Tuesday 31 May 2016

Life explained by a comet

Kathrin Altwegg and her team have discovered the building blocks of life on a comet. This can be evidence for a theory about how life on earth arose.

A comet and his friend
One and a half year ago, space probe Philae landed on a comet. To be specific, comet 67P/Churyumov-Gerasimenko. This was the first time space engineers landed something on a comet. It wasn’t a perfect landing, however. The probe bounced of the comet a few times, because there isn’t much gravity to pull the lander down, since the comet is very small. Fortunately, the engineers managed to secure it, although the lander ended up just behind a mountain, making its solar panels practically useless, because of the shadow. This made sending data to earth very difficult for the probe. But after many struggles, it has made an interesting discovery.

The Lego blocks of life
Philae has found the building blocks of life in the tail of the comet. The lander has found amino acids, that make up proteins, like Lego blocks make up a Lego house, which are essential for life. But also phosphorus, which is a component of, among others, ATP, a chemical which is very important for managing the energy levels in your body. These building blocks alone don’t make life yet, of course. But these amino acids and phosphorus can tell us something about how life on earth arose.


Brought by comets
The panspermia theory is strongly supported by this discovery. This theory states that these building blocks of life were formed in space and after that become part of the nebula around the sun from which earth and the other planets were formed. Later, the amino acids, phosphorus and other chemicals would rain down on the planets, and delivering the building blocks to the planet. Since earth had a good environment for life, so one thing led to another, and life on earth arose. There is, however, no way to know for sure that this is the correct theory. There are many theories about how life arose, both scientific and religious. But this discovery really supports this the panspermia theory.


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Saturday 28 May 2016

It's cold on Mars

‘These results provide evidence for a recent ice age on Mars.’ say Isaac Smith and his team in this week’s issue of Science. They have discovered this by using radar.

Cold times
Ice ages are periods of time when the climate is exceptionally cold, and because of that, there’s a lot of ice. The last ice age ended 11.700 years ago. Warmer periods of time separate one ice age from another. We currently live in one of those warmer periods and the next ice age probably starts in around 50.000 years. We don’t really know yet how ice ages exactly happen. But we know it can be caused by changes in the earth orbit, which causes the earth to get less light, so less warmth. So it gets colder. An ice age can also be caused by the sun. If the sun is less active for a while, earth also gets colder. Another major factor is the concentration of carbon dioxide and methane in the atmosphere. More of these gasses create higher temperatures on earth. Anyway, ice ages are also a thing on Mars.


Give those little green men a coat!
Isaac Smith and his team have discovered with radar techniques evidence for dramatic changes in Mars’ climate. They have found evidence of ice growing in retreating, in the same way you can also see this on earth; small walls made of dirt that was pushed forward by the ice. They have also discovered that the amount of ice around the north pole of Mars has grown with 87.000 cubic kilometres in the last 370.000 years, which is enough ice to cover the whole planet with a sixty-centimetre-thick layer of ice. Isaac Smith and his team were further convinced by the facts that Mars shares a lot of earth’s traits that cause ice ages. Mars orbits around the same sun as earth, of course, which is one thing that causes ice ages on both planets, but Mars also sometimes changes its orbit, like earth. The changes in the orbit of Mars are even bigger, since the planet doesn’t have a big moon, like earth does, to keep the planet in check.

We can use it here too!
With this discovery, we’ve come to know a lot more about how ice ages on Mars work. Which makes it easier to predict the next one. It also gives us more insight in the sun’s influence on ice ages, since we can observe a planet reacting to the sun, but without many earth’s traits. This new knowledge about the sun can help us in predicting our next ice age. And even in how the greenhouse effect is influencing ice ages.

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Thursday 26 May 2016

Colouring numbers takes up 200 terabytes

Mathematical proofs can be simple or extremely difficult. But they’ve got one thing in common; they are at least a little elegant. Or just consist of 200 terabytes of data.

The computer that did the calculations
Blow up that computer
Two hundred terabytes look like a ridiculous amount of data, and it is. It is enough to fill the hard drives of 441 laptops and the compressed version of the data only takes already 30.000 hours to download, that’s about three and a half years. The supercomputer that ran the calculations needed 2 days, with eight hundred processors running at the same time. Nobody is, of course, going to read the proof, since that is impossible. This gigantic thing also has the world record. The proof took it from another mathematical proof that was ‘just’ thirteen gigabytes big.





The first 7824 numbers with their valid colourings, 
the white squares can be either colour
Checking everything                 
But for what could you possibly need so much data? Well, the problem is called the Boolean Pythagorean triples problem. It asks the question if it’s possible to give each number a colour; red or blue, in such a way that there aren’t three numbers that fit into Pythagoras’ equation; a2+b2=c2. So when 3 and 5 are blue, 4 has to be red, because 32+42=52=9+16=25. As it turns out, to the number 7824, numbers can be coloured in a ‘valid’ way, but after 7824, not anymore. Up to 7824, there are 102,300 possible colour combinations, that's a 1 with 2300 zeroes. Fortunately, Oliver Kullmann and Victor Marek, the mathematician who found the proof, could slim the amount of combinations the supercomputer had to check to just under a trillion.

Where does maths end?
After this proof, a new question arose. Is this really still maths? A lot of mathematicians think otherwise. Because nobody knows why it’s possible to create double-coloured triplets under 7824, but not above. Nor does anyone know what’s special about the number 7825 that it ruins everything. Terence Tao proved the former world record problem, which needed thirteen gigabytes of data to proof, in the ‘old-fashioned’ way, so by reasoning and thinking logically, a year after the computer proved it. Many mathematicians consider that a much more satisfying way and thus the search for the proof of the Boolean Pythagorean triples problem isn’t over yet.

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Monday 23 May 2016

Don’t let our cities turn into junkyards!

More and more people live in cities. And this is not going to change in the foreseeable future. But what are the consequences of this growth for the environment in cities?

Cities in distress
For the past half century, the development of cities has been mostly focussed on improving the economy and creating more jobs. With four billion people currently living in cities, and this number is predicted to have grown with another two and a half billion by 2050, this focus has to shift to keep cities safe and healthy. Currently, many cities, especially the ones with more than ten million people, like Tokyo or Mumbai, struggle with air pollution, poor water quality, waste-disposal difficulties and many more problems. With the amount of people that live in cities only growing, this will only get worse in the future.

Forest in the city
To tackle these problems, urban ecologists, people who study the ‘nature’ in cities, for example the plants and the animals that thrive in a city, are trying to find ways to make cities healthier. With the knowledge these ecologists have gathered, they’ve been able to find ways to make cities more livable. Urban ecologists in Melbourne, for example, are building a forest in the middle of the city, to make the city more healthy and resilient. Other cities around the world, like London, Singapore and Portland are copying this strategy.


Take action!
Although our knowledge about urban environments have greatly improved in the past three decades, there’s still a lot of advances to make. Not only do we need to discover the causes of the problems megacities are facing, we also need to turn this knowledge into action that can actually help distressed megacities. And these advances in urban ecology are needed quite fast since the amount of people in cities is only growing, while the life standards in cities only decrease.

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Friday 13 May 2016

Chinchilla guts mess up biology

Scientists have long thought that cells can’t live without their powerhouses, but Anna Karnkowska and her team have disproven this. They’ve found a single-celled organism, without these powerhouses, in the guts of a chinchilla.

Simple vs. Complex
All living things can be roughly divided into two groups; simple cells and complex cells. Bacteria are made out of a simple cell, which is also called a prokaryotic cell. These cells don’t have any specific parts which fill out specific functions. Everything is just some sort of mush of things you can find inside a cell. The complex cells, or eukaryotes, which animals, plants and fungi are made out of, on the other hand, do have these specific parts. There are many different types of these parts, which can perform many different functions. Plants use these parts for photosynthesis for example, while animals use other parts to be able to produce more energy. These parts are called mitochondria. Scientists have thought for a long time that no complex cell could live without these mitochondria. Like we can’t really live without our power plants, complex cells can’t either. But this is proved wrong by Anna Karnkowska and her team.

Hiding in a chinchilla
They have found a single-celled organism in the guts of the chinchilla of one of team members, that doesn’t have mitochondria. This organism is called Monocercomonoides. There are many organisms without mitochondria, but those are all prokaryotes, or simple cells. The odd thing about Monocercomonoides is that it has all the other traits of a complex cell. It has, for example, a specific place to store its DNA, so it is a complex cell, or eukaryote. The researchers also have already found an explanation for Monocercomonoides’s lack of mitochondria. Since it lives inside the guts of a chinchilla, there are already plenty of nutrients around, so the cell doesn’t need any fancy energy supply. And because it doesn’t need it, the cell hasn’t.

Messed up definition
But what does this mean for the complex cells? Most importantly, the definition of eukaryotes, or complex cells, is strongly dependent on mitochondria. Before this discovery, the definition of a eukaryote was ‘a cell that has mitochondria’, which now isn’t correct anymore. “We overturn this definition.” said Anna Karnkowska in Science. This once again shows that science is constantly changing and is never truly finished.

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Wednesday 11 May 2016

Sleeping with your phone

Smartphones are huge distractions when you try to sleep. Though this is the case, people have actually used smartphone apps to track sleep durations in many countries. One way is an app called Entrain. Using the app, Olivia Walch, Amy Cochran, and Daniel Froger were able to gather data on the sleep schedules of people.

Sleep is important
People are getting less and less sleep. We are distracted by work, social media, and the internet. This can affect our health negatively. If you don’t sleep enough, over time you increase your risk of getting a stroke, heart attack, high blood pressure, and obesity, among others. Olivia Walch et al. invented ENTRAIN to find out how sleep deprivation can be avoided.

Sunlight helps you sleep
They also found out that people who spend more time outside tend to go to bed earlier than people who spend their whole day inside. Even being out for 30-60 minutes improves your internal clocks, helping you sleep earlier than if you were inside the whole day.

Just go to bed early!They discovered that it’s not the time we wake up that predicts how long we will sleep, but the time we go to bed. This means the odds of you having a good night’s sleep aren’t affected by your morning schedule, but your nightly schedule. You sleep more if you don’t sleep late!

One and one is two
With this knowledge, it’s quite easy to ‘solve’ the sleep deprivation problem. If people spend more time in the sunlight and go to bed earlier, they will sleep longer and be healthier in general, considering all the health benefits of sleep. If we all try to get out more and go to bed earlier, humanity as a whole can become healthier and more productive. This is what the researchers tried with their app. ENTRAIN provided the users of the app with recommended bed times based on their age, gender, location, time spent outside, and other factors. All that advice with an app on the biggest sleep-killer in the world: the Smartphone.

Monday 9 May 2016

Your goldfish's quirk is real

If you own a pet, you’re probably convinced that it has its own personality. However, science isn’t convinced. Animal personalities are seen as “goofy, frivolous, and the purview of overly sentimental dog owners.”, but this begins to change.

Personalities were forgotten
For a long time, personalities of animals were filtered out in research results. If, for example, a scientist studies a group of rats, and he or she wants to know how much they eat, the scientist measures how much food every rat eats for a couple of days, and then averages the results. With this method, you can’t trace back the individual preferences of the rats, and thus you can’t study personalities. This is why it has been thought for a long time that personalities in animals didn’t exist.

Be bolt and eat the food!
Andy Sih, one of the pioneers in researching animal personalities, first noticed it in salamanders. While some of the salamanders hid as bird, which eat salamanders, fly by, others didn’t seem to react. Sih found this behaviour odd, since only the salamanders that protect themselves the best from the birds should survive. Like Charles Darwin already discovered. But then Sih realized that the salamanders that didn’t hide also had an advantage. They have more time to swim around and hunt for food than the ‘scared’ salamanders, since they didn’t hide behind rocks so much. When the ditch where the salamanders lived in would dry out, the ‘courageous’ salamanders would have more chances of surviving, since they are bigger because they’ve eaten more.


Shy bird gets the worm
Niels Dingemanse, of the University of Munich, and his team have discovered a similar thing in great tits. They found out that aggressive birds in the group don’t thrive as well as the more timid and docile birds when there isn’t enough food. This may sound weird, but the team has a good explanation for it. When there isn’t much food, aggressive great tits get all wound up in fights about the food. This takes up a lot of energy. While the more timid birds don’t fight and use way less energy for that, although they may eat a little less. An interesting thing however, is that this principle has already been seen in humans. This means that we are now not only able to observe personalities in animals, but these studies may also learn us more about human behaviour and personalities.

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Friday 6 May 2016

Watch out! Paint flake coming in!

An ever increasing amount of space debris is orbiting earth. This can cause some serious problems. ‘New tools are necessary to deal with more than hundred thousands of space debris’ says Alexis Petit in Advances in Space Research.

All know space debris 
Space is a junkjard
Space debris is all the stuff that’s left behind by space missions. This can be everything from tiny screws to whole rocket stages - and everything in between, like a toolbox that was left behind by an astronaut while working on the ISS. Although hitting a rocket stages doesn’t sound nice to anyone, tiny screws seem less damaging. The problem is, they can cause your rocket quite some harm too. Space debris orbits the earth with around twenty-eight thousand kilometres an hour. This is faster than a bullet. A piece of space debris the size of a marble would hit you with the force of a bowling ball going four-hundred eighty kilometres an hour.  For this reason, NASA keeps track of all more than twenty-one thousand pieces of space debris. But they estimate that there are more than hundred million pieces of space debris, most of them smaller than one centimetre. If this amount is getting more – and it is -, this might cause some serious problems.

Killed by a marble
For example, cascade collisions can become a real problem if the amount of space debris is going to increase even more. This means the amount of space debris is so big that when two pieces collide, this only increases the risks of colliding. Over time, this can mean that safe space programmes become impossible, because there’s too much debris. Imagine if all we kept all the car wrecks on the high way, at one point it would become impossible to drive there. In space, we’ve almost reached that point. Six space agencies, among them the ESA and NASA, predict catastrophic collisions with space debris happening every five or nine years and an increase of thirty percent in space debris in the next two hundred years.

Saving the future
Fortunately, Alexis Petit and Anne Lemaitre have a solution. They want to improve the software that NASA uses to track the space debris. With this improved software, they are going to calculate which pieces of space debris are most likely to collide with others. If we remove the pieces of space debris which are most likely to collide, for example by letting them burn up in the atmosphere, the total chances of collisions, and thus more space debris, decrease. We only remove the car wrecks that lie in the middle of the high way, so other cars can pass safely. This plan can give us a safer space and can keep space programmes possible for many generations to come.


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Wednesday 4 May 2016

Life shaped with a blast

Supernovas are awesome things that only happen very far from earth and don’t affect us, aren’t they? Well, it turns out they do, says Adrian L. Melott in this week’s Nature. But how have supernovas changed life? And will it happen again?

The universe comes with built-in firework
Supernovas happen when stars that are eight times as big as our sun come to the end of their lives. If these stars are going to die, their cores get so heavy that they implode. This implosion creates a huge shockwave, which rips the outer layers of the dying star apart.  This layers then start float around the imploded star, and they form a nebula, like you can often see in beautiful pictures taken by Hubble. The implosion also emits all kinds of radiation of different wavelengths, like visible light, that’s the reason we could be able to see a supernova, if one went off, or radio waves, but also dangerous gamma- and X-rays. The supernova also sends all kinds of radioactive materials into space.

CSI: Supernova
Fortunately, supernovas have never happened so close to earth that we felt any of the consequences of these gamma- and X-rays, or have we? Anton Walnner and his team have found extremely large quantities of a radioactive material in the earth’s crust. Sometimes even 40 times as much as normal. After analysing the radioactive material, they concluded that they must have come from supernovas. Multiple supernovas in fact, which occurred in two spurts; one spurt around two and a half billion years ago and another around seven and a half billion years ago. These supernovas didn’t cause any mass-extinctions, since the last one was 65 billion years ago, when the dinosaurs died. But the supernovas might have had another consequence.

Freezing firework
The last spurt of supernovas was around two and a half billion years ago, and around that time, a new ice age started. Although scientists haven’t been able to prove a connection between supernovas and ice ages yet. It is a fact, however, that the evolution of humans was hugely influenced by this ice age. So we might thank our existence to supernovas.

We’re all gonna die!
The bad news is, however, that those same supernovas could wipe us out again just as easily. A supernova that is twenty-six lightyears away from earth (that’s like nine million years if you wanted to go there by car), could already kill more than half of all life on earth. Fortunately, supernovas that are this close to earth don’t happen very often and it is very unlikely that we will be killed by a supernova any time soon. Oh wait, what’s that bright light in the sky…


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Sources:
http://sci-hub.bz/10.1038/532040a

Monday 2 May 2016

Kepler is alive again, and uses microlensing!

“People scratch their heads about microlensing. This will show the power of the technique, get people excited and involved,” said NASA’s astronomer Calen Henderson in this week’s Science. But what is microlensing exactly? And how can Kepler use it?

The ring of light around the star comes from another 
source behind the star in the middle. 
The ‘gravity pit’ of the star has bent the light.
What is this microlensing you’re talking about?
Microlensing is, like many cool things in physics, a phenomena caused by Einstein’s theory of general relativity. This theory states that mass curves space time, like a heavy rock curves a rubber sheet. This is the reason why, for example, planets orbit stars; they are ‘trapped’ in the ‘pit’ the star made in space-time, like a marble which rolls over the rubber sheet will orbit the rock too, if it has the right speed. But a funny thing is, light is also affected by this ‘pit’ in space-time. Because light is incredibly fast, it doesn’t get trapped in the pit, but it changes direction if it passes a heavy object, like a marble which rolls really fast past the rock. Since light also changes direction if it travels through a lens, this is called gravitational lensing. This effect is of course bigger when the object which acts as a lens, the rock, is heavier, if it’s for example a whole galaxy, because the light gets bent more then. But it is also detectable on a much smaller scale, like with a star acting as lens, or even a planet. This is called microlensing, and that’s exactly what Kepler is going to use.

But what’s Kepler currently doing?
Kepler is a space probe that orbits the sun and searches for planets that orbit other stars. It has already discovered many planets using a method called the transit method. This method uses the fact that a planets throws a little shadow on its star as it passes in front of it. This causes a slight decrease in the brightness of the star. Kepler can detect this and then deduce the size, mass and other things of the planet. Kepler has already discovered many planets using the transit method, but there’s a problem. With the transit method, Kepler can’t detect planets which are really far away from their star or planets that don’t orbit a star at all. This is where microlensing comes into play.

So Kepler can use microlensing too?
The effect of microlensing is so small that a ring, like in the picture, doesn’t appear. A star or planet simply can’t bent the light that much. Instead, the star behind the ‘lens’ appears brighter. If a star that has an orbiting planet moves in front of another star that is really far away, the far-away star will become brighter, because the light gets bended by the star’s gravity. But if the planet also moves in front of the far-away star, the planet also bends the light a little, making the far-away star even brighter. 


I feel there might be a ‘but’…
This method is harder to use than the transit method, because it also requires telescopes on earth working together with Kepler. A planet passing in front of its star also happens way more often than a star with a planet passing in front of a far-away star. Kepler will probably discover way less planets with microlensing than it did with the transit method. But microlensing can discover planets that the transit method can’t. Planets that don’t orbit a star can be found with microlensing, but not with the transit method, for example. The reason for this is very simple. You can’t throw a shadow on your star if you don’t have one. Kepler also has trouble detecting planets that orbit their stars very slowly, since the planets won’t pass in front of their star very often and a pattern would be difficult to find. Mircolensing doesn’t have these kinds of problems so it is a great method for discovering planets we couldn’t detect before. This means we can find out even more about the universe!

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Sources:
https://en.wikipedia.org/wiki/Gravitational_lens#/media/File:A_Horseshoe_Einstein_Ring_from_Hubble.JPG