What would happen if you turned off Friction?

What would happen?

  • A lot of traffic accidents. Brakes work by converting motion into heat via friction, plus, your hands suddenly just slip along the steering wheel without gripping. Also, your tired are now more like ice skates.
  • Your drink spills off the table. Any non-perfectly flat surface now lets objects slide to the point of lowest gravitational potential energy, usually, off the table.
  • You cant pick stuff up. God didn’t give you fingerprints for the sake of Homeland Security, they increase the surface area of your fingertips and increase friction. Now, everything slips between your fingers
  • Bikes become nearly 100% efficient. Currently, bikes with well oiled and maintained chains can reach around 95% efficiency while pedalling. The remainder is taken up by friction, so smooth pedalling until you try to steer in a different direction.
  • The days on Earth stay the same length. Currently, the friction of the Earth’s oceans being dragged across its uneven surface over time slow down its period of rotation.
  • Nails shoot out of everything like bullets. Nails hold in place because the material around them presses against their sides, producing friction. Now, those forces act against the wedge-shape of the nail head, and the interior of wood-framed buildings turn into a shooting gallery.
  • Any pile of sand or dirt turns to liquid. This includes large hills, some mountains, sand dunes, etc – without friction to prevent the granules from slipping past each other, those sand bunkers look a lot more like water hazards.
  • Everything becomes layer cake. Any aggregate will start to sort itself by density, as denser materials fall through lighter materials towards the bottom. Basically, you get a centrifuged sample without the centrifuge.
  • Land becomes an ocean of quicksand. As mentioned in previous points, any loose material now acts like a perfect liquid, and materials quickly sort themselves by density. Anything not built into bedrock sinks – entire cities sink into their foundations. (see Liquefaction)

In sum, it would be a sticky situation

What would happen if the amount of Oxygen doubled instantly?

  • Paper airplanes now fly further. With all that extra air, the air pressure near the surface increases significantly. Gliders, parachutists, birds and paper-plane hobbyists enjoy greatly improved performance.
  • Everyone gets better gas mileage. Oxygen-enriched air improves engine performance by producing hotter reactions and reducing the proportion of nitrogen, which reduces heat transfer (Page on Energy.gov)
  • Higher elevation Biomes become inhabited by more vertebrates. Areas such as the high Himalayas or high Andes are no longer off-limits to animals without special adaptations to increase their levels of hemoglobin.
  • Insects of unusual size. Many insects rely on gaseous diffusion to for respiration, therefore the maximum body size depends on the proportion of oxygen gas in the atmosphere. Most bugs get bigger, some smaller (seeAtmospheric oxygen level and the evolution of insect body size)
  • Everyone feels more alert, active, and happier. All that fresh oxygen improve our cognition, alertness, and physical performance. As a result, most athletic records would likely be broken by oxygen-enriched athletes.
  • We get sick less often. Neutrophils, soldiers of the immune system, destroy bacteria by using NADP oxidase to pump ions into, and disrupt, intruding cell’s membranes causing rupture. More oxygen, more oxidase. (Page on Nih.gov)
  • We die younger. Free radicals (i.e.  O2-) are thought to exacerbate the aging process through Oxidative stress, which interferes in numerous cellular processes: protein production, DNA replication, intercellular communication, and are also thought to contribute to MS, Alzheimers, Parkinsons, and a host of other ailments.

In other words, we would all burn twice as bright for half as long.

(Note this answer originally appeared as a post on Quora.com, and has received subsequent attention. I can attest that I am the original Author http://www.quora.com/Andrew-Cote )

What would happen if Oxygen disappeared for 5 seconds?

All Oxygen? A few things..

  • Everyone at the beach would get sunburns. Ozone is molecular oxygen, and blocks the majority of UV light. Without it we are toast.
  • The day-time sky would get darker. With fewer particles in the atmosphere to scatter blue light, the sky would get a bit less blue and a bit more black.
  • Every internal combustion engine would stall. This means that every airplane taking off from a runway would likely crash to the ground, while planes in flight could glide for some time.
  • All pieces of untreated metal would instantly spot weld to each other. This is one of the more interesting side effects. The reason metals don’t weld on contact is they are coated in a layer of oxidation. In vacuum conditions, metal welds without any intermediate liquid phase (Cold welding). 
  • Everyone’s inner ear would explode. As mentioned, we would lose about 21% of the air pressure in an instant (~ from sea level to 2000m elevation), so expect some serious hearing loss.
  • Every building made out of concrete would turn to dust. Oxygen is an important binder in concrete structures (really, the CO2 is), and without it the compounds do not hold their rigidity.
  • Every living cell would explode in a haze of hydrogen gas. Water is 88.8% oxygen; without it the hydrogen turns into gaseous state and expands in volume. Molecular weight of Water
  • The oceans would evaporate and bleed into space. As oxygen disappears from the oceans’ water, the hydrogen component becomes an unbound free gas. Hydrogen gas, being the lightest, will rise to the upper troposphere and slowly bleed into space through Atmospheric escape.
  • Everything above ground would immediately go into free fall. As oxygen makes up about ~45% of the Earth’s crust and mantle, there is suddenly a lot less “stuff” beneath your feet to hold everything up.

(Note this answer originally appeared as a post on Quora.com, and has received subsequent attention. I can attest that I am the original Author http://www.quora.com/Andrew-Cote )

How big are we compared to time, or space?

Perspectives

Let’s put things into perspective. It’s important to realize that regardless of how wound up we become in our individual lives, in our hopes, dreams, struggles and concerns, we take place in a much larger picture that determines most of our lives. Our families, our nations, our cultures and civilizations – there is a large background to everything we do that is often obscured, blocked out by our narrowly evolved attention and limited focus. In a society of millions, in a culture of tens of millions, in a civilization of hundreds of millions and a world of billions, we live out our lives in relative ignorance of most of what goes on.  This article attempts to give some context to just how, well, big, everything is compared to one of us.

Our place in Time

Humans, in good condition, can live to be around 80 to 90 years – that’s roughly 30,000 days. Presently there are 7 billion other people walking around the planet, and since we all experience time at the same rate, that’s 7 billion human-days per day. Each day on Earth represents 230,000 human life times in terms of raw human experience, therefore even if you live to be 85 years old you’ll hardly experience a millionth of a percent of what goes on among humans on Earth in a single day. This is just current events; things get bigger if we look backwards.

50,000 years ago lived a couple from whom the entire human race descended (we know this through Mitochondrial DNA – google it). Since then, in all of our history there have been 107 billion humans that have walked this Earth.[1] That means right now, only 7.5% of the human population is alive. How many days have been lived over the course of history? Naturally this depends on the size of the population and life expectancy[2], which both change over time, but using a weighted mean we can figure out that since our Mitochondrial Adam and Eve there have been just shy of 6 trillion years of human life lived, or about 20 years of human life for each star in the Milky Way Galaxy.  In our 85 year life span, we experience seven trillionths of a percent of all of human history. And you thought you could keep up with things on twitter. Looking beyond the Earth is even more humbling, or depressing, depending on your outlook.

The Universe began 13.7 billion years ago, which means us humans as individuals have lived, in aggregate, over 400 times longer than the Universe we inhabit. If we imagine the whole history of that time as a single calendar year[3], splitting those 13.7 billion years into 12 months so that the Big Bang is at 12:00am, January 1st, and the present is midnight, December 31st, where do we come along? On this timeline, the Milky Way Galaxy forms around May 11th, and our own Sun first starts shining in the beginning of September. By October the Earth is teeming with photosynthetic life, but its not until December 14th that we see simple animals arise. Us humans have to wait until December 31st,  2:00pm, before we come on the scene. When does our recorded history start, wherein began every tradition, invention, poem, and story that make up the roots of our cultures? 15 seconds to midnight, December 31st. All of the Enlightenment, modern science and technology, human rights and democracies, everything that defines the present-day world began at 23:59:59, 1 second to midnight. Our time as individuals is utterly dwarfed by both the past that has come before us, and the magnitude of the activity around us. We cannot hope to experience it all, so spend your time wisely.

Space

Space is a different story. Accessing space is much more difficult than time: we have the benefit of travelling through time even when we’re standing still, which means we can cover a good distance by not moving. To travel through space you need to move, however the faster you travel through space the less you travel through time. The conversion factor between space and time, or the “exchange rate”, is the speed of light: if a person travels at that speed through space their travel through time stops completely; likewise if they stand still they travel through time at the speed of light (also called “C” for celeritas, the latin word for swiftness). Space, and time, are both measurable by the same quantity, C, and our travel through either can never exceed C.

In practice, the space we can access is largely 2-dimensional. We live on the surface of a planet, not in the sky or in the sea, in which case our living space would be much more 3 dimensional. Yes, we can walk up stairs or on to a plane, however our range of movement is confined to flat surfaces that we can stand, walk, or maybe jump on. Intuitively this sounds odd, but of all the volume of Earth (all 3 x 1024 mof it), the most we can access by running around the surface is a spherical shell extending from the ground to however high you can reach, probably not much more than 2 meters (a volume of 1 x 1015 m3 for comparison). In other words, as surface-crawling creatures we can access about a billionth of the volume that counts as our planet, atmosphere and all.

Some might argue we don’t need to be someplace to access it. We can use a video camera, or microphone, or long stick to get the sensory experience of a remote location. In that case, the range of space we can access is limited by how fast we can send electronic signals, which of course travel at C. If we want to experience relevant events, i.e. events that occurred while we are alive, we couldn’t receive signals from a distance further than our lifespan in light years  If we live to be 85 years old and get a signal that originated 90 light years away, that signal was sent 5 years before our birth. Our “accessible space” volume is now a sphere with radius of 85 light years. How does that compare with what’s out there? Of the 400 billion stars in the Galaxy about 70 are within our life-time accessible sphere, which is ten millionths of the total. With a radius of 46 billion light years, the fraction of the universe we ever experience is comparable to the size of a proton relative to a light year. In other words, the space we can hope to reach is utterly insignificant compared to the total there is.

Conclusion

Some may come away from these numbers a bit depressed, others, a bit amazed. In our efforts to stay connected, be informed, up-to date, well travelled or well-read, we are always comparing ourselves to our peers and what we think of as the potential out there. Keep in mind that no matter what you do, it is only the barest fraction of a percent of all there is. We are far better off focusing on making meaningful lives as individuals, and cultivating experiences that are rich and of high quality, than trying to be the greatest, do the most, see everything, or be everywhere at once. It is simply impossible, and once begun the process of comparing ourselves can only lead to disappointment and dissatisfaction.

 

 

 

 

 

 


[1] http://www.prb.org/Articles/2002/HowManyPeopleHaveEverLivedonEarth.asp

[2] http://en.wikipedia.org/wiki/Life_expectancy#Life_expectancy_variation_over_time

[3] http://en.wikipedia.org/wiki/Cosmic_Calendar

Cat Physics: Drinking Milk

For thousands of years cats have held sway over the hearts of mortal men. In Ancient Egypt, cats commanded the pharaohs to erect massive temples and pyramids at the cost of thousands of slaves’ lives and most of the Empire’s wealth. During Hellenic Greece, cats manipulated Pericles, the heroic king of Athens, into waging the First Peloponnesian War in a bid to capture more pastureland for milk-producing cattle from the Spartans, who were strictly vegans. Today, cats and cat-related images, videos, and memes are a multi-trillion dollar business – in 2010, the monetary value of cat-related internet traffic exceeded the gross GDP of all G20 nations, combined.

In all the centuries of close companionship with these fur-coated comrades rarely has the question been asked: how is it cats drink with such poise and grace? Often it has been naturally assumed that cats possess Aphrodite-like feline prowess which seduces milk onto their tongues, demonstrating once again that cats are exempt from the laws of physics.

Image

This cat knows that mass times acceleration equals delicious.

However as researchers from MIT, Virginia Tech, and Princeton have uncovered, it takes more than just a feline to drink like a cat –  in fact, it takes subtle knowledge of the laws of fluid dynamics.  In the process of lapping up a tin of milk cats balance perfectly the forces of adhesion, fluid cohesion, gravity and inertia: enough mathematics to give any undergrad paws for consideration. As a cat drinks, it extends its tongue fully to curl back on itself like a capital ‘J.’ The exposed top surface of the tongue then just barely touches the surface of milk, before speedily snapping back. As the tongue retracts the milk adheres to its surface, drawing up a column of milk which the cat then deftly closes its mouth on.

awesome,cat,milk-583f5c4cbeb83ab4d80a4f9e2ca498df_h

Fact: The cats in this picture know more physics than the average MIT undergrad.

The process is similar to quickly removing one’s foot from the bathtub – the faster you remove your foot, the more water flies up to follow it. Cats take advantage of this in a very clever manner by using the adherence of fluids to their tongue to draw up a column of fluid and into their mouths, but choosing the right speed gets tricky. A column of fluid can be drawn up and stay intact in the first place because of most fluids’ high internal cohesion, or “self-stickiness.” Lapping at just the right speed balances the pull of gravity with the internal pull of cohesion and adhesion to the tongue – any faster and the cohesion would be overcome, sending milk flying, any slower and gravity takes over pulling the milk back down before kitty can take a sip. More technically, the acceleration of milk adhered to the cats tongue must be less than the milk’s internal friction coefficient. The keeps the accelerated milk’s “drag,” or force of inertia, weaker than the “pull” of inter-molecular  electrical attractions (or inter-milklecular attractions, as the case may be) which cause cohesion.

Now if you’ve ever thought bigger cats can drink faster than smaller cats, congratulations, you might just be wanted at Princeton’s Department of Mechanical and Aerospace Engineering. A member of this department and co-author of the article, Jeffrey Aristoff, noted that the increased surface area of a larger cat’s tongue increases the tongue-fluid adhesion, enabling it to take greater gulps with each tongue-full. With more fluid comes more inertia, however the internal cohesion stays constant. As a result, bigger cats with bigger tongues must drink slower or have a lower “laps per minute1” to keep their sips clean and fur-coat picture purrfect. Aristoff, remarking on the study, concluded, “our research… suggests that the cat chooses the speed in order to maximize the amount of liquid ingested per lap… This suggests that cats are smarter than many people think, at least when it comes to hydrodynamics.” Lion’s don’t just take their time out of pride – they also have PhD-level knowledge of fluid dynamics on how to drink without spilling a drop. Thanks to unconventional applications of hard science, that secret’s out of the bag.

Interestingly, the laps-per-minute rate for a cat of this size means it takes a hell of a long time to finish one glass of milk. Long after our Sun has turned into a red giant and consumed the Earth, erasing all signs of humanity in an incandescent fog of plasma, this cat will be 3/4 finished.

With this new understanding, how long will it take this tiny cat to finish its milk? Long after our Sun has turned into a red giant and consumed the Earth, erasing all signs of humanity in an incandescent fog of plasma, this cat will be 3/4 finished.

1. More specifically, the laps-per-minute is proportional to the 6th root of a cat’s mass.

Sources:

Reis, P. M., Jung, S., Aristoff, J. M., & Stocker, R. (2010). How cats lap: water uptake by Felis catus. Science330(6008), 1231-1234.

Water on Mars

Mars presents arguably the best location to for humans to make the first steps in colonizing space, not least of all for its abundant reserves of water.

Mars has a considerable but modest atmosphere, so that its inhabitants probably enjoy a situation in many respects similar to our own. – William Herschel, 1784 address to the Royal Society

One year ago, on November 26th, an Atlas V Rocket took to the skies from Cape Canaveral, Florida, sending on an escape trajectory 4 metric tons of scientific payload. As the rocket booster lurched ponderously towards the sky under 136,000 kg of thrust, one more robotic explorer joined the ranks of those who would map the solar system on behalf of mankind – first and foremost, to see what’s there, and second, to see if we are alone. Half a billion kilometers later, last month the Mars Science Laboratory – nicknamed Curiosity – touched down successfully on the Martian surface, to carry out its eponymous mission of exploration and discovery. Its primary objectives, to study the climate and geology, to search for signs of life, and thirdly, to further analyze the presence and role of water on Mars.

The history of the discovery of water on Mars is at once a history of our capacity for exploration as well as a history of the human imagination. Since ancient times the Planets, meaning wanderers in Greek, have captured our attention for their ability to move across the night sky whereas all other stars remain fixed. Planets were not known to be anything other than points of light until Galileo’s telescope revolutionized our perspective in 1609, which revealed that planets are places, as real as the Earth. Surface features of Mars were first mapped by Dutch Astronomer Christiaan Huygens in 1659, who also discovered Saturn’s rings. Huygens observed a dark spot on the surface of Mars and thought it water, and so named it Syrtis Major, after the Roman name for the Bay of Sidra on the coast of Libya. In reality, it is a series of valleys and impact craters, however in 1719 Maraldi observed that Mars has polar ice caps much like the earth, which have since been found to be mostly water ice.

Water on Mars first gained international attention in 1877, when Giovanni Schiaparelli noted the appearance of straight lines on its surface. He called these Canali, Italian for grooves, which was mistranslated into Canals in English. British astronomer William Herschel jumped upon the idea of canals on Mars, and wrote science fiction for the public describing an ancient and noble race constructing massive irrigation projects in a desperate bid to channel water from the polar caps to the desertifying latitudes. Canali were shown to be optical illusions as more powerful telescopes developed, but the seed of wonder at Mars was instilled in the population at large and remained rooted in science fiction and public imagination for generations to come.

Exploration and Evidence

The Vallis Marineris would have taken tens of thousands of cubic kilometers of flowing water to carve

In the modern era of space exploration Mars is by far the most visited of the other worlds, some 50 missions have been attempted yet only 21 have been successful. Of those attempts, Americans have launched 20 missions, the Russians 19, the European Space Agency (ESA) has sent two 2, and British, Japanese, and Chinese one each. The first spacecraft to orbit another planet, Mariner 9, entered Martian orbit in 1971 on a mission of surface photography. For the first time in history the detailed terrain of another planet was seen by human eyes: river networks, valleys, volcanoes, even weather fronts and fog. Though arid and lifeless, it was unmistakably similar to the Earth. Subsequent orbiters have substantiated these first impressions with detailed maps showing evidence for rainfall patterns, seasonal variations in ice coverage and massive aquifer (underground lakes) outflows. The largest of these outflows carved a canyon 25 kilometers wide and hundreds of meters deep, requiring a flow of water 10,000 times that of the Mississippi River.

Networks of valleys resemble those made on Earth by rainfall patterns

Surface missions to Mars began in 1976 with the Viking probes, which reported further evidence for water flooding, deep valley erosion, and estimated a soil water content as high as 1% by volume. Mobile surface robots, named Rovers, landed on Mars in 1997, twice in 2004, and again in 2012. Of these rovers two are currently operational, Opportunity and Curiosity. Rovers both qualified and elaborated on the initial findings from the orbiters and landers. Namely, atmospheric pressures are far too low and cold for surface liquid water, but highly salty water might exist in liquid form meters below ground. Additionally, there is evidence for hot springs bringing material up to the surface, and last month Curiosity sent back photographs of smoothly worn pebbles like the kind found in riverbeds showing that,  at some time in the past, Mars had rivers that flowed for hundreds of years.  Most notably, in the southernmost and northernmost one third of the planet, the top 10 meters of soil is as much as 50% water ice by volume, meaning a person’s daily water needs can be satisfied by a small bucket worth of Martian soil.

How much water?

An estimate of the total water on Mars, carried out by the Odyssey orbiter mission in 2001, is roughly twice the volume of Lake Michigan, or about 10,000 cubic kilometers of water. For comparison, 10,000 cubic kilometers was the estimate for total Arctic sea ice in 2010. The finding that Mars has as much water as there is Arctic ice on Earth might surprise some who imagine Mars as a dry, arid place, but evidence points to there being even greater amounts of water in Mars’s past.

Indeed, many planetary scientists argue that expansive oceans were once a feature of Mars. The geography of Mars is dramatically split between Northern and Southern hemispheres. The entire North is thousands of meters lower than the South, thought to be due to a massive impact early in Mar’s history. Along the boundaries between South and North, numerous sites show evidence of ancient shorelines and erosion. This ocean hypothesis is also substantiated by the direction and level of erosion of valley networks, showing rain that fell close to the North and returned through rivers.  An ocean matching the shorelines found would, in fact, cover 75% of the surface of Mars. Such an ocean would have had some 60,000,000 cubic km of water, an amount to fill the entire Mediterranean Sea 20 times over. If Mars once had water in such abundance, where is it today?

The history of Martian water

To understand where Mars’ water has gone, it’s necessary to understand two features of the Martian climate – its air pressure, and temperature. Currently temperatures average -40°C on Mars and atmospheric pressure is roughly 0.6% of Earth’s. As a result, any exposed water quickly freezes then evaporates directly into a gas, and once in the atmosphere is struck by radiation from the sun and split into Oxygen and Hydrogen.  The Oxygen reacts with iron minerals in the Martian soil, rusting together and giving the planet its reddish color. The Hydrogen, being lightest of all elements, rises high into the atmosphere before being blown off into space by the pressure of the Sun’s light. Every second, some 5 – 6 kg of Martian atmosphere is forever lost to space. On Earth, a powerful magnetic field protects our atmosphere from the Sun’s radiation, and organic processes continuously renew the supply of highly reactive oxygen.

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Over billions of years the supply of water on Mars has frozen, killing the planets ability to retain heat. As the water ice slowly separates into hydrogen and oxygen the hydrogen is blown away into space by solar winds, while oxygen binds to iron in the crust rusting the planet into its current reddish hue.

The water we see today on Mars is just a tiny remainder from the past, the leftovers of a world-wrapping ocean. Many scientists believe the Martian atmosphere was once as thick as the Earth’s, composed mainly of CO2. A thick atmosphere of CO2 is important for planetary water cycles, as the CO2 traps heat from the sun and the thick atmosphere allows water to be in liquid form, but also acts as a resevoir of heat preventing drastic swings in temperature from night to day. Over great periods of time, CO2 binds to rocks to form carbonate minerals. On Earth these carbonates are washed down from dry land onto oceanic plates, which slowly subduct beneath the continents and form volcanic mountain ranges through heat and friction. Volcanoes release this CO2 back into the atmosphere when they erupt, completing the CO2-rock cycle.

Mars, however, has only one-tenth the mass of the Earth, and therefore much less internally generated heat. Less heat means less active movement of material within the planet’s mantle, preventing the formation and movement of tectonic plates and thus the formation of new volcanoes. Without volcanic renewal of CO2, the atmosphere of Mars slowly settled into the ground, forever trapped in a static geology. As CO2 decreased the temperature dropped, eventually low enough for the great world ocean to freeze completely. When the ocean froze it turned white, and began reflecting most of the Sun’s light back into space. Temperatures plummeted, so much so that most of the remaining CO2 atmosphere froze into dry ice, and snowed itself on to the poles where it remains today. Without any atmosphere and hardly any heat the frozen world ocean began evaporating into space, its Hydrogen component blown away by stellar winds and the Oxygen rusting with iron in the soil, which gives the planet its ruddy hue. The Mars we see today is a frozen, airless shadow of its former self, the lifeblood of its hydrosphere lost to space or else absorbed into endless dunes of red sand

A one-way street?

As mentioned, the great majority of Martian water is locked up in the soil along with the entire CO2 atmosphere. Much of the atmosphere and water are in the form of ice crystals that, if heated, would readily evaporate back into gas. Once the CO2 evaporates into the air it again traps the Sun’s energy, raising the temperature and releasing more CO2, and so on in a reinforcing process. Warming Mars by as little as 7°C could kick-start the whole hydrosphere and climate, though the best method for doing so is hotly debated. Among the possibilities

• Hundreds of square kilometers of mirrors in orbit to reflect sunlight on to the poles, melting the CO2 ice and artificially keeping temperatures high

• Launching thousands of robotic factories that belch a continuous stream of pollution chemicals – precisely the same substances that are killing life on Earth could make Mars suitable for life in the future

• Drilling deep under the frozen soil and detonating hundreds or thousands of thermonuclear warheads to melt the permafrost. Over centuries radiation in these areas would fall to safer levels.

• Dragging asteroids made of frozen methane, nitrogen, and water ice into extremely close approach orbits. Even with a sparse atmosphere, speeds of 30km per second would quickly vaporize this material into a ready-made atmosphere.

Whatever the route may be, Mars has all the elements we need – carbon, iron, sulfur, phosphates, nitrogen, and an abundance of water. Mars is ready to receive us; the technology required is within our grasp. The only question remains is, are we ready for Mars?

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Raising temperatures by as little as 7 K could release substantial CO2 deposits into the atmosphere, kickstarting a positive feedback loop that might eventually make Mars a habitable, warm, and water-laden planet once more.

 

Lower bound estimate for when the universe first developed life

We have all heard that life formed some 4 billion years ago on the planet Earth. But, the universe is some 13.7 billion years old. A lot of stuff could have happened in that intervening 9.7 billion years – could life have happened?

My guess is, yes. Here’s why. The main bottleneck on the formation of life is the abundance of heavy elements, or anything heavier than hydrogen. Metals are formed in stars as they slowly burn through their supplies of H and He and fuse them into more potent stuff, meanwhile lighting up the sky. At the end of a star’s lifetime it can explode in a supernova, releasing all of its fused metals into space, which later go on to form new stars and new planets (re-use, re-duce, re-cycle). Our own star is likely a 3rd or 4th generation roach, which makes sense, because the inner rocky planets are all very rich in metals, a balance of wealth that takes most middle-class white collar stars 5 – 9 billion years to save up.

Meanwhile, a small percentage of stars are super massive and accumulate a wealth of metals extremely quick (the 1%) – in as little as 1 million years. These stars are so massive their gravitational compression accelerates the rate of fusion, and they burn bright and die young like that kid from Home Alone’s career. Even more importantly, these stars go out with a real bang, spreading their fused metals far across space. Although galaxies didn’t form until some 1 billion years after the Big Bang, the first stars may have formed as early as 100 million years on. So, if the universe is a home-cooking project (ingredients: just add hydrogen), how long before we start seeing some life?

Several generations of very massive, very bright, very fast-fusing stars could have formed after 100 million years. It’s likely these stars were big – there was a lot of hydrogen just laying around, doing nothing, just waiting to come together and get lit up. If all of these stars were in the same cluster, they could have lived and died in rapid succession, producing a nebula of gas extremely rich in metals in as little as 150 million years after the Big Bang.

150 million years is peanuts compared to 13.7 billion years, and things only pick up from there. Within this nebula of gas, as stars explode they send out shockwaves which compress the dispersed metals and gas in the nebula into spinning, gravitationally bound regions of material. As this material falls in on itself it flattens out, producing a ‘protoplanteary disc’ (its a pro at making planets) in as little as 100,000 years, with a bulge in the center that condenses into a star. For the next 50 million years the star is in the T-Tauri phase, meaning it is not actually fusing elements yet but just emanating heat and light from contracting gravitationally. This is a very violent period, as dust clumps into rocks, rocks smash into each other and the whole disc of gas is fried by very high energy radiation.

During this terrible-teenage T-tauri phase, baby planets (planetisimals) are forming, and in our own system, after 10 million years planets more distant than Mars were already 3 – 4 times the mass of Earth. Recent research suggests most of the amino acids that make up life formed in the orbiting gas during this period as the intense radiation caused various elements to react and form more complex compounds. Now, inside the forming planets are elements that are radioactive, which slowly release heat by spitting out fast moving particles whenever they feel like it. Most of Earth’s internal heat comes from these radioactive elements. Also bound up in these rocky planets is substantial amounts of water ice, which is generally abundant in space and one of the most common compounds out there.

So, there we have it, all the necessary conditions for life – rocky planets with water-ice locked up in their crusts, melted into liquid-water by radioactive decay, giving a place for amino acids to react, combine to produce long strings of proteins, and these combine to produce RNA, or DNA, or Adam and Eve, if you’re into that. And how long to go from the basic ingredients – water, amino acids, heat, some chemicals – to reproducing microbacteria? Some scientists say as little as 10 million years.

Add it all up and thats less from 170 million years, from start to finish, from Big Bang to Bacteria. Not bad, if you consider on Earth 170 million years ago we already had newts, salamanders, and Satan was just starting to plant dinosaur bones.

References/ Further reading:

http://www.scientificamerican.com/article.cfm?id=the-first-stars-in-the-un

http://astronomy.nmsu.edu/tharriso/ast110/class19.html2

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19980209932_1998078963.pdf

Thierry Montmerle, Jean-Charles Augereau, Marc Chaussidon (2006). “Solar System Formation and Early Evolution: the First 100 Million Years”. Earth, Moon, and Planets (Spinger) 98 (1–4): 39–953.

Moskowitz, Clara (29 March 2012). “Life’s Building Blocks May Have Formed in Dust Around Young Sun”4. Douglas N. C. Lin (May 2008). “The Genesis of Planets” (fee required). Scientific American 298 (5): 50–59.5.