Contacting Aliens

The question of whether intelligent extraterrestrial life exists or not has intrigued millions of people and has led to movies like E.T., Independence Day, and War of the Worlds. Movies like these show how innately curious we are about extraterrestrial beings. Since 1960, our curiosity has led us to start systematically scanning the sky for evidence of aliens, and even to try to contact them.

The first project in the Search for Extraterrestrial Intelligence (SETI) was named "Project Ozma" and was led by Frank Drake, who used a radio telescope in West Virginia to examine the stars Tau Ceti and Epsilon Eridani near the 1.420 Gigahertz frequency. That frequency is dubbed the "water hole" in the radio spectrum because of its proximity to the spectral lines of hydrogen and the hydroxyl radical, which combined make water, a necessity of life, and also because it is where extraterrestrials might gather to communicate, much like animals at the water hole. Since then SETI projects have mainly focused on using radio telescopes to search for signals that might give us any clues on whether extraterrestrial life exists. One of the well-known SETI projects, Sentinel, was led by Paul Horowitz, who built a spectrum analyzer to search for SETI transmissions that had 131,000 narrow band channels. Even then, the search came up empty. 

Not only have astronomers searched for extraterrestrial intelligence, but they have also begun transmitting messages as well, hoping that extraterrestrial life will hear them and respond. The first message was transmitted by the Arecibo Observatory Radio Telescope in Puerto Rico, the world's largest single-aperture telescope, in 1974. The first message described our solar system, the compounds important for life, the structure of the DNA molecule, and the form of a human being.

In the image below we see a color version of the message transmitted, the message consists of seven parts that encode the following:

1. The numbers one to ten.

2. The atomic numbers of the elements hydrogen, carbon, nitrogen, oxygen, and phosphorus, which make up DNA.
3. The formulas for the sugars and bases in the nucleotides of DNA.
4. The number of nucleotides in DNA, and a graphic of the double helix structure of DNA.

5. A graphic figure of a human and the human population of Earth.

6. A graphic of the Solar System indicating which of the planets the message is coming from.

7. A graphic of the Arecibo radio telescope and the dimension of the transmitting antenna dish.
The message was transmitted in the direction of the globular cluster M13, about 21,000 light years away.

The idea of communicating with aliens has caused a stir. The likes of Stephen Hawking and science fiction author David Brine agree that transmitting messages attract the bad kind of aliens depicted in movies ranging from War of the Worlds to Independence Day. Hawking imagines that our first contact with extraterrestrials could be like the Native Americans' first contact with Europeans, "which didn't turn out very well for the Native Americans." Others disagree, saying they will help us advance as a civilization. The deed is done, but it will be still a long time until we hear a response and find out whether sending messages was our greatest feat or our worst error.

See:
http://www.nbcnews.com/science/space/be-or-not-be-signaling-aliens-question-seti-n305546
http://www.seti.org/seti-institute/project/details/arecibo-message
http://en.wikipedia.org/wiki/Arecibo_message
http://en.wikipedia.org/wiki/Search_for_extraterrestrial_intelligence

- José Uribe

The End of the Universe

In 1929, Edwin Hubble made an important discovery about the universe: it is expanding. Galaxies are, in general, moving away from each other, with space itself expanding between them. So the question arises: Will the expansion continue forever? And if so, how fast will it go? Scientist have determined that the universe consists primarily of three substances: “dark matter,” “normal matter,” and an unknown energy, “dark energy.” The first substance, dark matter, contributes to the force of gravity that would cause the universe to collapse in on itself. The second one, normal matter, consists of atoms that make up human beings, stars, planets, and other visible objects. The third substance,

dark energy, is proposed to be a repulsive force that would cause the universe to expand. The expansion rate is related to the sum of the densities of each substance. According to the data of the WMAP satellite, 72% of the universe is composed of dark energy, 24% of the universe is dark matter, and 4% is normal matter. The proportions of dark matter, normal matter, and dark energy are such that the universe’s expansion is currently accelerating; however, we do not know for sure what the expansion rate will be in the future.

With the discovery of the expanding universe, astronomers realized that the universe is a dynamic, evolving environment. While the universe has been expanding ever since the Big Bang, a natural question is, will that expansion continue forever? In other words, what will be the final fate of the universe?

There have been four proposed ways in which the universe might comes to an end. These are “The Big Rip,” “The Big Freeze,” “The Big Crunch” and “The Big Bounce.” Today, I will talk about the Big Freeze. In this scenario, the universe expands forever. Since the expansion rate of the universe at a particular distance is currently accelerating and will eventually exceed the speed of light, after billion or maybe trillion years, light emitted from currently observed clusters of galaxies will no longer reach us. Thus, neighboring clusters will disappear, and we will end up as an isolated community. Stars will have used up their nuclear fuel and become dark, and will perhaps become white dwarfs, neutron stars or black holes. After 10²³ years, the temperature all across the universe will reach to nearly absolute Zero. Eventually, it will be cold enough for black holes to shrink away and evaporate. At that point, even consciousness or thought cannot exist. The entire universe will become dark, cold, and lifeless.

What is the ultimate fate of our universe? A Big Crunch? A Big Freeze? A Big Rip? or a Big Bounce? Current observations have led cosmologists to favor “The Big Freeze.” However, the other three theories still cannot be totally ignored until the dark energy is fully understood.

See:
https://cosmology.carnegiescience.edu/timeline/1929
http://www.aip.org/history/cosmology/ideas/expanding.htm
http://wmap.gsfc.nasa.gov/media/080998/
http://www.universetoday.com/36917/big-freeze/
https://www.youtube.com/watch?v=NLSkZ4Z2ttk

- Cora Wu

Fading Away into Oblivion: The Many Fates of our Universe

Despite how preciously we may view life and the legacy that we leave, everything we value will becomes obsolete as the universe ages through many millennia. As time goes on, and our society crumbles, our universe will undergo a fate predetermined by physics. There are three main theories that underlie the fate of the universe: the Big Freeze, the Big Rip, and the Big Crunch. All three deal with the expansion of the universe, and are dependent on how fast it actually expands.

Astrophysicists Jamal Islam and Freeman Dyson first theorized the Big Freeze in the 1970s and divided the universe into five eras from the birth of the universe, the primordial era, to the dark era, where everything has decayed. This theory deals with the continual expansion of the universe, which will lead it to gradually cooling until it approaches a temperature of absolute zero As time passes, stars slowly start to fade away while the distance between galaxies continues to grow due to the expansion. After the stars fade away due to lack of fuel, only black holes will remain until they disappear as well due to Hawking radiation. This continues until no further mechanical work is possible, which leads to the final death of the universe.

Another theory, the Big Rip, first published in 2003, theorizes that as the universe expands until all matter is torn apart. This largely stems from the effects of “dark energy” which pulls objects apart. There is evidence dark energy may get stronger as the universe expands. If dark energy gets to the point where it is strong enough to overcome gravity and nuclear forces, it will end up pulling these objects apart. This will lead to clusters of galaxies disbanding, and even all life on Earth being torn apart as the dark energy will overcome their forces of attraction, hence the name, the Big Rip.

The Big Crunch is different from the first two theories in that it deals with the eventual reversal of the universe where it will recollapse back into a black hole singularity. This deals the fact that the expansion speed of the universe may be slow enough that gravity will eventually stop the expansion and cause the universe to contract and implode upon itself. However, this will only occur if the density of the universe is sufficiently large such that the strength of gravity overcomes the expansion.

All of these theories are potentially valid, and will occur in the distant future, billions of years away. It all depends on how dense the universe is and the physical makeup of dark energy, both of which are still uncertain. There are many mysteries still out there dealing with the physics of the universe, and we will have more than enough time to address them, but maybe not solve them.

See:
http://www.universetoday.com/107316/what-is-the-big-rip/
http://hubblesite.org/hubble_discoveries/dark_energy/de-fate_of_the_universe.php
http://www.physicsoftheuniverse.com/topics_bigbang_bigcrunch.html

- Charles Wang

Universe or Multiverse?

With current technologies, astronomers are able to see objects as they exist up to 13.7 billion years ago. There is no reason to think the universe just stops there. Beyond what we can see may lie infinitely many realms much like or different from our own. Each may have a different initial distribution of matter, as well as distinct laws of physics. Together, the infinite regions create what astronomers refer to as the "multiverse."

Astronomers believe that our universe experienced a sudden burst of rapid expansion in mere fractions of a second after the Big Bang, causing the universe to grow from "an infinitesimally small speck to one spanning a quarter of a billion light-years in mere fractions of a second" (Shmahalo). While individual regions become "bubble universes" and stop inflating, the exponential expansion, once started, continues forever. As it continues to expand, some parts quicker than others, new "bubble universes" are formed. Inflation lies at the foundation for the multiverse theory.

Since 30 years ago, observations of the cosmic microwave background, the light emitted by the cooling universe 380,000 years after the Big Bang, have offered support for inflation. The size of the blotches in the cosmic microwave background follows a distribution that is consistent with inflation models. Alan Guth, an MIT theoretical physicist says "It's not impossible [to build models that do not lead to a multiverse], so I think there's still certainly research that needs to be done. But most models of inflation do lead to a multiverse, and evidence for inflation will be pushing us in the direction of taking the idea of a multiverse seriously." With possible evidence of inflation, models for multiverse come naturally. On March 17th of last year, John Kovac of the Harvard-Smithsonian Center for Astrophysics and his BICEP2 "a distinct curl in the polarization pattern of the CMB," or Cosmic Microwave Background (Kramer). This "distinct curl" can be interpreted as being caused by inflated gravitational waves and thus would directly support both the theories of inflation and the multiverse. However, analysis of data from the Keck Array telescope at the South Pole and maps of dust emission from the European Space Agency's Planck collaboration has shown that the signal claimed to evidence of inflation is in fact caused by dust within the Milky Way. The dust finding does not necessarily refute inflation nor does it support the theory.

Thus, although there has been new findings that seem to support the multiverse theory, there is no direct evidence to prove it. All lines of "evidence" are currently indirect or ambiguous because they too are based on theories for the most part. As humans in our bubble universe, we cannot see what is happening outside. At least with current technology, we cannot say for certain whether a multiverse is possible. 

See:
http://www.space.com/21421-universe-multiverse-inflation-theory.html

http://www.space.com/25100-multiverse-cosmic-inflation-gravitational-waves.html
http://www.wired.com/2014/11/multiverse-big-bang/
http://physicsworld.com/cws/article/news/2015/feb/03/galactic-dust-sounds-death-knell-for-bicep2-gravitational-wave-claim

- Alice Zhang

What is a supernova and what is the possibility of one destroying Earth?

Supernovae are some of the most luminous objects in our night sky. A supernova occurs when a massive star collapses on itself after it runs out of fuel for its fusion process. Because iron cannot be fused with any element to create heavier atoms, the fusion process stops after iron is formed in the star’s core. Once fusion stops, there is no longer radiation pressure pushing outwards, so the star collapses upon itself with such force that a shockwave pushes through the surface and rips the star apart, creating one of the brightest explosions in space. Supernovae are very luminous but also very rare. Eight times the mass of the Sun is the minimum threshold for a supernova to occur; stars this massive are comparatively rare. Supernovae occur in the Milky Way Galaxy about once or twice per century.

Astronomers predict that the star Eta Carinae will soon undergo a supernova explosion. Although it’s over 7,500 light-years away from Earth, this supermassive star outshined Sirius, the brightest star in the night sky, from 1838 until 1858. However, because it is so far away from Earth, most of the harmful radiation that will be produced when the supernova occurs will disperse in the vacuum of space, with very little of it reaching our solar system. The closest supernova to have occurred near Earth since 1604 was 1987A, but it was still approximately 160,000 light-years away. Scientists expect Earth to receive a substantial burst of radiation from a supernova every 20 million years, enough to affect the atmosphere and the ozone layer. If the supernova occurs close enough to Earth, then life as we know it could be impacted dramatically.

How close does the supernova have to be to Earth to sufficiently impact life? At one hundred light-years and farther, a supernova poses no threat to Earth. Other than observing a bright light in our sky, we would experience no change on Earth. However, at fifty light-years away, a supernova will rip the ozone layer from our planet and destroy our magnetic field. Without a magnetic field, Earth would be bombarded by solar and cosmic radiation, causing a mass extinction of all complex life on the surface of Earth. What if a star one light-year away underwent a supernova? The closest star to us (other than the sun) is the red dwarf Proxima Centauri, which is just over four light years away. Although that star would never undergo a supernova, if in theory a star did so just one light year away from Earth, then not only our planet, but our entire solar system would be obliterated by the supernova’s shockwave.

Given current scientific estimates and predictions, the death of Earth by supernova is extremely unlikely if not impossible in the near future. So you can probably safely cross nearby supernovae off the list of possible threats to our existence on Earth, while being thankful that the ones that will occur in your lifetime will almost all be in galaxies far far away...

See:
http://www.space.com/4814-risk-earth-supernova-explosions.html
http://www.space.com/4462-stellar-explosion-outshines-sun-100-billion-times.html
http://earthsky.org/space/will-a-nearby-supernova-harm-life-on-earth-in-2012-nah
http://www.howitworksdaily.com/could-a-supernova-destroy-earth/
http://www.space.com/6638-supernova.html
http://phys.org/news/2014-05-gauge-hypothetical-disaster-supernova-earth.html

- Siqi Yang

What Will Happen When the Earth Stops Spinning?

We were taught in primary school that our Earth spins, and we accept it as a fact, but could you every imagine a world where the Earth stops spinning? In the National Geography program Aftermath, scientists explored an interesting topic: What will happen if Earth slows down and eventually stops spinning in five years? I would like to share with you this novel idea and its unimaginable consequences.

Our solar system was born 4.5 billion years ago from a spinning cloud of gas and dust. Because angular momentum is conserved, when the planets formed from this spinning cloud, they themselves spun, and they continue to spin to this day. The Earth is turning more than sixteen hundred kilometers a hour but is gradually slowing down, at a rate of about two seconds every 100,000 years. What if this rate were to greatly increase?

At first with only a minor decrease in the speed of spinning, disasters begin to occur. The Global Positioning System, or GPS, relies on satellites and satellites are in geosynchronous orbit: they are at a height above the Earth such that they orbit the Earth once per day, making them stay on top of a single point. These satellites don’t expect the Earth to slow and eventually start orbiting faster than the Earth spins, leading to a chaos in the entire GPS system. Computers lead airplanes far from their original routes, and hundreds and thousands of people are at risk when pilots suddenly find out that their navigation system is not working. What immediately comes afterwards is the failure of the travel industries bringing an unimaginable global economic crisis.

As the Earth’s spin slows more, worse catastrophes hit our planet. Our Earth is fatter in the middle than at the poles. Spinning causes both land and water to bulge outwards at the equator, due to centripetal force. But as that force weakens, seawater starts moving away from the bulging equator towards the poles, and a billion cubic kilometers of water is on the move, flooding cities on the way, making them uninhabitable.

As the sea level changes the very air we breath is changing too. Our atmosphere is evenly spread across the planet. And it rotates along with the Earth.As the earth slows down, the atmosphere follows the oceans toward the pole. Among the first hit cities in the tropics are Rio de Janeiro and Singapore, where it gets harder to breathe. People living at higher altitudes are also starting to feel the struggle. Humans can begin to feel altitude sickness at less than 2,500 meters and just over 5000 meters is the outer limit of survival.

In many areas of the world thin air and flooding are not yet taking lives, and people are coping. But as the Earth slows more, suddenly all over the world their is a more deadly problem—earthquakes where there have never been earthquakes before. The Earth has 3 layers and they all rotate together. But as our spin decreases each layer slows at a different speed, unleashing massive fiction. The Earth literally tearing itself apart from inside.

Water is flooding from the south and air is thinning from the north and earth is tearing from below, soon there will be no place suitable for people to live. Eventually there would be only one climate, no more wind and no more pressure, everything being controlled by the sun. And with one last hit, being that with longer nights the temperature drops to lower than minus 50 degrees, the only thing people could do is wait for their doom.

- Zhichuan Duan

Revolving Around the Arts and the Sciences

Warning of possible spoilers

It’s all too common. We read books, watch movies, visit websites that claim to have the most accurate facts. But in reality…how much of the facts are actually legit? How can we be sure that the facts are correct without having to dig deep into a textbook or encyclopedia? We often wonder because many forms of media want to include technical facts on topics such as science or history. Today, I am going to check out the validity behind the astronomy in the critically acclaimed movie Interstellar.

Wormhole

Just to give some background information: the basic storyline of the movie is that Earth has become uninhabitable due to crop failure. A team of astronauts is sent up to space to travel to a separate galaxy via a wormhole. On the other side of that wormhole are multiple planets that orbit around a gigantic black hole. The astronauts are tasked to investigate three of the planets (named Miller, Edmonds, and Mann), which from previous space expeditions are still transmitting pings back to Earth.

Black hole

First let’s go with the facts that seem reasonably correct. Many sources explain that time dilation is represented accurately throughout the movie. With the help of general relativity, the closer you are to a really large object, the slower time passes. So during the movie when they are on a planet that is super close to the black hole, it makes sense that a couple hours on that planet can mean decades on Earth. When they learn the planet is inhospitable, they realize that the beacon sending the pings was in reality only active for a couple minutes on the planet (translating to decades of pings back on Earth). As they move farther from the black hole to explore the other two planets, rushing to save time on each planet is less relevant because the effects of time dilation are diminished.

Two other objects that are pretty well represented in the movie is the wormhole they travel through to get to the new galaxy and the gigantic black hole. When making the wormhole Kip Thorne and a team of 30 physicists researched and wrote new equations that led to another team writing new software to render a physical model. What popped out was an orb-like object. As for the black hole, the gravitational lensing around it (matter in between an object and observer can distort light) and the accretion disk (a disk of matter and light that is sucked in by the black hole) are both as accurate as the laws of physics can make it.

But while the models were visually accurate, the way they interacted with other objects might be a bit iffy. One concept a lot of astronomers and physicists are discussing is the idea of spaghettification. When Cooper falls into the large black hole, his feet technically feel a larger gravitational pull than his head. Since this black hole has an insane gravitational pull, as Cooper enters the black hole, he should be violently stretched out. But he isn’t. In addition, the he wasn’t attacked by intense x-rays that accretion disks are known to emit.

Another issue is how the scientific process is portrayed in the movie. Back on Earth, Professor Brand tries to solve a conceptually difficult problem by trying to harness the power of gravity to send a huge space station to space. Throughout the movie he is shown trying to solve this problem with only one other scientist. There is just a two-man team trying to potentially save all of humankind. Where are all the other scientists, astronomers, and physicists? In another scene, the space crew is deciding which planets they should go to first. Shouldn’t all of this be initially planned? Where are the contingency plans? Where are the contingency plans to the contingency plans? It seemed everything was thought of on the spot, something space travel is not about.

Interstellar, in my opinion was great. The visuals, accompanied with a fitting soundtrack, made it an entertaining movie. After doing some research, it seemed like a lot of science was thought out thoroughly and painstakingly researched. But, unfortunately, there are details in the science that the most die-hard science fans will find inaccurate. 

Sources:
http://en.wikipedia.org/wiki/Interstellar_%28film%29
http://www.wired.com/2014/10/astrophysics-interstellar-black-hole/
http://www.worldsciencefestival.com/2014/11/cinema-peer-review-astrophysicist-katie-mack-reviews-interstellar/

- Eric Lee

Why We Orbit the Sun

The formation of the universe and relevant theories such as the Big Bang are commonly discussed topics among astronomers, physicists, and even ordinary people. However, the formation of our immediate solar system is often not given much attention. The most widely accepted theory about how our solar system (the Sun and the eight orbiting planets) came to be is called the “solar nebula theory.” This theory quickly gained popularity among astronomers as well as the public. It is important to note that this theory is applicable to the rest of the universe, not just our solar system.

We begin with a massive, relatively cold cloud of gas and dust called a nebula. Gravitational force causes the dust to collapse inward. It is believed that the nebula is initially spinning slowly. As the nebula collapses, the system spins faster by conservation of angular momentum. Clumps of matter run into each other to form larger clumps called planetesimals and eventually become full-size planets. Over time, the random velocities and directions of the objects average out to form one rotating disk, with a protosun in the center. As the nebula continues to condense, the energy it contains from the gas pressure is released as heat, which explains the intense temperature of our sun. The objects in the disk continue to run into each other, eventually forming our “clean” solar system that we know today.

There is good evidence to believe that the solar nebula theory is correct. First of all, this theory accounts for the fact that all of our planets lie on one plane, and they all spin and revolve in the same direction. It also successfully explains why there is a sun in the center and how it became a shining star. At the center of the nebula, the temperature and density was hot enough to begin nuclear fusion.

Unfortunately, the solar nebula theory fails to explain certain observations. If, indeed, the sun formed by the collapse of clouds, we would expect the sun to spin faster and the planets to spin slower than they do. We would expect this because the sun contains approximately 99.9% of the solar system’s mass, but only accounts for 1% of its angular momentum. One proposed explanation is that solar wind leaving the Sun carried much of the initial angular momentum away with it. Even today, we observe the Sun’s rotational speed slowing down. Nevertheless, the nebular hypothesis continues to be the dominant theory today. We have recently taken a great number of photos of faraway nebulae where new stars are constantly being formed, providing visual support of the nebular hypothesis.

- Sarah Shy

Water on Mars

Ever since Giacomo Miraldi observed white spots near the poles of Mars in 1704, scientists have been wondering whether Mars has water. Sir William Herschel, the British Astronomer Royal, assumed that the dark areas he observed through his telescope were oceans, but in the 20th century, the idea of currently having liquid water on the surface of Mars was rejected. In 1964, when scientists were able to send Mariner 4 into the universe, they received clear images of Mars. These images show that there were only ice caps at the north and south poles of the planet, with no evidence of water existing on the surface today.

There are two principal reasons why water is not found today on the surface of Mars. First of all, Mars is much farther away from Sun than the Earth is. According to NASA, the longer distance makes the average Martian temperature 130 degrees Fahrenheit less than that of Earth. In addition, the Earth’s atmospheric pressure is about 100 times that of Mars. Under such low pressure, water condenses into ice easily.

Water partially filling Gale Crater.

However, there is speculation that surface water may have existed at one time. In 2011, mineral-mapping data from more than 350 sites showed evidence of clay that would have formed billions of years ago. Since rocks have to interact with water to form clay, the appearance of clay on Mars suggests that water had existed, even though maybe only for a short period of time. More evidence for past water came in 2014, when NASA’s Curiosity rover found evidence of an ancient lake in Gale Crater. Scientists believe that a river once flowed into the crater, bringing bits of sediment and depositing them in the lake.

Mount Sharp

These sediments slowly formed into rocks. The river brought in enough water to help form Mount Sharp, an 18,000-foot-high mound of sediment at the center of Gale Crater. The discovery of clay suggests that Mars may have been once warm and wet, and thus may have been able to support life. Some scientists have even made the bolder claim that Mars once has a thicker atmosphere that raised the temperature above water’s freezing point, but this has yet to be proved. 

Two future NASA missions will look for further evidence of past water and life on Mars. In January 2016, NASA is going to launch the ExoMars Orbiter. It is designed to figure out if life ever existed on Mars. In 2020, NASA will launch a robotic science rover to further search for possible signs of past microbial life on Mars by studying the different kinds of soils and rocks. It will also address the challenges that human will face during future expeditions on Mars. Other tasks of this rover include testing the ability to extract oxygen from Mars’ atmosphere and monitoring its weather and dust storms.

Mars resembles the Earth in many ways, from the length of its day to the tilt of its axis, and from its average speed orbiting the Sun to the number of its moons. By studying Mars, scientists may find clues as to how the Earth will look millions or billions of years from now.

See:
http://mars.nasa.gov/
http://www.vox.com/2014/12/11/7376103/mars-curiosity-lake
http://mars.nasa.gov/multimedia/images/?s=26
http://mars.nasa.gov/allaboutmars/mystique/history/1700/
http://marsmobile.jpl.nasa.gov/programmissions/missions/future/mars2020/
http://www.nasa.gov/press/2014/december/nasa-s-curiosity-rover-finds-clues-to-how-water-helped-shape-martian-landscape/#.VNrR8mIaySN
http://www.nasa.gov/mission_pages/MRO/news/mro20111102.html

- Jiaxuan Liu

String Theory - No Strings Attached

The mythical unified field theory, alternatively known (to the author) as the “should explain literally everything” theory, has eluded physicists since the dawn of time. To understand the basis for this, one must first understand what a field is. A field in physics is defined as a place in which a force can exist. Now, in recent years, physicists have managed to determine that there are four forces that govern all actions in our universe, those being gravity, electromagnetism, and the strong and weak nuclear forces. Today, we use the Standard Model simply because it explains the most in the simplest way possible, but even this theory cannot explain all four forces, as it is unable to explain gravity. The unified field theory, if it does exist, would be able to explain all four forces and how they react in a single, unified field; that is, it illustrates exactly how all four of these forces work and coexist in our universe. Today, we have a theory that, while technically not a theory, can explain our entire universe and everything going on inside of it.

String theory attempts to explain “life, the universe, and everything” by defining a universal single building block for every subatomic particle - the string. A string is a one-dimensional object that connects with itself, like a circle. Strings vibrate with specific waveforms at specific frequencies, generating different types of particles. Each string’s vibrations influence the other strings around it, creating what we perceive as the forces from interactions between particles. These strings also presumably interact through ten spatial dimensions, as opposed to our three spatial dimensions and one temporal dimension. The supposed reason for us never detecting the existence of these other six spatial dimensions is that these dimensions are collapsed and only detectable at the same scale as the strings themselves. There are structures called Calabi-Yau spaces that model how these dimensions entwine, each dictating ways in which strings resonate one another. Essentially, each Calabi-Yau space defines different rules and constants for the universe, because when the strings play differently, different particles and reactions are generated.

As a musician, I find string theory interesting that our universe’s rules could be dictated by what is essentially music. Every string is like a single instrument in the orchestra that would be our universe. When every instrument playing its part, the particles of our universe are created, and the interactions between the instrument sections create the forces between these particles. Each Calabi-Yau space is like a unique composition of this orchestra of strings, as each space defines the universe’s rules differently. It’s a somewhat obtuse metaphor, as the similarities are only superficial, but it is interesting enough to me that I can justify spending a paragraph on it.

Unfortunately, despite its ability to satisfy the requirements for a unified field theory, string theory has been dismissed by most physicists as a waste of time. This is primarily due to the fact that string theory is technically not a theory, because it can be neither verified nor falsified, essentially making it a moot claim. Theoretically, some time in the future we should be able to verify the existence of strings, but modern physics simply cannot monitor objects that small, nor can we monitor six more spatial dimensions that we cannot perceive or comprehend. However, with the current rate of advancement in technology, we should one day be able to perceive sizes this small and put string theory to the test.

- Jacob Lee

Are There Other Habitable Planets?

As the human population continues to rise, we must begin to think of alternative options for habitation. In the past 50 years, the human population has doubled from roughly 3.5 billion to 7 billion people, and is still growing at about 1.14% per year, roughly an increase of 100 million people per year. Therefore, space colonization may become necessary in the near future.

The natural first option is Mars. For years, NASA has been using rovers to navigate the surface of Mars to find signs of ancient life and water. A couple of years ago, signs of water in a lake were found on Mars by the rover Curiosity, which is a possible indicator of the past existence of microbial life. Ice has also been found on Mars in polar ice caps—which could possibly have liquid water beneath them. Yet, the possible existence of water is not enough to sustain life. The temperature on Mars is significantly lower than the temperature on Earth since it is further from the sun than Earth is. Also, the Mars’ atmosphere is thinner than the Earth’s atmosphere, which would lead to greater levels of UV radiation. Lastly, the distance is also a problem. While we may see Mars as fairly close, it is still around a six-month journey away from Earth with the technology that we currently possess. We are still quite a while away from having Mars as an option for space colonization.

An artist's rendition of the
Kepler Space Telescope

Scientists have also begun to look for planets that are similar to Earth that are farther away. The Kepler Space Telescope has been vital to this practice as its mission is to find planets outside our Solar System. So far, it has been successful, having found about 1000 confirmed exoplanets. Some of these planets are fairly Earth-like. Some of these planets are fairly Earth-like and lie within their stars’ habitable zones, the zones where water can exist in liquid form. The Earth Similarity Index (ESI) measures how physically similar a planet is to Earth. Recently, the most physically similar planet to Earth was found. Kepler 438b was found to have an ESI of 0.88, which is very high compared to Venus’ 0.78 and Mars’ 0.64. Unfortunately, Kepler 438b is 470 light years away from Earth, so it may never be inhabited by humans. Other Earth-like planets are closer. Kepler-298d, Kapteyn b, and Gilese 832c have ESIs of 0.68, 0.67, and 0.81 and distances of 11.9, 12.7, and 16.1 light years, respectively, making them more viable options for possible habitation.

While space colonization may not be necessary for the conceivable future, it is still potentially useful to find Earth-like planets now. Additionally, it provides some possible insight into extraterrestrial life that could be existing on these planets. Who knows what is out there to be found?

- Kevin Li

The Discovery of the Ever-Expanding Universe

For a long time people thought that the universe was unchanging and that the universe was just infinite and static.Even Albert Einstein himself believed in this idea so when he tried to solve this problem of what the universe was like, he assumed that the universe was static and his original solution had a constant called the cosmological constant. He later said that this was probably the biggest blunder in all of his work. Edwin Hubble started to observe the distance to galaxies. Hubble showed that the velocity of a galaxy increased as its distance to earth got farther and farther. This meant that the universe was in fact expanding and the farther away something is, the faster it appears to move away because of the universe expanding. Hubble actually used Vesto Slipher’s (the discoverer of galactic redshifts) observations of the redshift of galaxies, combined with his own observations to propose Hubble’s law and his idea of the expansion of the universe.

George Lemaitre also proposed the idea that the universe is ever-expanding and came to the realization that at some point it must have existed as a single point; and that was the birth of what is now called the Big Bang theory. Lemaitre argued that if you go far enough back in time the universe must have started as a single particle (the primeval atom). Lemaitre was also responsible for being the first to derive Hubble’s law as well as give an estimation of the Hubble Constant. He thought that the universe would never stop expanding. There are three possible different types of expanding universes. One would be that the universe is open meaning that it would just expand forever. The second type would be if the universe were flat. That would mean that the universe expands forever but at a certain point the expansion rate would slow down to zero after an infinite amount of time. However, if the universe were closed then it would stop expanding at a certain point and collapse on itself due to gravity.

The idea that the universe is infinite and in fact ever-expanding is a very interesting one. Since the universe is infinite and there are so many galaxies out there that we have never even come close to exploring there are an infinite number of possibilities of what is out there. There may be another parallel universe where there are humans living there like us, wondering if anything else is out there. That is why it is so important to continue exploring space and trying to find possible ways to reach other galaxies. If we were to find a way to travel fast enough that we could get to another galaxy in a lifetime we could very likely find other life out there. If we never actually take these steps to explore we could be missing out on a lot of different things. There is an infinite amount of possibilities of what could be out there and the faster that we can cover as much ground as possible the more likely we can discover extraterrestrial life.

- Eric Chow

Journey to the Stars: The Voyager Mission

It is an unfortunate fact that it remains nearly impossible for humans to physically travel beyond our neighboring space. As human beings, we are a puny entity compared to the vastness of the universe. Countless other worlds and galaxies lie far away, and much of astronomy is fundamentally rooted in learning about these grand wonders. One of the most significant and successful projects initiated for this task is the Voyager mission.

Conceived after the Mariner missions, the Voyager mission was officially approved in 1972, and the two probes, Voyager 1 and Voyager 2, were launched in 1977. Originally conceived to survey the gas giants of Jupiter, Saturn, Uranus, and Neptune, the two probes have since reached their intended missions and far surpassed them. The first target planet, Jupiter, was reached by Voyager 1 in 1979; Neptune was surveyed by Voyager 2 10 years later in 1989. One reason that allowed the pair of probes to travel so quickly was a rare planetary alignment that offered gravity assists, cutting down the mission time by more than 20 years. Since then, both probes have traveled far past our planetary system, and in 2012, Voyager 1 officially entered interstellar space.

As part of their mission, the two probes provided a wealth of information from the farther planets, especially regarding Jupiter and Saturn. What were previously thought to be uninteresting planets surprised scientists; it was found that one of Jupiter’s moons, Io, exhibited more than 10 times the amount of volcanic activity of Earth. Another moon, Europa, was hypothesized to contain a liquid ocean beneath its icy surface. Saturn’s rings, originally thought to be uniform, consisted of icy rocks of different shapes and sizes.

As Voyager 2 continued its flyby of Uranus and Neptune, it unveiled these previously mysterious planets. Meanwhile, Voyager 1 headed toward the edge of the solar system, heading into interstellar space, shortly joined by its twin. Interstellar space begins at the heliopause, where the solar wind and interstellar wind meet. The imaging systems of both probes were turned off in 1990 to prioritize battery life and memory usage.

The Voyager probes have now traveled for nearly 40 years; yet, it would take an estimated 85,000 more years for the probes to reach the nearest star system to our solar system, if they were heading in that direction. Despite being the farthest traveled manmade object, it is still barely a stone throw away in the cosmic sense. While some people may find this fact defeating, it also truly encapsulates how small we are and the presence that we hold in the universe around us. As Carl Sagan says, “Every one of us is, in the cosmic perspective, precious. If a human disagrees with you, let him live. In a hundred billion galaxies, you will not find another.” While the Voyager mission has told us new things about what lies beyond our planet, perhaps it can allow us to appreciate what we have here even more.

- Alex Du

Wormholes and the Potential for Time Travel

Nearly every person at some point in his or her life has encountered the idea of time travel. Whether in movies, comics, novels, or TV shows, the concept of time travel is pervasive in popular culture. In all likelihood, you have spent nights falling asleep to questions like “is time travel possible” and “what would time travel be like?” For a long time, these questions only existed in the realm of imagination and science fiction. However, now there is scientific reason to believe that time travel may some day, albeit some day a very long time from now, be possible. The discovery that wormholes, which are essentially short cuts through spacetime, are allowed under Einstein’s Theory of General Relativity has given a scientific backbone to the idea of time travel. Wormholes exist in regions of spacetime that are bent so that two distant points come in very close contact and become connected via a tunnel, or wormhole, through “hyperspace” (an imagined space that exists outside of spacetime). If someone were to be able to move through a wormhole, they would actually be moving faster than the speed of light, since it would take light longer to travel through spacetime between the two points than for an individual to pass through the wormhole. Furthermore, if one opening of the wormhole were sped up to nearly the speed of light time would slow down at that opening, and once the opening came to a stop again it would have experienced less time than the opening that was always stationary. This, essentially, would permit the wormhole to act as a time machine. Since time is connected between the two sides of the wormhole, someone who entered the side of the wormhole that had been accelerated (and had experienced less time) would leave the stationary side at that same time (i.e. some time that was in the stationary side’s past); conversely, if someone entered the stationary side (which had experienced more time), they would exit the accelerated side at that same time as well (i.e. some time that is in the accelerated side’s future).

The concept of wormholes and their potential for time travel was first introduced in 1916 when Ludwig Flamm found a solution to Albert Einstein’s field equations that allowed for such an occurrence in nature. It was Einstein and Nathan Rosen, however, who in the 1930s first studied the idea of wormholes intensively. The “Einstein-Rosen Bridges” that the scientists modeled would be in existence only briefly. In fact, “the wormhole throat would flicker in and out of existence so quickly that nothing – not even light – would have time to get through” (Toomey). The gravity of the wormhole would be so great that it would accelerate radiation, causing the wormhole to nearly instantly collapse on itself, and making any kind of transversal impossible. After Einstein and Rosen studied wormholes and had obtained these findings, wormholes did not receive very much attention within the field of astrophysics.

In 1988, with the publication of “Wormholes, Time Machines and the Weak Energy Condition”, Kip Thorne and Mike Morris reignited interest in wormholes and time travel. Thorne and Morris presented a situation in which a wormhole could remain open, therefore permitting time travel. Thorne and Morris showed that if a type of “exotic matter,” which has a negative energy and exhibits a repulsive force, was placed in the throat of the wormhole, then the throat could be held open for longer periods of time, allowing passage through the wormhole and time travel. Essentially what Thorne and Morris had done was “turn science fiction into science” (Toomey). Since this 1988 paper, research has been done that has further changed the perception of wormholes. Physicist Matt Visser has illustrated using string theory that a traversable wormhole could exist without exotic matter, in which it is held open by negative mass cosmic strings.

While many types of wormholes have been hypothesized, there remains no evidence for their actual existence. There is evidence of objects in the cosmos collapsing in on themselves to form black holes, but not wormholes. While it is speculated that small wormholes may exist in the 'quantum foam' with throats less than 10^-30 centimeters across, the most compelling evidence for them remains that their existence is allowed by the equations of general relativity. As Matt Visser has stated, the evidence for wormholes comes from the fact that “even though wormhole physics is speculative, the fundamental underlying physical theories, those of general relativity and quantum mechanics, are both well tested and generally accepted.” So as of today wormholes are entirely theoretical, and therefore the possibility of time travel is very distant. If we ever get to jump in a wormhole and travel through time and space like members of the USS Enterprise, it certainly will not happen for a very long time.

References: 

The New Time Travelers, by David Toomey
Black Holes, Wormholes, and Time Machines, by Jim Al-Khalili
“Time Travel and Wormholes: Physicist Kip Thorne's Wildest Theories,” by Calla Cofield
“What is a Wormhole?” by Nola Redd
“Wormholes”, by Dr. David Anderson

- Zachary Ettensohn

Scientists Prove the Possibility of Time Travel!?!?!? What You'll Read Will Amaze You...

A wormhole is a tunnel through the space-time continuum which allows for faster transit through the universe and the possibility of time travel. The theory of wormholes was created in 1934 by Albert Einstein and Nathan Rosen who used Einstein’s Theory of General Relativity to describe these bridges through space and time. Like the Holland Tunnel connecting New Jersey to Manhattan, a wormhole is a tunnel that would connect point A in the universe to point B. Imagine taking a map and folding it and then poking a hole through the center; this hole would be a wormhole. In warping space and time, wormholes provide a faster route from point A to point B in the vast universe. There are many different kinds of wormholes, like wormholes found in quantum foam which tend to be small tunnels. Meanwhile, Einstein-Rosen wormholes, like black holes, are massive and extremely dense celestial bodies that disrupt the fabric of space and time. It has been theorized that black holes themselves could be a form of wormholes.

The wormholes described have been theorized to connect two points in space, but they could also have the ability to connect two points in time itself. Einstein’s Theory of Relativity states that as objects begin to approach the speed of light, they distort time such that time runs slower for the object than it does for the object’s surroundings. Physicist Kip Thorne describes a hypothesis that would allow for time travel through a wormhole. In this example, there is a wormhole with one mouth on Earth and the other contained on a spaceship, attached kind of like a trailer to a truck. The spaceship travels for a few hours at speeds close to the speed of light, then heads back to Earth. This light travel ultimately creates a rift in time, as one end of the wormhole has traveled years in future due to the Theory of Relativity while the mouth that stayed on Earth is in current time. As a result, passing through this wormhole would be a way of traveling through time as you travel through one mouth in current time to another in the future.

Despite the great advancement wormholes would provide, it would be extremely hard to sustain one because wormholes are very unstable. They require large amounts of energy to hold them open, considering that they are tearing through the very fabric of space and time. Considering the amount of energy needed to keep a wormhole open, it is theorized that only wormholes would only be able to stay open if we pumped some sort of exotic matter into them. This exotic matter contains “negative energy density and a large negative pressure” (Redd). Thus, like the air inside of a balloon, this negative energy would be able to push outwards, negating the pressure pushing inwards that would ultimately force it to collapse on itself. Though these hypotheses have potential, the creation of a wormhole is far beyond the realm of our current technologies.

Sources: 

http://www.space.com/28000-physicist-kip-thorne-wildest-theories.html
http://www.space.com/20881-wormholes.html
http://www.andersoninstitute.com/wormholes.html
http://science.howstuffworks.com/science-vs-myth/everyday-myths/time-travel4.htm

- Andrew Afable