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It’s strange to imagine, but physicists cannot accurately describe nearly three quarters of the matter and energy in the universe. Because as it turns out, nearly 73% of the universe is composed of a mysterious substance called dark energy. In physical terms, no one knows exactly what dark energy is. Instead, dark energy is a theoretical construct that permeates all of the space in the universe and can provide an explanation as to why the expansion rate of the universe is increasing. Simply put, Dark Energy is a force that is intrinsically found in space and is causing the expansion rate of the universe to increase.

There are different opinions as to how and when Dark Energy was discovered. Although physical observations have only recently confirmed the existence of dark energy, some say that Einstein discovered Dark Energy way back when he was formulating his General Theory of Relativity. While making the General Theory of Relativity, Einstein originally added the “cosmological constant” into his equations in order create a static universe. In this original formulation of General Relativity, the cosmological constant acted as a mysterious force that caused the universe to expand; this was necessary in order for General Relativity to predict a static universe, which Einstein wanted. However, Einstein then removed this cosmological constant when observations by Hubble indicated that the Universe was expanding. But since the cosmological constant causes the Universe to expand and would permeate all of space, it is essentially dark energy.

However, others say that dark energy was really discovered in 1998, as this was the first time a physical phenomenon that required the existence of dark energy to be explained was observed. Scientists from Berkeley and scientists from Australian National University observed two supernovas that were farther apart than models would predict in a universe that lacked dark energy. Consequently, others say that these scientists discovered dark energy.

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If an alien civilization tried to reach out to us, how would they do it? Radio waves are the obvious answer; they travel far and only require a small power input. But what type of radio signal would aliens send?

In the early seventies, physicists Phillip Morrison and Giuseppe Cocconi predicted that an alien civilization would transmit a radio signal at 1420 MHz and in a narrow band frequency. Why? An alien signal would have to be something more fundamental and universal than language, something that any intelligent civilization would understand. So why not use a number associated with the most common element in the universe, hydrogen? Hydrogen emits radiation at 1420Mhz. Furthermore, Morrison and Cocconi predicted that an extraterrestrial civilization would send the signal at a narrow band frequency, as narrow band frequency signals require less energy and are created by no natural phenomena.

On August 15, 1977, an exact match for this signal predicted by Morrison and Cocconi arrived on a detector in Delaware, Ohio. Astronomer Jerry Ehman, who first discovered the signal in the data a little while later, christened it the, “Wow!” signal. It has never been explained since.

Picture of Global Warming

Everyone worries about global warming these days. As a direct result of humans pumping trillions of tons of carbon dioxide into the atmosphere, global temperatures are predicted to steadily climb, leading to the melting of the polar ice caps by around 2100 (according to the most dire predictions) and a vast rise in sea level that would put modern coastlines under water. The only chance humanity has of halting the progress of global warming is to cap our emission of carbon dioxide, and even then a significant amount of warming will likely still occur (as a result of the CO2 already in the atmosphere). Or is there another option?

There is… geoengineering. Earth scientists have come up with a multitude of ways that people could cool the climate in order to mitigate or prevent the effects of greenhouse gas-induced global warming. In this blog, I’ll focus on the most likely and most cost effective method: sulfur dioxide emission

How It Works:

·         Using commercial planes, military fighter jets, or even giant balloons,  vast quantities of sulfur dioxide would be transported into the stratosphere daily

·         Once in the atmosphere, the SO2 would oxidize to form sulphate (SO4) aerosols

·         Sulphate aerosols are reflexive, so they will reflect some sunlight from the earth and thus cool the planet

·         This concept has already been demonstrated in principle with the Mt. Pinatubo volcanic eruption in 1991. This eruption unleashed a huge quantity of sulfur dioxide into the atmosphere, and global temperatures fell by half a degree Centigrade a year later.

Potential Drawbacks:

·         Although the sulfur dioxide approach would help with global warming, it would do nothing to combat the ocean acidification that carbon dioxide emission is causing

·         The world would need to come to an international consensus before this plan could be put into place

·         Since current climate models aren’t very accurate, there is a very real possibility that humans could overcompensate with the sulfur dioxide and cause too much cooling

·         The view of the stars with underground telescopes would be obscured because of all of the aerosols in the air… KHS Astronomy Club… Bye bye…

·         Solar power would be less efficient

·         Potential drought; the year after the Pinatubo eruption had the lowest rainfall over land ever recorded

Should we geoengineer? The potential problems are real and dangerous. Still, global warming is just as real and dangerous, and geoengineering may be the only way to stop drastic climate change. As time moves on, people will have to weigh the costs and benefits of geoengineering against the consequences of global warming. For instance, which is worse… The drought that would likely be created from sulfur dioxide geoengineering, or the worse hurricanes and rising sea levels that would result from global warming? More importantly, who decides? Thoughts?

Sources:

http://arstechnica.com/science/news/2009/10/weighing-the-pros-and-cons-of-stratospheric-geoengineering.ars

http://www.climateark.org/shared/reader/welcome.aspx?linkid=140354

Superfreakenomics  by Stephen J Dubner and Steven Levitt

Black Hole

“Black holes have no hair.” So said physicist John Wheeler. This statement seems obvious: a black hole is a region of space time that contains so much matter that its gravitational field is intense enough that not even light can escape from it. So why would a black hole have hair? But what Wheeler really means is much more interesting. Black holes may really just be giant elementary particles (elementary particles: proton, neutron, electron, etc.).

To begin with, what makes one type of elementary particle, say a proton, different from another, say an electron? There are really only three characteristics that differentiate them. The first is mass: the proton is bigger. The second is charge: the proton has a positive charge, while the electron has a negative charge. The third is spin: some electrons spin clockwise, others spin counter clockwise.

Now for a similar question: what makes one black hole different from another? It turns out that, like elementary particles, black holes have only three distinguishing characteristics: mass, charge, and spin. These are the exact same distinguishing features of elementary particles! (This is what Wheeler means when he says black holes have no hair: they are relatively similar to each other, and lack complicated hair dos to differentiate themselves.)

So, if black holes have the same distinguishing characteristics as elementary particles, are they the same thing. At first thought one may assume not; black holes are massive and elementary particles tiny. However, physicist believe that microscopic black holes the size of elementary particles do exist. And the other traits: charge and spin, can also be exact. So if one had a microscopic black hole that matched the exact size, charge, and spin of a specific elementary particle, might the black hole actually be that elementary particle? Who knows? For a more in depth look at this topic, check out: The Elegant Universe by Brian Greene.

Brad Rybinski

The Iconoclast: Absolute Hot

Most people reading this are familiar with the concept of absolute zero: Zero degrees Kelvin        ( -273 degrees Celsius) is the coldest temperature possible, and at this temperature matter is not moving at all. In reality, absolute zero can never be actually achieved, and even if it could the matter would still be moving slightly. So much for high school chemistry. But I digress, as absolute zero is not the point of this article…

The point of this article is that there may be an “opposite” to absolute zero. Appropriately, it is called “absolute hot”, and represents the highest attainable temperature a hunk of matter can reach. Absolute hot is estimated to be reached at 1.41678571 × 10³²  degrees Kelvin. This temperature is known as the Planck temperature, and the laws of physics are said to breakdown once one reaches this point. Specifically, the four fundamental forces of nature (gravity, electromagnetism, the weak force, and the strong force) are said to unify into a single force, and weird things happen to space and time.

For more information and a more research perspective on this, see: http://www.pbs.org/wgbh/nova/zero/hot.html

Brad Rybinski

Aliens… The word conjures up images of exotic space craft, advanced beings, and menacing probes.

But what are the odds that an alien civilization actually exists? Moreover, what are the odds that the high tech, communicating alien civilization we all imagine actually exists? Believe it or not, American astronomer  Francis Drake developed an equation(the Drake equation) that allows one to predict the number of advanced alien civilizations in our galaxy. The equation is as follows:

N = N* fp ne fl fi fc fL

N* represents the number of stars in the Milky Way Galaxy (most scientists agree that this number is about 100 billion)

fp is the fraction of stars that have planets around them (Experts agree on a range of 20% to 50%)

ne is the number of planets per star that are capable of sustaining life. Though most scientists would estimate this number is between 1 and 5, they have little evidence to base such an estimation on, and out of the roughly 250 planets astronomers have discovered, they suspect they have found only 1 (other than earth) that may be capable of sustaining life.

fl is the fraction of planets in ne where life evolves. Scientists have no way of knowing this, and estimates range from 100% to just over 0.

fi is the fraction of fl where intelligent life evolves. Scientists have no way of knowing this either, and estimates range from 100% to just over 0.

fc is the fraction of fi that communicate. Yet again, scientists have no way of knowing this.

fL is fraction of the planet’s life during which the communicating civilizations live. As you may have guessed by now, scientists have no way of knowing this one either.

Obviously, the Drake equation’s ability to accurately predict the number of alien civilizations out there is limited by the fact that no one knows the precise values of any of its variables. However, the equation works in principle, and it is a fun thought experiment. I tried the equation using my own estimates for each of the variables, and according to my estimates, there should be 33 high tech, communicating alien civilizations in our galaxy. If you would like to try the Drake Equation for yourself, and find out how many alien civilizations you think are in our galaxy, just go to http://www.activemind.com/Mysterious/Topics/SETI/drake_equation.html .

Brad Rybinski