Nuclear Fusion and the Stars

Posted on March 19, 2013 by rtjobe

Animated diagram of deuterium (hydrogen-2) and tritium (hydrogen-3) fusing into helium-4, courtesy of Wikipedia.

Nuclear fusion, the process by which two atoms collide to form a single larger atom, has been fueling stars since the beginning of star formation. At most distances apart, two protons will naturally repel each other due to the fact that both are positive charges, and the Electromagnetic force between them pushes them apart; however, all atomic particles will attract one another at extremely close distances (around 1-3 femtometers, or the distance between protons and neutrons in an atomic nucleus) due to the Strong force acting on them. The Strong force can overpower the Electromagnetic repulsion between like-charged particles, but this can only happen at an extremely close distance as the Strong force has a very short range.

What does this mean for nuclear fusion? It means that if you have two separate atoms, it is possible to force them to combine together into a single nucleus provided you can get them close enough for the Strong force to overtake the Electromagnetic one. If the nucleus formed in the reaction is smaller than iron (Fe) or nickel (Ni) then the reaction will produce energy, as the particles can all experience the net attraction from each other particle; for larger nuclei the reaction will consume energy as the produced nucleus will require more energy to overcome the Electromagnetic forces than is supplied by the net attraction of the particles to each other. The only remaining question is, how do the two fusing atoms overcome the Electromagnetic repulsion to begin with? If the two atoms are moving fast enough, their momentum can overcome the repulsion and they will stick once they smash together. Extreme temperatures and pressures can bring atoms such as hydrogen up to speeds fast enough for fusion, making the cores of stars a perfect breeding ground for fusion reactions.

The reaction that takes place within stars is often a proton-proton chain reaction, as is the case with our own sun.  This is a multistage fusion reaction which ultimately converts four hydrogen atoms into one helium-4 atom and an excess of energy.  At first two hydrogen nuclei smash together and fuse while simultaneously releasing a positron; and a neutrino, which causes one of the protons to become a neutron.  This new hydrogen-2 atom then fuses with another hydrogen-1 to produce a helium-3 atom, as well as releasing energy as two gamma rays.  This helium-3 collides with another helium-3 formed by the same process to produce a helium-4 atom while at the same time releasing two of the protons as hydrogen-1 atoms.  Ultimately, six hydrogen-1 atoms become a heliums-4 atom, two hydrogen-1 atoms, and energy released as gamma rays.  A pictorial representation can be seen here.


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Mars Colonization: Would You Go?

Posted on March 19, 2013 by mirandaskunz

Mars Curiosity

A recent survey by the Huffington Post found that 7% of people would volunteer for a one-way mission to Mars. It also found that 15% of people thought it was somewhat or very likely that humans would establish a colony on Mars within their lifetime. If a colony was established, there was a lot of dispute over how the government of the colony should be run. Many people thought the colony should be self-governing, while others thought it should be governed by the U.N. or the U.S. The article also cited another survey by the Phillips & Company for Explore Mars and Boeing that found that 67% of people agreed with the statement “I am confident humans will go to Mars in my lifetime.”

Overall, I found these statistics very interesting. It surprised me that 7% of people would definitely volunteer for such a mission, as I would probably fall into the “I would consider it” category. Although it would be awesome to be a part of such a ground-breaking mission, it would also be incredibly difficult for me to leave behind my family, my friends, and the only life I have ever known here on Earth.

I also thought it was intriguing that the poll considered the type of government that would be in place on the colony, which is something that I had never considered. We do not really have an international set of rules or standards for sending people to establish a colony in a totally new place, so what would we do in that situation?


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Exploring Climate Change in Google Earth

Posted on March 19, 2013 by mirandaskunz

The video below is an introduction to a series of videos that utilize Google Earth to inform viewers of problems involving climate change and global warming. The “tours” can be downloaded here. These tours are very informative and allow the user to pause them to explore the Google Earth content on their own.

I think that this is a great approach for spreading awareness about climate change on Earth and the effect humans have on Earth’s climate. Practically everyone uses Google, and many people are already familiar with the Google Earth interface. This makes learning easy as people do not have to get acquainted with a new system in order to operate the program. Using a product of a company as well-known as Google also helps to popularize the issue. Additionally, I think that using Google Earth is a great way to help people visualize climate change because it is so interactive. Overall, I think this is a fantastic resource!


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So, what exactly is the Higgs Boson?

Posted on March 19, 2013 by fathomingthestars

Now, I’m not going to pretend that I know as much about the now famous Higgs Boson as the scientists at CERN, but I do have a conceptual understanding of what it is and why it is important.  The Higgs Boson used to the only piece of the standard model of particle physics that we hadn’t discovered.  That all changed on July 4th, 2012, when the CERN scientists discovered a particle that might have been the Higgs Boson.  You may remember that the media, as it often does, incorrectly reported that the scientists had found the Higgs Boson.  It was not until very recently, March 14th in fact, when the CERN scientists were confident enough to announce the particle they had found was indeed the Higgs Boson.

With the history lesson over, I’ll dive into the more science-y bits.  The minutephysics video below does a good job explaining the Higgs Boson (and has a three part series on it), but I will flesh out the details below.

The Higgs Boson itself is not actually all that important.  What the Higgs Boson confirms, however, is what makes it’s discovering vital to particle physics.  The Higgs Boson is a remnant of the Higgs Field, proposed by Peter Higgs.  If you have read anything about the Higgs Boson, you might have seen that it gives particles mass.  That’s not quite true.  It is the Higgs Field that does the mass-giving.  Without the field, particle physicists cannot explain why particles have the mass they do.  Think about the Higgs Field like skiing down a mountain.  Particles with little mass, like the electron, interact very little with the field, like a skier skimming over the snow.  Massive particles, like protons and neutrons, interact much more strongly with the field, like someone walking through a foot of snow.

The mass-giving property of the Higgs Field is what is mentioned most by the media, but the Higgs Field plays another important role in the weak nuclear force.  The weak nuclear force is one of the four fundamental forces (the other three are the strong nuclear force, the electromagnetic force, and gravitational force), and is probably the hardest to understand.  The weak nuclear force allows particles to change into other particles.  This means one flavor of quark can change into another flavor of quark, which in turn can change a proton into a neutron, for example.  This decaying of one particle into another is extremely important, as you might remember, because it makes the Sun work and gives us radioactive dating (as well as a bunch of other stuff).  Here is a very good YouTube video explaining the weak force.

To summarize: the Higgs Boson proves the existence of the Higgs field, which helps us understand the weak nuclear force and how particles can have mass.


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Kepler’s Supernova

Posted on March 19, 2013 by juliettealper

Image

In 1604 Johannes Kepler discovered a supernova explosion. Today, scientists are working to discover what caused the explosion and they are using a Digitized Sky Survey to determine it. The picture above shows colors from an X-Ray Observatory that concludes the supernova has low, intermediate and high energy. Scientists believe this explosion was caused by a reaction between a white dwarf and a red giant star. The supernova data shows a disk shaped structure near its center, as well as iron asymmetrically balanced on one side of the center but not the other. All of this information is interesting, and helps scientists better understand how the Supernova Remnant came to be and what caused it’s explosion.

For more information: Click Here!


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Trous Noirs And trous noirs

Posted on March 19, 2013 by ibrahim2016

For an explanation of the title, see the link at the end.

If you are seriously, irreconcilably frustrated by your significant other (or lack thereof) and you never want to see your significant other (or yourself) ever again, please accept a sincere piece of advice from me: Do not- I repeat: DO NOT throw them(or yourself) in a black hole. That would be a bad idea.

"I wasn't gonna push her!"

“I wasn’t gonna push her!”

Now the sensible will decimate my sagely wisdom because of the sheer improbability of a black hole ever crossing two recently uncrossed star crossed lovers. But the curious(and the willing) will ask: Why?

Because the face of the victim will adorn the cosmos for the rest of your life. That kind of kills the point of throwing someone into a hole which never spits anything out. Why?

In my previous article I wrote about how a black hole is formed. Now I will write about why black holes are great advertisement spots and potential reminders of every regretful thing you did in your life. Einstein pointed out in his general theory of relativity that gravity distorts space and time. So for an observer at an arbitrary distance, a clock near a massive object will appear to run slow. The nearer the clock is to the object’s center, the stronger will be the gravitational field, and the slower it will run (for less massive objects the clock will have just to be nearer to the center). However, there is a problem with heavy objects: they are usually very large. Therefore a clock won’t be able to get closer than the radius of the object. So the effects of time dilation won’t be apparent.

Black holes, however, have a zero radius. So objects can get close enough to experience significant relativistic effects. I will be using the case of you, and your significant other (real or imaginary) who recently lost his/her position of significance (and their balance on the space ship, apparently; sshhhh!):

time_dilation_gravity

In this picture, the green line represents the time measured by the observer(you) away from the influence of the black hole. The red line represents the time measured by the, uh, test subject. According to you, your time proceeds normally (the green line is not warped). The red line, even though it appears distorted to you, appears straight to the subject; just like you only have to walk straight without a care for the earth’s curvature to go to your destination, even though you appear to be moving in an arc to an observer in space. The numbers on both lines represent the hours elapsed since the break-up. Notice that the length between the hour intervals is the same for both green and red.

Now imagine that you both have clocks. Assume that the subject’s clock sends out a signal every hour. Also assume, for the sake of simplicity, that the signal reaches you instantaneously. As the warping of space time increases with decreasing distance to the black hole, you will get consecutive signals at ever increasing intervals, until at one point the next signal will take infinite time to reach you. However according to the subject, time will seem to pass normally because according to the subject, the red timeline is perfectly straight (just like with you and the earth). As you can see from the picture, no matter how far into time you progress, you will still get signals from the clock. That is to say, the simple act of disappearing forever will take your significant other an unimaginable long amount of time; and they wont even notice that you are getting impatient. As I said: bad idea.

To understand how the timelines work click here.

An explanation of the title here.


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Relativistic Doodles

Posted on March 19, 2013 by ibrahim2016

This post explains how my illustration of general relativistic time dilation works. This is the parent post.

Here is an image of a simple classical timeline:

timeline_1

There are 2 observers: green and red. They have their own watches. The red observer shoots an arrow towards the green observer. The position of the arrow vs. the time recorded by the two observers looks like the picture above. If we take a trace of the trajectory of the arrow, we get:

timeline_2

If we were to take the trace of a 2 signals 1 second apart that travel at constant speed, and 2 signals 1 second apart and traveling instantaneously, we would get:

timeline_3

You will notice that the components of all 4 traces (like the ones drawn in grey) are parallel and perpendicular to the space-time axes. This is always the case. So even when I distort the edge of the red timeline a bit, I get:

timeline_4

So if I am standing with the red observer, and I see him sending out signals, I will not notice a difference even when the red timeline distorts, because to me, the components of the signals are still parallel and perpendicular to my space and time. In the same way, when an observer is falling into a gravity well (like that of a black hole) and sends out signals, the observer does not notice the relativistic effects of gravity on the signal. However, the observer who is standing far away from such distortions notices an altered signal. So even though the signal at t=8 was instantaneous according to the red observer, it reached the green observer at t=9.

If you understood this, then you will know what is wrong with this set of traces of signals that a red observer sends as she falls into a black hole:

time_dilation_gravity_WRONG


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Mars: Trend in Water Presence

Posted on March 19, 2013 by indianwm

Last week, the Mars rover named Curiosity, found evidence for water-bearing minerals in rocks.

The rover Curiosity was launched in 2011 from Cape Canaveral and landed on Mars in August, 2012. This rover is equipped with many devices that have multiple uses for observing and testing the terrain and environment on Mars. Among these is a Mast Camera that can detect minerals and hydration. Curiosity is also equipped with a camera capable of infrared imaging which works by sending neutrons into the ground to detect hydrogen. Through using these tools, Curiosity has been able to make many discoveries on Mars, the most recent is that of water-bearing minerals in rocks. The science team that uses the rover discovered that the powder that was drilled from a rock on Mars suggests that there were environmental conditions that would be conducive to microbial life. When conditions for life are found on a distant planet, it is very exciting for the astronomy community. If life could have been sustained on Mars, then there is that much more of a chance that there is life currently out there on some similar planet in another solar system or galaxy.

Mars Rover Curiosity

 


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Alien Life: More Probable Than We Think

Posted on March 19, 2013 by Will K

Found in a deep mine on Earth, this microbe could survive on Mars. This discovery provides move evidence for the existence of alien life.

 

The possibility of alien life throughout the universe has consistently captured the human imagination. From science fiction novels to movies to television documentaries the idea alien life forms appears again and again. While some people may be skeptical, there is some truth to the stories and speculations.

First of all, the possibility of alien life can be seen through the lens of probability. There are so many stars in the galaxy, let alone the universe, that there must be life somewhere. According to an interview with NBC; Seth Shostak, a senior astronomer at the SETI Institute, “estimates there are 1 trillion planets in the Milky Way alone.” This means that it is very probably that at least one planet out there developed in much the same way as Earth did.

Alien speculators are also encouraged by the possibility of life that we see in our own solar system. Water is not all that uncommon on places like Europa and other Jovian moons. Researchers also believe that there may be liquid water under the surface of Mars in addition to the frozen water at the ice caps. The possibilities of liquid water so close to home coupled with the enormous probability of similar planets outside the solar system makes the possibility of life seem ever more reasonable.

Finally, biologists on Earth have discovered life in the most extreme places imaginable. From beneath the Antarctic ice to the driest desert, life can adapt to extreme conditions here on Earth. These extreme conditions are even similar to places beyond the Earth, like Mars or the Jovian moons. As researchers discover more and more life here on Earth the possibilities of life elsewhere becomes more realistic.

As we expand our view of the universe as well as our own planet we are discovering that alien life is more probably than it seems at first. It is only a matter of time before we find alien life or it finds us.


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Alien Life: More Probable Than We Think

Posted on March 19, 2013 by Will K

Found in a deep mine on Earth, this microbe could survive on Mars. This discovery provides move evidence for the existence of alien life.

 

The possibility of alien life throughout the universe has consistently captured the human imagination. From science fiction novels to movies to television documentaries the idea alien life forms appears again and again. While some people may be skeptical, there is some truth to the stories and speculations.

First of all, the possibility of alien life can be seen through the lens of probability. There are so many stars in the galaxy, let alone the universe, that there must be life somewhere. According to an interview with NBC; Seth Shostak, a senior astronomer at the SETI Institute, “estimates there are 1 trillion planets in the Milky Way alone.” This means that it is very probably that at least one planet out there developed in much the same way as Earth did.

Alien speculators are also encouraged by the possibility of life that we see in our own solar system. Water is not all that uncommon on places like Europa and other Jovian moons. Researchers also believe that there may be liquid water under the surface of Mars in addition to the frozen water at the ice caps. The possibilities of liquid water so close to home coupled with the enormous probability of similar planets outside the solar system makes the possibility of life seem ever more reasonable.

Finally, biologists on Earth have discovered life in the most extreme places imaginable. From beneath the Antarctic ice to the driest desert, life can adapt to extreme conditions here on Earth. These extreme conditions are even similar to places beyond the Earth, like Mars or the Jovian moons. As researchers discover more and more life here on Earth the possibilities of life elsewhere becomes more realistic.

As we expand our view of the universe as well as our own planet we are discovering that alien life is more probably than it seems at first. It is only a matter of time before we find alien life or it finds us.


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