the-art facilities, generous funding and thousands
of hours of dedicated radio telescope time. It is the largest everscientific research programme aimed at finding evidence ofcivilisations beyond Earth. Breakthrough Message is an international
competition to create messages that could be read by an advancedcivilisation. But we need to be wary of answering back until we have
developed a bit further. Meeting a more advanced civilisation, at ourpresent stage, might be a bit like the original inhabitants of America
meeting Columbus—and he don’t think they thought they were better off
for it.
Thank you very much for reading my blog..........
😊😊😊😊😊 🙂🙂🙂🙂🙂🙂