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PS700 Colloquia
Daniel Hayden 3rd Year Physics
Are we Alone in the Universe?
Given by,
Professor Michael D. Smith
At Kent University
Colloquium asking are we alone in the Universe? Given on the 7th of November 2006, by
Professor Michael D. Smith from the University of Kent, at 8pm in ELT2.
Professor Michael D. Smith’s colloquium addressed the following topics:
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Do we share our origins?
What are the essential properties of life?
The Evolution and Hierarchical structure of life
The Evolution of the Universe
Conditions for Life
The Drake Equation
Are we alone in the Universe?
This was a talk done by Michael D. Smith for the Space society at the University of Kent,
Professor Smith started by saying that unlike most talkers he intended to actually answer
(in his opinion) the question of whether we are alone in the Universe. He explained that
some of the most frequently asked questions posed to an Astronomer are;
1.
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5.
I am a Virgo, what’s my future?
Do you really get paid?
Why don’t you look like one?
Do you believe in UFO’s?
Are we alone?
Despite the first four being some what ambiguous, the last would try to be made clearer
from this talk. As an aside Professor Smith showed us a link to a website that he had
made for everyone to view strange things seen in the sky at night, Web Address:
http://astro.kent.ac.uk/mds/lgm.htm .
Professor Smith explained that the essential properties of life revolved around three main
areas; Reproduction, the ability to reproduce and thus further your kinds’ existence,
Metabolism, the ability for living organisms to process required chemical compounds
into nutrients and lastly Mutations which create variations in any given gene pool, the
undesirable of which being filtered out by the process of natural selection (Survival of the
fittest). He then moved on to talk about intelligent life and asked “How might we define
intelligent life? Insight? Recognition abilities? Abstraction?” The answer is the
Thurstone list. The Thurstone list was made by one Louis Leon Thurstone and contains
all of the attributes for intelligent life. No one person is adept at all of the abilities Smith
explained but intelligent life exhibits at least some combination of those listed, the
Thurstone list follows:
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Spatial Visualisation
Number Facility
Verbal comprehension, word fluency
Associative Memory
Logical thinking
Perceptual speed
The talk then moved on to the Hierarchical structure of life, starting with chemical
elements binding into molecules and proceeding with those building block molecules into
amino acids, nucleotides which further led to macro molecules such as DNA and
proteins. From there “organelles” (Cell homeostasis, internal cell function) form which
make up cells which exhibit growth, specialisation and death. These cells make up the
tissue we know like blood, muscles, bone etc. which in turn are apart of limbs and
physiological systems (organism homeostasis). This ultimately leads to individual
organisms and animals (physiological functioning), populations and competition for food
i.e. the food chain. From this communities grow that all the species in an ecosystem are
apart of and with ecosystems come species interdependency. Finally Biomes can be
described, which are major regional areas of distinctive plant and animal life best adapted
to the regions natural environment. This finally culminates in the planet, Earth in our
case and a biosphere with global resource cycles. The most important out of all of this is
at the very bottom of the structure; Chemicals, and at the very top end; The planet, with
these two everything else in between should be possible.
Professor Smith then went on to say he was going to explain the evolution of life by
starting from the big bang and working up to actual life, below is a diagram used in the
presentation to explain the origin of the Universe which Smith went through;
He explained that the Big Bang was thought to have happened 13.7 billion years ago and
that the formation of the solar system and Earth only happened 4.6 billion years ago. Up
until around 3.8 billion years ago there had been a phase of intensive impacts forming
such things as water and other complex molecules. About 3.6 billion years ago there was
finally the appearance of life all be it Prokaryotes (Archaen and Bacteria) until recently (2
billion years ago) as Eukaryotes which are generally much larger organisms and made up
of complex cell structures. About 600 million years ago cell assembly started to take
place and this eventually led 2.5 million years ago to the appearance of Human beings
who started to form civilisations around 2000 years ago. Beyond this no one can know
but Professor Smith posed a question of “Is there somewhere beyond Darwinism, self
replicating designers?”. We observe the red shift of the expansion of the universe at
present as about 0.4, extrapolating this back to 13.7 billion years ago gives us a red shift
estimate of ~1000. From the way life has evolved to this date, Smith explained, life
seemed to evolve at an accelerating rate and said that with encoding, metabolism and
reproduction, you have life (actual biological life). He also said that there are different
types of “life” some listed below;
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Spiritual (Believe it or not)
Mechanical (Robots)
Virtual Life (The algorithm strikes back)
Biological
But that in this talk we will only be concerned with biological life. Next came the
conditions for biological life to develop, life as we know it requires an abundance of
carbon (rich chemistry), water (delicate solvent) and living space (Planets). Carbon is
stable and is our form of life, without it we would not exist, but silicon as a base for life
(as in some SciFi programmes) is possible. Water however seems to be vital wherever
we go, it is not impossible that it isn’t essential for all types of life in the Universe but as
far as we know it probably is.
The next main topic of the talk was the Evolution of the Universe explained in seven
simplified stages.
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Quantum Gravity Age
This was the Planck Era and was for the first 10^(-43) seconds of the Universe where the
temperature was around 10^32 Kelvin. The universe was so small that Gravity and
quantum mechanics were comparable and it is thought that our present four forces
(Strong Nuclear, Weak Nuclear, Electro-magnetic and Gravity) were combined into one
super force.
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Particle Physics Age
Inflation started 10^(-36) seconds after the big bang when the temperature was thought to
be around 10^28 Kelvin. At this temperature it is thought that Quarks, electron, photons,
neutrino and their anti-particles could exist. At 10^&(-10) seconds, the electroweak
transition caused a slight matter excess which is why we see matter and not anti matter
around us today (All though if anti matter were the dominant then that is what we would
call matter today anyway to it is relatively arbitrary which was more abundant). Then at
around 10^(-6) seconds (a 10 millionth of a second) after the big bang quarks were able
to form protons and neutrons (Up, Down, Up and Down, Up, Down, respectively).
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Nuclear Age
One second after the big bang when the temperature has fallen to around 10^10 Kelvin,
Protons, some Neutrons and neutrinos can exist. 10 seconds in electrons and positrons
annihilate, and ~300 seconds in when the temperature was approximately 10^8 Kelvin
Helium and Deuterium formed from the protons and remaining neutrons.
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Light Age
Radiation dominates this age (Mass/Energy). At 10,000 years old the universes’
temperature has fallen to ~30,000K and tiny fluctuations have started to appear. At
300,000 years with the temperature at 3,000k, atomic hydrogen can finally form from
protons and electrons, the Universe becomes transparent and Radiation can de-couple
with matter.
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Chemistry Age
Also known as the dark ages, Universe continues to expand. 100 million years after the
big bang, temperature being around just 100K, molecular hydrogen forms and cools the
gas and the matter fluctuations start to grow. 180 million years in red shift is around 20,
first stars form (100-1000 times more massive than the sun) leading to the middle ages of
feedback and contamination from stars.
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Gravity Age
The renaissance if you will, dark matter collapses into halos. 500 million years from the
beginning larger and larger galaxies have finally formed, massive black holes grow
forming quasars. 3,000 million years in galaxy discs form and 5,000 million years in rich
clusters of thousands of galaxies are in existence.
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Biology Age
This age is basically up to the present. Stellar evolution created left over metals and dust
resulting in planet formation and ultimately us. It is in this age that the universe also
started to apparently accelerate.
Professor Smith explained early proto-star formation, all the way from the initial cloud
nebulae to a class three proto-star a diagram of which can be found on the next page
(Diagram is actually from the presentation itself).
He then explained planet formation and that it required Dust and heavy elements i.e.
metals (N.B. in Astronomy, metals refer to anything other than hydrogen and helium).
But in the beginning there were only non-metal elements around, the first stars were
made entirely of hydrogen and helium meaning;
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No planets
No life
Nuclear fusion in core
Formation of C, N, O up to Fe
The heavier elements only came into other systems later, through injection via
supernova-explosions causing enrichment of interstellar material with heavy elements.
When this was done Professor Smith explained that planet formation could take place
with rocks clashing from dust particle sizes up to kilometre radius size objects able to coaless and eventually form planets
Professor Smith said that there are actually Very specific conditions for life and talked
about the possibility of life on one of Jupiters moon’s, Europa which was never thought
possible until recently when there was the realisation of the versatility of life. The
problem for life comes when you look at the habitable zones in any given galaxy, from
the diagram used in the presentation below you can see that only a small band can sustain
life. Outside the band there are too few heavy elements and so no planets can form,
inside the band there are too many super nova explosions and close encounters with other
stars meaning no life can get off the ground before it is destroyed.
But even within this “Habitable Zone” there are an abundance of problems. There is a
great importance on the individual solar system for life to be able to thrive. The solar
system must be stable and this is rare as stars aren’t usually found singularly but
generally in pairs or more, these systems are inherently unstable. We are also very lucky
that we have a large “planetary protector” of sorts in Jupiter which gives Earth a much
greater chance of avoiding meteor collision through hitting Jupiter itself and thus
enabling a longer period of stability for life to evolve. Professor Smith then gave a very
recent example of the Shoe Maker comet hitting Jupiter. There are also many other
factors such as correct planetary size to hold on to an atmosphere, stable planetary orbit
and favourable plate tectonics that all facilitate the growth of basic and intelligent life.
On the next page is a basic summary of all the points I have just gone over that Professor
Smith used to explain the 10 main factors for “Rare Earth” like planets.
This leads us onto the Drake Equation created by Frank Drake (Shown Below) in 1961
which consists of seven factors for the possibility of life.
All of the variables above are fractions apart from the first which has units of per second
and the last which has units of seconds (Thus cancel giving a dimensionless answer).
Professor Smith then went on to try and estimate each of the factors in the equation to
give a ball park figure for the abundance of life. On the next page I have made a
summary of all of his estimations;
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R: From observed ~1 but only about one per year is an “appropriate” star.
Fp: From extras-solar detection methods ~ 170 systems found.
Ne: None as yet because sensitivity of methods to date are not sufficient but
simulations show that 7%-60% of known planetary systems could have Earth like
planets in the habitable zone.
Fl: Evolved quickly on Earth, still remote possibility of other life in our solar
system, water is known to be fairly common in dust clouds. New Darwin mission
is expected to help. Results in 2020 are expected to show ~10% of Earth like
planets will have life. But as far as we know = 1.
Fi: Complex life needs lots of time to evolve, which is a general problem except
in rare cases like us. Complex life only came about in the last 600 million years,
intelligent life in the last 3 million years, thus this variable will be very low
indeed.
Fc: Needs time just like intelligent life, but for that life to evolve enough to learn
how to communicate extra-terrestrially is probably quite long (Although
comparatively there would not be much time between Fi and Fc on the scale of
things).
L: The average lifetime of a civilisation doesn’t look good for us. There are
limited resources, population fluctuations due to birth, death and disease. Not to
mention climate changes, wars that could potentially wipe out races with nuclear
warfare or the threat of extinction through meteor impacts like the dinosaurs are
thought to have experienced. The expected lifetime for an intelligent civilisation
could be almost anything, 100 years? 1000 years? It all depends, only simple life
is more stable with L= ~ 6 billion years.
The outcome of all of this depends on whether you are optimistic or pessimistic on the
length of life for a civilisation Professor Smith explained, below are two tables the first
showing optimistic predictions, the second pessimistic;
Optimistic: One intelligent civilisation per Galaxy but abundance of simple life.
Pessimistic: Only one intelligent civilisation for every 1000 galaxies.
CONCLUSION:
LIFE IS COMMON IN THE UNIVERSE BUT COMPLEX OR INTELLIGENT
LIFE IS RARE.
As a note Professor Smith also mentioned that if you replaced the average star formation
rate in a galaxy to that of the entire universe, the star formation rate goes up to 100
million stars per second and this gives a tidy some of 10 million civilisations in our
universe which in turn gives a number or 10x10^(15) intelligent beings in our universe if
on average each civilisations is equal in size to our own.
Questions:
Q. What ever happened to the signal received thought to be from outer space but
never heard of again?
A. M.D.Smith says he doubts it was true if you haven’t heard any more.
Q. Is there a lot of controversy over L? (referring to lifetime of a civilisation
variable)
A. Thinks we should set off from Earth in years to come, our planet will soon
become old fashioned and we are running low on resources. In too years there is
no reason why we can’t have moved off the planet considering progress in the last
50 years and thus last more than millions of years per civilisation.
Q. Is it a valid question to ask if people would deplete resources before they could
leave?
A. It is a valid question, you have to be lucky enough to be on a high material planet
and if you aren’t then possible fighting over the low resources could result in the
end of the civilisation in question.
Q. Is there life on Europa in your opinion?
A. Not as sceptical as he used to be and it is possible that there could be life under
the surface if it is warm enough
Q.
A.
The second law of thermodynamics has doomed us all because of increasing
expansion of the Universe.
No, Entropy increasing but we are becoming more orderly. Thermodynamics is
limited to individual systems, if this weren’t the case galaxies would not have
formed.
Q. Is it a coincidence that Humans came from Monkeys?
A. Don’t really understand the question, but possible it is a coincidence.
Q. (Re-defining question above) On another planet like ours what will life look like?
A. It is possible that it may be a lot like us, because our height etc is well suited to
our existence.
Q. In our search for civilisations should we look inwards towards the centre of the
Galaxy because of higher metallicity or are we looking randomly?
A. We are looking randomly at present but civilisations may prefer to move closer to
the centre for more resources and so would be a good place to look.
Q. Will the “Darwin” project help look for life? Could fluctuations in the O Zone
like ours be a sign?
A. Very difficult to model, so no.
Strengths:
M.D.Smith is obviously very passionate about the subject of Life in the Universe as I
believe he brought it alive for everyone present to enjoy. Clear spoken throughout and
having a well paced structure helped the sometimes seemingly complex ideas (For nonscientists) appear simpler. I was impressed with the relevance of a lot of the images used,
helping the ideas laid out in words be reinforced by visual means, this was especially true
with the diagram of the galaxy in aid of explaining the different zones, being habitable,
too far away i.e. low in material or too close where there is high metallicity but too much
turbulence for per longed life. Professor Smith also brought a more personal feel to the
presentation, it did not feel as if he was merely reading a rehearsed speech but more that
he was taking us through the logical progression of how to determine the chances of life
in our universe and even more so, what life was. I was happy about this because it didn’t
feel like you were being lectured but more as if you were “along for the ride” and it
undoubtedly made it more enjoyable for everyone. Every term or idea brought up in the
presentation was described so that lay and scientist alike could understand, especially
during the part about the Drake equation where it would be quite easy to get lost in the
numerous factors involved, Smith handle each factor equally and fully. The power point
presentation was colourful and clear fonts were used, there were great animations and
there was not more information than there needed to be on the slides even though at times
a lot of text was required. Overall I found the presentation enjoyable and learnt a lot that
enabled me to go away and think about the topic more.
Weaknesses:
Obviously mainly set at a non-scientific audience (Even though it was still fully
enjoyable and mixed with “spice” for the scientists). Even though minimal text passages
were used it still felt at times like there was a lot on the slides to read, this led to
sometimes trying to read a lot and inevitably therefore listening less. This was
disappointing because when you stopped yourself reading the slide and just listened to
Professor Smith, all of the points were still fully and clearly covered so it felt that less
information could have been provided on the visual presentation while still retaining the
same effect when combined with the oral presentation. At the end the presentation did
pick up a bit of pace which felt a little fast, but to be fair the overwhelming feeling was
that 50 minutes was not long enough to cover everything you could say about the topic
and so Professor Smith did well with the time he had, it’s just a pity that with an
unconventional extra 10 minutes the presentation could have ended in the same relaxed
sense in which it started. In the questions at the end, Professor Smith was sometimes a
bit vague in the answers he gave, this was most likely due to the obscurity of some of the
questions he was posed and so not much blame could be laid with him but it made it
sometimes unclear if he had answered the question or not.