Wednesday, 30 October 2013

The Heat Death of the Universe and Other Horrible Topics for Light Dinner Conversation

We have had a bit of a rough ride this month, learning about the dangers of space. From stars expanding to comet and asteroids crushing us from above we have seen that there is no shortage of potential assassins in this Universe of ours. But what if the Universe itself were to put an end to life? And not just life on Earth, life everywhere. It is not only possible; research has shown that it is downright probable.

To understand what it is about the Universe that all but guarantees an end to life as we and everything else knows it we have to take a physics lesson from a half-crazy, reclusive nut job genius named Isaac Newton. Most people know Newton from the story of him getting beaned with and apple and conceiving gravity as an idea. Most people don’t know that he also devoted a good portion of his life to things like trying to turn mercury into gold and sticking needles between his eyeball and eye socket to see what would happen. But as crazy as he may have been, he was equally brilliant. Beyond gravity, he bestowed upon science the 4 truths about the universe known as the Laws of Thermodynamics.

The fours laws are an article in themselves so I will leave a thorough explanation for another day. What concerns us now is the concept we get from them that is called entropy. Entropy is disorganization. It is the idea that as time goes on the elements of a system that are able to do work get used up and productivity declines. A favourite way to think of it is in terms of a game of billiards (read Bill Bryson's A Short History of Nearly Everything). At the start of the game, the balls are all very close together (low entropy) so it is easy for them to bash into each other and exchange energy. That is why when you break at the start of the game the balls all fly off in every which direction. As the game goes on entropy increases as the organization decreases, eventually leading to a state where you have to plan and target shots over a greater distance to get any work done at all (high entropy).

The Universe is a little bit like that game of billiards. In the beginning, everything was tightly packed together. In fact, all matter was a single point of immense potential energy. The Big Bang is the result of that potential energy and the equivalent of the break at the start of the game. The problem with the Universe is that there aren’t any edges to the table so things can expand forever and the interaction between particles will eventually become non-existent. This is known as The Heat Death of the Universe.

It’s not the cheeriest idea in astronomy but it has been around for a while. Einstein first saw the potential for infinite expansion when he established his Theory of Relativity. He hated the thought so much that be tacked on an extra term to one of this most important equations that fudged the math just enough to reassure him that gravity would eventually stop the expansion and hold everything together. He called it the Cosmological Constant.

Eventually as more evidence came in from work done by Edwin Hubble (who later had a space telescope named in his honour) suggesting that the Universe was expanding at an increasing rate, Einstein came to regret his constant and the wishful thinking it embodied. Modern scientist, however, are re-warming to its use as an explanation for the increasing speed at which the Universe is being flung apart.

The Cosmological Constant is being repurposed to account for the bizarre energy that seems to exist to counteract gravity and push things further and further away from one another. The eventual outcome (don’t worry, this is eons in the future) will be total heat death. The Universe will be an evenly distributed cloud of protons. Cold and impotent in the vastness of space… I guess we better enjoy our cosmic game of billiards while things are still energetic enough to allow it.

Friday, 25 October 2013

Wednesday, 23 October 2013

Comets, Asteroids, and Bruce Willis: The Science of Blunt Force Trauma to the Earth

One thing you quickly learn as you write a suite of articles about space and the dark beyond is that there are a lot of things in the Universe that can kill you. Gamma rays, black holes, solar flares; there is no shortage of topics to make the hair on the back of your neck stand up. There is one threat, however, that is closer to home than all the rest both in terms of distance and presence in the human mind: Impact.

There is something powerfully unromantic about it. Of all the ways the human race could be brought to its knees, a collision by a comet or asteroid is the most blunt and unimaginative. If the Universe were a movie villain black holes and gamma bursts would be the James Bond disaster scenario. Impacts are the celestial equivalent of getting hit over the head with a pipe.

Even still, we stand in awe at the possibility of being hit with such a massive pipe. A plethora of movies have painted varyingly plausible doomsday situations featuring rocks from the sky, and these movies are where most people get their information from. Unfortunately, Bruce Willis and a team of oil drillers aren’t always the best teachers.

There are three places from which falling death can originate. The first, and closest to Earth is the home of asteroids and it lies in the vast track of space between Mars and Jupiter that marks the boundary between the inner and outer solar system. When most people think of the asteroids belt they envision a tightly packed maze of rocks that spaceships must deftly maneuver through with the greatest of care. In truth, it is a pretty roomy place. A flight through the belt is a bit of a letdown in terms of site seeing. Asteroids of any significant size are an average of 5 million kilometers apart. The collisions between asteroids that send them careening onto a path that threatens the Earth are exceedingly rare with an average rock getting bumped once or twice in its several billion year long life. Nevertheless, it happens.

The other two breeding grounds for swift cosmic death are further out in space and are the hideouts of short period and long period comets. They are known as the Kuiper Belt and the Oort Cloud respectively. The Kuiper Belt lies just beyond the orbit of the most distant planet (Neptune) and is home to both comets and planetoids (AKA dwarf planets) like Pluto and Eris. When comets get knocked out of the Kuiper Belt they take on long elliptical (egg-shaped) orbits that pass through the inner solar system once or twice in a human lifetime. These comets are subsequently called “short period comets.” Objects from the Oort Cloud take on much longer orbits and become long period comet. Their orbits can take 1,000, 10,000, or even a million years to orbit the Sun once.

It is all well and good to know where these things come from but the real question is when can we expect one for dinner? It must be said that comets and asteroids are notoriously bad houseguests and you don’t want to be surprised by their arrival. The dinosaurs can vouch for that. It turns out that a sizeable impact happens once every 300,000 years or so with smaller objects burning up in the atmosphere daily or even hourly.

The major impacts are not something you want to be around for. Even a relatively small object (~1 km across) would release a million times more energy than the bomb dropped on Hiroshima and create global chaos. Evidence of past collisions can be seen at meteor crater in Arizona (3.8 km/2.4 miles in diameter), the Chicxulub Crater in Yucatan, Mexico that is believed to have been left by the object that marked the end of the age of dinosaurs (180 km/112 miles in diameter), and in the Sudbury Basin in Ontario, Canada (250 km/160 miles in diameter).

As is evinced by the scale of the holes they leave in the ground, impacts are major events that alter the course of history. It is unclear whether or not humans could survive an event like the one that the dinosaurs faced 65 million years ago, but one thing is certain: Bruce Willis won’t be taking phone calls when we find out that something is on its way.

Saturday, 19 October 2013

Sketchy Fact #11: Death From Above

In 1908 a meteor exploded over Siberia with the force of 1000 Hiroshima-sized bombs. It knocked down 80 million trees over an area of 2,150 square kilometers (830 square miles) and was the largest impact event on Earth in recorded history. Two people died, saying as much about the emptiness of Siberia as the destructiveness of the impact.

Wednesday, 16 October 2013

Terraforming: It’s a nice planet, but we can make it better.

Last week we looked at some of the doom and gloom associated with planets and how they change over time. Things heat up and habitable zones drift away leaving planets both balmy and dead. This week we will try to come up with an escape plan for the human race.

While it is pretty uncertain whether or not humans will exists when the issue becomes relevant, scientists agree that if we plan on surviving indefinitely as a species we will eventually have to leave Earth. So where do we go? We’ve been to the moon so we could set up shop there for a while, but since the moon is tied to the Earth it doesn’t solve much in the way of the sun roasting us to death. We could go to Venus, but moving towards the growing Sun would be equally unproductive. No, if we want a new home the most accessible options will be nearer to the edge of the solar system.

Astrobiologists have proposed three options within our own solar system. Two of them are moons. Titan is the largest of Saturn’s 53 known moons and has an atmosphere similar to what the Earth’s may have been like early in its development. Unfortunately, with a surface temperature of -178 degrees Celcius (-289 Fahrenheit), oceans of liquid methane, and a sky that rains gasoline, the comparisons end there. Europa is our other potential moon-base. It orbits Jupiter once every 3.5 days and is smaller than Titan but, like Earth, it has an Iron core and oceans made of water. The problem is that the oceans are deep enough to cover all the land and they are frozen. While Titan and Europa both have potential, there is only one object in our solar system that is even close to Earth in its current condition, and luckily it’s right next door.

Mars has long been of interest to astronomers both because of its proximity and its characteristics. It is a rocky planet (like Earth) with an atmosphere and evidence suggests that it may have once had liquid water. The problem is, that water is now frozen and as far as we can tell the planet is lifeless. It has an atmosphere that is 95% carbon dioxide and only 0.2% oxygen, but it takes more than poisonous air to squash an astrobiologist’s optimism. Enter terraforming.

Terraforming (literally “Earth Shaping”) is the process of changing a planet so that it can support human life. It sounds like science fiction, and right now is more or less is, but one day it might be just another thing that people do in space. We are already shaping our own planet through the burning of fossil fuels and the release of chemicals into the atmosphere, so why not try it someplace else?

Theorists have proposed three methods we might use to turn Mars into Earth 2.0 and they all focus on turning up the Martian thermostat. They are:
  1. Orbital Mirrors
  2. Pollution Factories
  3. Smashing Asteroids Into It
None of those options is a joke.

Orbital Mirrors (up to 250 kilometers in diameter) would be positioned around Mars to deflect more sunlight at the surface and begin to heat things up. Pollution factories would do what they do here on Earth and pump greenhouse gases into the atmosphere, trapping more of the heat that reaches the surface. Finally, for the impatient terraformer, there is the option of strapping rockets to asteroids that have a high ammonia content, pointing them Mars, lighting the fuse, and running like hell. The impacts would heat the surface by a few degrees each, but leave the planet off limits for a few centuries due to the generally unfavourable state of chaos they produce.

The idea is to warm things up enough for liquid water to begin flowing. From there, bacteria could be introduced to do what they did in the early days of the Earth and convert the atmosphere from almost entirely carbon dioxide to a more congenial mix of oxygen, nitrogen, and greenhouse gases.

The technology and the motivation to change Mars into humanity’s next home are likely many many years away, but as the Sun heats up and Earth gets crowded the red planet may gradually become the apple of our collective eye.

Friday, 11 October 2013

Sketchy Fact #10: Sweeping Up the Stardust

“… Every atom in your body came from a star that exploded. And, the atoms in your left hand probably came from a different star than your right hand. It really is the most poetic thing I know about physics: You are all stardust.” – Lawrence M Krauss

Wednesday, 9 October 2013

Life and Death in The Goldilocks Zone: The Shifting Scope of Planetary Habitability

Have you ever wondered how long the Earth will be able to support life? I don’t mean to suggest that human activity will render the planet uninhabitable (although it might), I’m talking about the natural cycle of the planet and how long it will be able to keep things nice and cozy for air-breathing organisms like us.

According to a recent study in the journal Astrobiology the answer might only be another 1.75 billion years. On first reading you might think I am being pretty liberal with my use of the word “only,” but consider the fact that life has existed on Earth for nearly 4 billion years already. That means that with 1.75 billion years left on the clock, Earth is about 70% of the way through with its hosting duties.

The problem doesn’t have as much to do with the Earth as it does with the Sun. The thing about stars is that they tend to snowball in terms of the light and heat they produce. Young stars start out dim and cool compared to the steamy blinders they will eventually become. Subsequently, as they age their “habitable zones” get further and further away.

We first heard about habitable zones in our discussion of exoplanets but the Coles Notes explanation is that they are the area around a star where things are warm enough for water to be liquid (rather than ice) and cool enough for it not to boil away. More kid-friendly scientists tend to call this space the “Goldilocks Zone” because things are just right.

The Sun’s habitable zone is moving outwards at an estimated rate of 1 meter per year and recent models suggest that Earth is closer to the inside edge than previously thought. The upshot is that in a little less than 2 billion years, the oceans will have boiled away and anything left of Earth will have a pretty rough go of things.

It’s a pretty depressing thought that one day this lush blue-green ball that we all call home will be a blistered chunk of rock orbiting an aging hot-shot star, but it is a fact that humans will eventually have to face if we want to continue existing. Fortunately not all scientists agree about when check-out time might actually be, so don’t start packing up the little bottles of shampoo just yet.

Caleb Scharf, an astrobiologist at Columbia University thinks we might be getting ahead of ourselves. “It’s the age-old problem of over-interpreting a single data point” says Scharf. The fact is, we may not know as much about habitability as we think we do.  There are many factors outside of location relative to a habitable zone that dictate whether or not a planet can support life. Atmospheric conditions, plate tectonics, and the history of life on the planet all have their role to play. This has lead University of Victoria planetary climatologist Colin Goldblatt to comment, “If you want me to build a habitable planet where Venus is, I can do that; if you want me to build a dead planet where Earth is, I can do that.”

That may say as much about Colin Goldblatt’s confidence in his terraforming abilities as it does about the current state of things on Earth, but it gives us some hope. Even as the Sun heats up and the Goldilocks Zone drifts out towards Mars, organisms on Earth may have a bit of extra time to pack our bags and jump ship.

Friday, 4 October 2013

Sketchy Fact #9: The End of Mordor

A species of miniature humans survived on the Indonesian Island of Flores until 12,000 years ago. They stood about 3 and a half feet tall and have been given the common name “Hobbit Man.”

Wednesday, 2 October 2013

Building Lazarus: How to Bring Back Extinct Animals

Humans have an uncanny ability to kill things. Going back as far as the first colonization of the Americas, people have been credited with wiping out everything from wooly mammoths, to giant ground sloths, to passenger pigeons, to the European Aurochs (the ancestor of all domestic cattle). Show us a sky that is darkened with the soaring bodies of millions of majestic birds, and pretty soon we will show you an impressive pile of meat.

Fortunately, a few more enlightened souls are at work to undo some of the steam-rolling of the past. Using any one of several ingenious methods, biologists might soon start filling in the holes in nature that our forefathers carved out with spears and shotguns. It sounds a bit like the plot to Jurassic Park, only more intensely sciencey and, to my mind, even more exciting.

A leading strategy for raising the dead is to take what we know about our target animals and use it to tweak the DNA of living species. The Passenger Pigeon is a good example. These birds didn’t die out all that long ago in the grand scheme of things. Martha, the last known passenger pigeon died on September 1, 1914. Long enough ago that she knew a world without Nazis, but near enough in time that we can still pull viable DNA from her preserved skin cells.

Using that DNA, scientists have reconstructed the Passenger Pigeon genome and are now turning to their closest living relatives, the band-tailed pigeon, for some adventures in genetic manipulation. Using methods that are a bit too advanced for me to adequately explain in a short blog, researchers plan to one day be able to take the DNA of band-tailed pigeons and change the base pairs (adding a adenine here, a guanine there) to produce what will genetically be passenger pigeons. The results won’t be perfect, but nothing in nature ever is. In the words of biologist and de-extinction advocate Stewart Brand, “the results will be close enough.”

If you’re a member of the “close enough” camp, you might also be interested in the case of the European Aurochs, an animal that the first herders used to breed every existing line of domestic cattle before tossing them into nature’s waste-basket. Since their DNA still exists, albeit spread out between a number of different cattle breeds, anyone with a mind to do so could start back-breeding modern cattle and one day (probably quite a long time from now) be herding their formerly extinct bovine brethren.

However, if like me you are more impressed by intensely freaky science experiments, you might prefer the more exact results and bizarre methods used in the cloning of extinct species. Since 1996 when Dolly the sheep first found her way into the lexicon, researchers have been working to take the DNA of extinct species and infuse it into the eggs of living animals in the hopes of producing something shocking. They have actually already succeeded in doing this once.

The Bucardo, a subspecies of Spanish Ibex went extinct in 2000, but in 2003 a baby Bucardo was born using the same methods that produced Dolly. Unfortunately the newborn only survived about ten minutes before succumbing to respiratory failure (a common problem with cloned animals), but scientists are hopeful that as their methods improve so will the lifespan of their  creations.

Similar methods have been used to play god with chickens and endangered falcons. Take some falcon skin cells, reverse engineer them into stem cells, and implant those into chicken embryos and the resulting chickens will effectively have the gonads of a falcon. If you could persuade a male and female "modified chicken" to breed, the birds would lay eggs that hatch into honest to goodness falcons, presumably to the surprise of the hapless and soon-to-be helpless parents.

Cloning extinct animals raises all kind of questions about ethics. What kind of life would these animals have as the only members of their species? How would they learn how to behave if they have no same-species parents? What impact would reintroducing these animals have on presently modified ecosystems? These are all things that need to be considered, but the overarching theme surrounding the topic is hope. If we can find a way to responsibly and successfully bring back animals and use them to restore the world to some of its former glory, it at least seems worth a shot.