How Big is space? Part 1

As Douglas Adams writes in Hitchhiker's Guide to the Galaxy, "Space is really, really big. You just won't believe how vastly, hugely, mind-bogglingly 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"

So, let's attempt to visualize just how big it is.

First, we look at Earth.  One little planet.

A few years back, I took a drive from my hometown of Calgary, Alberta, down to Orlando, Florida, a trip of roughly 5,500 kilometres (3,400 miles).  It took five days.  Five full days of driving.  The trip back took a week, as it included a side trip to Santa Fe.  Before I got my driver's license, though, I would hitchhike.  Which meant that sometimes, I had to walk long distances.  A walk of 20 kilometres only takes 10 minutes in a car, but it took me four hours.  So, I have a pretty good idea just how far it is across America.

Now, 5,500 kilometres is pretty far, but if there were a road stretching around the Equator of Earth, it would be a little more than seven times further.  It would take roughly six weeks of long, full day drives. On foot, it would take you about two years, at twelve hours a day.

At this point, I'll start employing analogies, so you can picture this.

Imagine a perfect, 1:1 million scale globe of the Earth.  At least one such globe exists.  On this scale, the Earth is 12.756 metres (41 feet 10 inches) in diameter.  In my trip across North America, I'd cover about a metre (3.28 feet) a day on that globe.  My 4 hour walk covered about 2 mm (1/12th of an inch).  Just as a side note, the edge of space is defined as 100 kilometres, so on that globe, it would be about 10 cm (4 inches) off the surface.  Of course, it's only breathable to about 5 km (5mm) on that scale.

A trip to the moon and back is the longest "straight line" trip humans have undertaken.  It's 383,000 kilometres to the moon, so a return trip is 766,000 kilometres.  19 trips around the Earth's equator.  On our "big globe" model, the moon is 383 metres (just under 1/4 mile) away.

The next big leap is to the Sun.  Fortunately, that distance will serve as a convenient yardstick for the great distances to come.

The Earth orbits the Sun at a distance averaging 150 million km, about 390 times the Earth-moon distance.  For our big globe model, the 1:1 million scale, this is equivalent to 150 kilometres, or about an hour and a half's drive at highway speed.  If you could equate your highway driving to the model scale, your speed would be roughly a little less than 1/10th the speed of light.  By definition, the Earth-sun distance, actually about 149 600 000 kilometres (92 900 000 miles) is 1 Astronomical Unit, or A.U.

Another thing to consider is that on this scale, the Space Shuttle, in low orbit, moved at about 7.8 millimetres (1/3 of an inch) per second.  Our fastest interplanetary spacecraft, Voyager 1, is currently moving 3.6 A.U. per year.  At 1:1 million scale, that's 61.43 metres per hour, so it covers the real Earth-moon distance every 6 hours and 15 minutes, and 1 A.U. every 101.5 days.

At this point, we have to reduce scale, so that 1 A.U. (Earth-sun distance) is just 25.4 mm, or 1 inch.  I've chosen this particular scale for one simple reason.  It turns out, the ratio of a Light-year to 1 A.U. is almost exactly the same as the ratio of 1 mile: 1 inch.

On this scale, the Sun would be a barely noticeable speck the size of a grain of fine sand.  The Earth would be only visible through a microscope on that scale.  Earth orbits 1 inch away from the sun.  Mars orbits about 1 1/2 inches (3.8 cm) away from the center, and Jupiter is about 5 inches (12.5 cm) out.  Saturn lazily carves its circle, 10 inches (25.4 cm) from the Sun every 29.4 years.  Uranus is about 18 inches (46 cm) out, and the outermost planet, Neptune, is 30 inches (76 cm) from the Sun.  Our furthest probe, traveling since 1976, Voyager 1, is now roughly 130 A.U. from the Sun, or just under 11 feet on this scale.  Light takes 18 hours to traverse this distance.

A light year is defined as the distance light travels in a year, or 9,460,730,472,581 kilometres (5,878.625,373.184 miles), or, on this scale, 5,270 feet, ten feet short of a mile.

How many Extraterrestrial Intelligences in the Milky Way Galaxy?

These are my estimations, predictions, based on what I wrote the previous 2 entries:

Number of Stars in Milky Way Galaxy:  200 billion

Number of Planets in Milky Way Galaxy:  1 trillion

Number of Earth / Super Earth Planets in Habitable Zone:  100 billion

Number of Planets with Life:  250 million

Number of Planets with Multi-cellular Life:  30 million

Number of Planets with Sentient species:  100,000

Number of Planets with Civilizations:  5,000

Number of Planets with Space-Faring, Radio communicating Civilizations:  less than 100


That's not a lot.

Given the sheer size of our galaxy, on average, the nearest such civilization is at least 10,000 light years away.

A light year is 9.46 trillion kilometres (5.88 trillion miles).  Our nearest "friends" are something on the order of 95,000,000,000,000,000 kilometres  (59,000,000,000,000,000 miles)

Our fastest interstellar probe (Voyager 1), travels 540 million kilometres (336 million miles) per year.

If it just happens to be traveling in the right direction, it'll take 175,000,000 years to reach it.  They'll probably be long gone by then.

How Likely is Extraterrestrial Intelligence? Part 2

In the previous entry, I outlined a brief sketch of the Drake Equation.  For more on that, check Wikipedia's article - it's a little more in depth:

http://en.wikipedia.org/wiki/Drake_equation

I had described the conditions likely leading to intelligent life.  But, this is a bit tricky.  Cetaceans and Octopi are intelligent, perhaps even sentient, but because they live underwater, cannot develop any form of permanent records or technology.

The other problem is that human level intelligence is very expensive.  Our brain demands some 20% of the body's energy resources, and a very long childhood to develop that brain.  This price means humans are nowhere near the fastest species for our weight class, nor the strongest.  Our teeth and nails are terrible weapons compared with a Cougar's, and they run three times as fast as we do.  Our brain must be employed to make up for that.

And it does, extremely well.  We throw things well.  We are the Jackie Chan of species, utilizing anything in our environment for both attack and defense.  This creativity is what led to civilization in the first place.  Hunting in groups meant we had to learn to communicate more than just raw emotions.  "You circle around back" was probably one of the first things we figured out how to communicate.  Of course, it wouldn't have been in English, which has only been around for the past couple of millennia.  The first proto-languages probably appeared 50,000 years ago or more, and those with extremely limited vocabularies.

At any rate, it took civilization to finally harness the true potential of high intelligence.  Suddenly, language had much more to describe.  Humans created and innovated new tools, new ideas, a feedback loop which has been tightening ever since.

Ultimately, this gave rise to the Industrial Revolution, and with it, machinery, and non-verbal communication at a distance: first telegraph, then radio.

So, it's pretty much a given, that any extraterrestrial intelligence would need to follow a similar path.  But, though it might seem inevitable, we've had some fortune along the way to make it all possible.

No large meteoric impacts on our planet the past few million years.
No supernovae within 30-40 light years of our planet.
No sudden, catastrophic climate change.
No particularly voracious, nearly impossible to fight off predators.
No large scale outbreak of some lethal disease.  (The Black Death of the 14th Century killed a lot, but it didn't kill everybody.)

Even so, Genetic Researchers have determined that sometime around 70,000 years ago, we came very close to extinction.  Every human alive today is descendant from that one tribe that survived.

Neil deGrasse Tyson is fond of saying that the Universe is trying to kill us.  Not quite, but it certainly does make survival very difficult.

So, an extraterrestrial intelligence has to survive against the same long odds.

Only to have to deal with their own violent nature.

Although writers love to suggest that Aliens would look on humanity with disdain at our violent nature, our propensity for destruction, chances are, they would've had to survive against the same issues.  Why?

As I outlined before, predator species tend to be the more intelligent, as they have to outthink their prey.  Also, meat eaters get much more energy from their food, and thus have more spare time.  Predatory species are naturally more violent.  Survival means beating the competition, and that means having a more aggressive nature.  Can you even imagine a Champion Boxer telling the media, "Oh, I don't like to fight.  We should just talk our differences over."  We had to beat our way to the top through a lot of competition.

However, this leads to an interesting conundrum.

What happens when a violent, competitive species begins developing high technology?  Any competition between groups (pretty much inevitable) leads to development of more powerful weapons, and eventually, weapons powerful enough to completely annihilate themselves.  The Universe is quite possibly littered with the remnants of intelligent civilizations that bombed themselves into oblivion, or merely back into the Stone Age.

And it isn't even deliberate weapons that we could destroy ourselves with.  The necessary step of an Industrial Era has led to dangerously high Carbon Dioxide levels in our atmosphere.  We don't even know what the true ramifications of that are, and we're still putting the stuff out at record levels every year.  Even without bombs, we might find our civilization wiped out by ever more violent storms, ever more violent oceans, and a runaway greenhouse effect that eventually kills off all life and boils away our oceans.

The desire to compete has hampered nations' willingness to drastically, quickly change over their energy production to more sustainable technologies.

We have spaceflight, but barely.  As yet, we cannot move large numbers of people safely off planet to keep our species alive.  And we won't, for quite some time.  We're treading a fine line, here.

Now, perhaps Extraterrestrial Intelligences have been a little smarter, a little more willing to work together to protect their home planet while they're still dependent on it.  If they were, and they eventually begin colonizing other systems, they're safe.

Except if their home galaxy's central black hole decides to swallow a few dozen stars in a single year, and blasts out enough gamma radiation to exterminate half the galaxy all at once.

Maybe Neil deGrasse Tyson is right after all.

How Likely is Extraterrestrial Intelligence? Part 1

Two answers on that one.

First, given the vastness of the Universe and the sheer mind boggling number of stars and potential planets, it is pretty much inevitable.

However,

Given the incredible odds of many of the "processes" required, they may be few and far between.  Most people have heard of the Drake Equation, which attempts to predict the number of intelligent, communicative civilizations out there.

In short, it looks like this:

 


N = Total civilizations.  Each term is multiplied together to get a net product.  Many of these values are unknown and must be guessed at, which leads to a pretty large variance of the N value.

R = Total number of stars in the galaxy
Fp = The fraction of those stars which have planets
Ne = Number of Planets each star has, on average
Fl = Fraction of Planets which develop Life
Fi = Fraction of those planets which Life becomes Intelligent (self aware)
Fc = Fraction of those planets with Intelligent Life which learn to broadcast into space
L  = Length of Time such civilizations broadcast into space

The first Term, R, is reasonably well known - around 200 billion

Only recently (last 2-3 years) has Fp and Ne been narrowed down a bit.  Although Drake estimated it to be about one for each term, I believe we can be more generous here.  I believe, ultimately, planets are pretty commonplace, at about five or so per star.  Our star has 8, and I'm sure there's stars out there with many more.  Many near the Galaxy's core, may not have planets, as frequent close encounters with other stars may have dislodged those planets from their orbits and sent them careening through interstellar space.  It's pretty much a given that any planet wandering interstellar space is too cold for life.

As alluded to before, planets aren't likely to produce Life if they're too hot, like Mercury.  And, they're not likely to develop Life, if they're too cold, like Jupiter's moons Ganymede or Callisto.  Forget Jupiter.  Gas Giant planets are very inhospitable.  No solid surface, high concentrations of poisons like Hydrogen, or inert like Helium, extremely violent winds, lethal levels of radiation.  Hydrogen does not form complex bonds, and in large quantities, tends to rip apart complex bonds that are necessary for life.

Life needs stability, too.  A wild, swinging orbit that goes from Mercury's distance to Jupiter's does not lend itself to life, either.  To form and keep life, a planet should be large enough to hold onto a protective atmosphere.  The moon is in the same orbit as Earth but with no atmosphere: it is perpetually hammered by raw solar radiation.  Mars is almost big enough, but in the distant past, it cooled enough for its core to stop circulating around, so it no longer has a global magnetic field.  Without that field, Mars's atmosphere was stripped away by the Sun's particle flux, and it, too, gets hammered hard by radiation.  If Mars has any life, it's buried and forever banished to single cell status.

In summary, Life is probably pretty uncommon - probably only developing in one of every 100 to 1,000 systems.

Now, here's the kicker.  Going from single celled to multicellular was likely a huge jump.  It's reasonable to assume that single celled life cannot attain intelligence.  Far too simple.  To develop the complexity that breeds intelligence, cells need to band together in huge numbers.  Earth was populated by single celled life for much of its history - close to 3 billion years.  It was only about 600 million years ago, that nature figured out, Aha! Together we are strong.

But, multicelluar life is clearly not enough.  Earth grew multicellular life for 600 million years before humanity showed up on the scene.  Nature does not deliberately spawn intelligence.  Instead, every species tends to respond to local pressures, adapt to local conditions.  The Predator-Prey battle was a pretty critical factor, causing numerous varying arms races for speed, size, strength, and intelligence.  Only the fastest Prey escaped.  Only the fastest Predators caught Prey.  Competitive species battled it out for survival, both "improving" as a consequence.  On Earth, Predators are generally smarter than Prey.  This is because it's harder to plan an attack than it is to escape.

So, out of 600 million years of multicellular life, high intelligence has only been around about 2 million years.  One could argue that Cetaceans (Whales etc.) have high intelligence.  True, I believe they do.  But, technology requires the species be on land.

Why?  Because it's pretty difficult to build anything permanent under water.  Humans have hands.  This is really important.  Fins just aren't good for any kind of craftsmanship.  Nor writing.  And forget metalworking.  That requires fire.

Aliens (the Fermi Paradox)

First off, let me say that I do believe in Extraterrestrial Life.  However,

I do not believe such life has visited Earth.  Ever?  Not sure about that, but certainly not in the past century.  Contrary to UFO enthusiast's claims, I just don't believe there's any evidence to support it.

I really do believe that if an extraterrestrial intelligence visited Earth, the evidence would be pretty widespread and undeniable.  Contrary to many conspiracy theorists, the media in the Western world is simply too widespread, too diverse, to enter into collusion with a "hush" conspiracy.  In other words, even if the government of the United States was able to muzzle their own media, they wouldn't be able to quiet the reports from, say, Germany, or France, or Japan.

Governments can't even agree on many mundane things, such as tariffs, much less something huge that affects all people.  At any rate, I digress.

Along with media, most industrialized countries possess some form of very sensitive radio equipment - large multimetre dishes that collect radio energy in the nanowatt range.  It would be very difficult for an alien spacecraft to just sneak up on us.  Their communications with home base would be picked up by our telescopes, as they would be pretty much on a direct line of sight with us.  In their various scanning of the sky, some country would pick up the broadcast and the news would spread like wildfire through the world before we'd even decoded the message.

I don't believe in this nonsense about "subspace" or some form of superluminal waveform that we are unaware of.  The laws of Physics don't point to any form of "missing" energy that we are unable to read.  Granted, we're not very good at picking up neutrinos (the vast majority pass right through the Earth completely unaffected by the teratons of rock), but they aren't superluminal, either.  Other than the fact one wouldn't have to worry about such messages being blocked by intervening dust and gas or planets in space, they don't make a very good communications medium.

The point I was originally trying to get to, is that space is vast.  Incredibly so.  Therefore, travel to another star system is no trivial feat, not even by theoretically highly advanced aliens.  Setting up such a mission would take great planning and great expenditure of resources and intelligence.  They wouldn't waste all that sneaking around in trailer parks or cornfields.

We'd hear about the arrival probably months in advance, from the Kuiper Belt or outer solar system, and the whole world would be pretty well prepared on some level for it.

Our radio waves have been traveling outward for over a century now.  Granted, for the first few decades, the transmissions were so weak that they'd be easily lost in the background noise of the galaxy.  But chances are, if somebody has already picked up our radio waves, they would have to be at least as advanced as us, and therefore, we'd likely have picked up theirs by now.  But, if they haven't, the number of stars our transmissions reach increases to the cube of the time in transit.  In twice the time, eight times as many stars will "hear" us.  If they are listening.  Tens of thousands of stars now reside inside our "radio sphere."  Given another few decades, the number will reach into the millions.

I've gone on far longer than intended about communications.  Maybe, tomorrow I'll discuss the likelihood of intelligent life even arising.

Phil