Saturday, May 2, 2015

Paradoxes of Time Travel

While time travel can sound fun and even plausible, we might run into some serious problems. These problems stem not from equations not being satisfied, but logic being broken. In this blog post, I am going to discuss three different types of paradoxes associating with traveling back in time as well as solutions to try and resolve these issues.

The first of these paradoxes is the bootstrap paradox, a paradox that is related to original information. This paradox does not necessarily change the course of history, but it does blur out the origin of the object in question. Let’s say I was to go into the future to learn about a single equation that can explain every phenomenon in the Universe and then told someone about it after I returned from my trip. That person may end up writing a book that contains information about that equation, which is why the future knows about that equation. In the end, we end questioning who and when this equation was made. 

Continuing on with paradoxes, the predestination paradox discusses the implications of changing an event in the past because of something that happened in the present. A classic example is of a man going back in time to save his girlfriend from a car accident. As he is in the past driving quickly to the eventual accident location, he hits his girlfriend, and kills her. He caused the death that made him travel back to the past in the first place.

The last paradox we are going to observe is the grandfather paradox, one of most well known paradoxes of time travel. It’s a pretty simple scenario; you go back in time to kill your grandfather. The problem to this is that if your grandfather is dead, then he wouldn’t be able to give birth to your parents. Without your parents existing, then you can’t exist. Yet you were able to travel back in time to kill your grandfather.

But we also have theories to put down these paradoxes. The Novikov self-consistency principle says that anything a time traveler does in the past, is already represented in the present time. This principle believes the Universe “prohibits” inconsistency, that free-will of a time traveler is limited when he/she travels. Another possibility is that maybe one does can do anything they want in the past. But changing anything in the past will lead to a different parallel Universe. By changing what you do in the past, you essentially split the universe into two scenarios. The future you are from will stay the same because that was already determined from the past. But your new change in the past, will create another world where the future will be different because of that change. So if you were to go back and somehow save the dinosaur species from extinction, there would still be no dinosaurs in the present day. This is because the instant you save the dinosaurs, you have essentially split the Universe to go on two alternative paths; one path with a world of dinos; another with just humans.

All in all, these paradoxes clash with the idea of traveling back in time. If we want to resolve these issues, we need to think outside the box, such as with Novikov self-consistency principle. Or we need to start finding evidence for parallel universes. These paradoxes pose more questions that physicists and astronomers need to answer. It creates more opportunities to learn and discover about new things.


"3 Time Travel Paradoxes!!" YouTube. YouTube. Web. 25 Apr. 2015.
"Time Travel Simulation Resolves." Scientific American Global RSS. Web. 25 Apr. 2015.
- Eric Lee

Friday, May 1, 2015

Dark Matter Detection

Along with the numerous proposed candidates for dark matter, many varying dark matter detection methods have been developed, too. Currently, most of the search is now directed towards weakly interacting massive particles, or WIMPs. The two methods of dark matter detection currently used are very different and as such revolve around completely different facilities, so they will be talked about separately. The most obvious method of proving the existence of dark matter is called direct detection, and it involves finding living WIMPs in a real environment. The other method, indirect detection, instead searches for the particles left behind by a decayed WIMP.

Direct detection generally involves large facilities working in large scales to increase the chance that a stray WIMP will be detected. There are two types of direct detection technologies currently used: cryogenic detectors and noble liquid detectors. Cryogenic detectors operate at temperatures close to absolute zero and are able to detect random particles hitting a crystal absorber by the heat they give off. One of the most famous cryogenic detectors is CDMS, or the Cryogenic Dark Matter Search. Despite the generic name, the program has had 11 possible detections of WIMPs, from 2009 to 2013. The other kind of detection technology, noble liquid detectors, are able to detect particles by the light they produce upon hitting a liquid noble gas, like xenon. Another famous noble liquid detector is LUX, the Large Underground Xenon experiment. LUX is able to detect WIMP collisions with xenon atoms, but also can distinguish neutron collisions with actual WIMP collisions. Both of these detection methods require very isolated facilities far underground to reduce the effect of cosmic rays on experiments.

Indirect detection hinges on the existing theories of supersymmetry and rely on the prior knowledge of a WIMP's construction and degradation. WIMPs should be able to decay into standard model particles, specifically gamma-rays, so many gamma-ray-capable space telescopes search for areas of high gamma-ray concentration. For instance, the Fermi Gamma-ray Space Telescope's discoveries posited that a large amount of gamma-ray radiation from the center of the Milky Way could be because of WIMP annihilation. Another experiment, PAMELA, found an abundance of positrons and cosmic rays, meaning it possibly witnessed WIMP annihilation, too.


CDMSCE @ UC Irvine
Shadow Universe by Corey S. Powell
- Jacob Lee

The History Recorded in Mars’ Meteorites

Mars resembles the Earth in many ways, including its day length, its temperature, and its gravity, thus many people consider the possibility that one day we may inhabit it. However, there are many mysteries that scientists would have to solve before determining whether Mars is capable of supporting life. If they ultimately show that life once existed on Mars, it will confirm that life can exist on other planets, even if might not be plausible for life to exist now or in the future on Mars itself. Scientists approach this question from several directions. One of them is studying the SNC meteorites, which originated on Mars.

Most of the meteorites from Mars fall into one of three groups –Shergotty, Nakhla, and Chassigny –thus people use the term SNC meteorites to refer to meteorites from Mars. These meteorites contain similar compositions and have similar structures, thus when petrologists first studied them, they speculated that they might have come from the same “parent body.” Even though they come from the same planet, they also differ in many ways. Most SNC meteorites belong to the shergottite category, which is a kind of basaltic meteorite consisting mostly of pyroxenes and relic plagioclases. Some of the Martian meteorites fall into the category of nakhlites. These meteorites are clinopyroxenes, which are monoclinic pyroxenes and are either calcic or sodic, and they contain augite, olivine abundant in iron, titanium-rich magnetite and interstitial and glassy material that was formed when the meteorite was formed. “The nakhlites have preserved some of the clearest traces of aqueous alteration within the parent rocks on Mars” (Martian Meteorites). Last but not least, chassigny is a cumulative of dunite, containing more than 90 percent of olivine, with pyroxene, chromite and plagioclase making up the rest (Martian Meteorites).

Since the SNC meteorites share so many similar features, researchers were certain that they originated on the same planet. They also speculated that they came from Mars, but not until 2000 were they confident that the SNC meteorites indeed originated on the Red Planet. According to Allan Treiman and his fellow researchers, the 14 SNC meteorites that were identified at that time “contained traces of gas which is similar in elemental and isotopic compositions to the modern Martian atmosphere as measured by Viking landers on Mars and spectroscopy from Earth.” Specifically, the EETA 79001, which is in the class of shergotite, is the first SNC meteorite that found to contain the compositions that were also identified on Mars. It has glass inclusions that contain rare nitrogen isotopic compositions, which was also found in the Martian atmosphere by the Viking spacecraft in 1976. As Treiman said, since Mars has such a unique composition, having a similar composition with it is a strong indication that the SNC meteorites came from Mars. If they are not from Mars, “it (the planet that SNC meteorites actually came from) would have to be substantially identical to Mars as it now is understood”, Treiman confirmed.

SpaceX vs. United Launch Alliance

Nowadays, SpaceX is known as one of the larger companies within the space travel industry. One of SpaceX’s main ventures is launching rockets. Of course, there are other launch companies who provide similar services. The largest competiting company is the United Launch Alliance (ULA), a 50-50 joint venture owned by Lockheed Martin and Boeing. Since ULA’s primary products are rockets that launch satellites or other objects into space, it is natural for them to be competitors of SpaceX. Currently, ULA has three rockets: the Atlas V, Delta II, and Delta IV, most of which are sold to the United States government. Controversy with arose in 2014 when SpaceX’s founder, Elon Musk, claimed that ULA rocket launches cost the government $460 million dollars each, opposed to SpaceX’s relatively low cost of $90 million dollars per launch. SpaceX protested by stating that the process for contracting the Air Force’s launches should be competitive, rather than uncontested, as ULA was being handed large launch contracts without the consideration of SpaceX (Leopold). ULA was not very happy about this, and responded by claiming that their launches were around $160 million dollars apiece (Gruss). Also, CEO Tory Bruno claimed that it was risky to rely on SpaceX for national security launches (Davenport). By trying to force their way into the more lucrative launching business, SpaceX is trying to gain more funding and to display their newfound strength in space travel. Even though ULA is newer, Lockheed Martin and Boeing are old and established companies that have much more history than SpaceX.

SpaceX's Falcon 9 on the left, and
ULA's Delta IV on the right.
Yet, SpaceX’s claims have managed to scare ULA into making some fairly drastic changes. These changes start with cutting launch costs in order to compete with SpaceX, as well as developing a new launch system. Unlike SpaceX, ULA buys many of its parts from other producers, which is problematic. This is because the RD-180 engine, used for the Atlas V, is made in Russia. Due to tense relations with Russia over affairs in Ukraine, the United States government has banned the RD-180 engine, leaving ULA with only five RD-180s for about forty launches through 2024 (Gruss). This is an important difference between SpaceX and ULA: SpaceX is unaffected by problems with suppliers, since they have the capabilities to manufacture their own products, while ULA is susceptible to restrictions and problems from external forces. This is how SpaceX will continue to keep their prices low, and why it will take a while for ULA to catch up to SpaceX, if they can even catch up.

That being said, ULA is also working on some projects of their own. One such project is to address the aforementioned problems with the engines. There are currently plans to develop a replacement engine for the RD-180, the BE-4, built by Amazon founder Jeff Bezos’ company, Blue Origin. There are currently plans for testing of the BE-4 in 2016, with the first flight being in 2019 (ULA). The BE-4 will be much stronger than SpaceX’s current Merlin 1D, with a planned thrust of 2,400 kilonewtons, which will be competitive with SpaceX’s planned Raptor engine. Another project that ULA is working on to compete with SpaceX is the Vulcan rocket. The Vulcan is planned to be much cheaper than the Delta and Atlas models that ULA currently uses (about $100 million dollars), and will use the BE-4 engine that is currently being developed (Clark). There are also some plans to have degree of reusability, perhaps using parachutes and helicopters to recover stages of rocket, but these ways would not be tested until the 2020s (Bruno). Clearly, the big unveiling used to display their plans is a way to relieve pressures from SpaceX as within a couple of years, SpaceX might not just be slightly ahead of ULA’s current capabilities—they might be far ahead.

Clearly, SpaceX fares well against ULA. By maintaining a low launch cost, SpaceX is more able to obtain launch contracts with companies as well as attract interest from the government. Also, when SpaceX is eventually to launch people to Mars reliably, a lower cost will mean that more people will be able to go to Mars and at a faster rate. This lower cost is due to their ability to make almost, if not everything, on their own. Another benefit is that they are extremely efficient in planning and building their projects. Currently, it has been 13 years since the inception of SpaceX, and within these 13 years, tremendous progress has been made to further space travel. From rockets to space capsules, SpaceX is beginning to take a leading position in the industry. Presumably, the smaller size of SpaceX allows for a more efficient workspace; all of the engineers are together in one place, so the development process is greatly streamlined. Therefore, the so-called competitors of SpaceX do not really pose any kind of immediate threat as they lack the capabilities that SpaceX currently possesses.

- Kevin Li

Sunday, April 26, 2015

The Great Schism(s)

For centuries, there has been a divide between religion, particularly Christianity, and science. Religion is very closely tied to Creationism, the ideology that asserts that life and the universe originated from a divine act performed by a divine being known as God. The opposite side subscribes to the scientific method, asserting there must be some sort of sufficient evidence to make any conclusions as to the creation of the universe or life. These differing ideas caused a rift between religion and science. However, in more recent decades the divide between the two has lessened with the rise of new ideas, such as Old Earth Creationism, that tries to bridge the gap.

Creationism is divided into two main belief systems: Old Earth Creationism and Young Earth Creationism. While there are differences between the two systems, for instance how much they accept scientific fact, they agree that there is some sort of divine intervention in the formation of the universe and the creation of life. The extent of divine intervention depends on the branch you choose. The major difference between Young and Old Earth Creationism is how they interpret the Bible. While Young Earth Creationism tends to interpret the Bible very literally, believing that the universe was created by God in a mere seven days, Old Earth Creationism does not believe in its literal interpretation. “A major problem [Old Earth Creationists] have with the literal interpretation of the Bible is that it does not fit the current scientific evidence” (Hitt). While the two different branches agree that there is divine intervention involved in the creation of everything, Old Earth Creationism recognizes the importance of science and empirical proof. Old Earth Creationism, unlike Young Earth Creationism, will not denounce findings or advancements in scientific knowledge. Instead, they try to incorporate these scientific discoveries within their beliefs. In recognizing science and its discoveries and evidence, Old Earth Creationists seem to be more of a bridge between science and religion.

Two branches of Old Earth Creationism are Gap Creationism and Day-Age Creationism. While the Bible writes that the universe was created over the course of seven days, Day-Age Creationists assert that every day described in the Bible is actually an indefinite amount of time, like an era of sorts. So one day could have been the paleontological era and each proceeding day was another era following that, leading up to the creation of man. Gap Creationism describes the creation of the universe as a cycle of creation followed by long periods of stability, cycling until humans were created.

Young Earth Creationism is closely tied to creation science and the claim that the Earth and the universe are six thousand years old. Young Earth Creationists assert that creation and evolution are both similar because they are events that cannot be tested and therefore cannot be proved or disproved. For Young Earth Creationists, the creation of the universe took six days and God rested on the seventh. Also, all humans are descendants of the creation of the first man and woman, Adam and Eve.

This dichotomy between Young and Old Earth Creationism greatly exemplifies the differing levels of faith within the church and Creationists in general. While on the one hand it appears that the gap between science and religion may be closing to a certain extent, it is still evident by the Young Earth Creationist ideology that the bridge may never be fully crossed and that science and religion will be forever divided.


Evolution Vs. Creationism: An Introduction by Eugenie Carol Scott
“Evolution, Creationism, Intelligent Design”
“The Evolution of Creationism in America” by Austin M. Hitt
“What is Wrong with Intelligent Design” by Elliott Sober
“Creationism and Evolution Beliefs Among College Students” by Ralph M. Barnes, Lesleh E. Keilholtz, Audrey L. Alberstadt
- Andrew Afable

Origins of the Universe: Creationism

While most scientists believe that the origin of the universe came in the form of a bang, there is also creationism, which is the belief that the universe, earth, and everything on it originated from specific divine acts. Creationists believe that a supernatural deity intervenes or at some point has intervened in the physical world. Creationism comes in two forms. The first is Young Earth Creationism (YEC) and the second is Old Earth Creationism (OEC).

Young Earth creationists believe that the Earth is approximately 6000 years old. These Young Earth creationists are the least scientifically minded among creationists because today we have evidence of life from millions of years ago and 6000 years is definitely not enough time for evolution to occur. They argue that scientific evidence can be used to support their own claims as much as it can be used to support evolutionist claims. YEC states that the Earth as we know it was created in six 24-hour days and that all people are descendents of the first two humans created, Adam and Eve. As the Bible states, the sins of Adam and Eve led to their expulsion from the Garden of Eden; eventually there was a flood where only the beings on Noah’s ark survived. YEC do argue that scientific evidence can be used to support their views and that this same evidence is actually just being interpreted unreasonably by evolutionists. They do believe in speciation but they think that it occurs much faster than what evolutionists think. They also argue that since our human history only spans a few thousand years, the world cannot be billions of years old because civilization would also be nearly as old. Also many different cultures throughout history have recorded evidence of some sort of big flood happening. They say because of this, the Great Flood must have actually happened.

The second form of Creationism is Old Earth Creationism. OEC states that God created the universe and the Earth billions of years ago. OEC actually uses modern science to help to prove their claims that the Earth is so old. Some Old Earth Creationists believe in something called the Gap Theory. In the Bible the first verse describes God creating the heaven and the earth, then the second verse describes the earth being formless and dark. Those that believe in the Gap Theory believe that there was a gap in time from the first verse to the second verse. According to the Gap Theory there was a battle between God and Lucifer that destroyed the surface of the earth causing it to be formless during this gap in time. This is also their explanation for the extinction of the dinosaurs. Obviously OEC takes into account more of modern science. Today we know that dinosaurs did in fact exist because we have found solid evidence. OEC takes evidence like this and offers an explanation for it which is something that YEC could not necessarily do. Other Old Earth Creationists believe in Progressive Creationism, which means that the six days that are referred to in the Bible were not actually 24-hour days but much longer than that. Each day can be interpreted as thousands or even millions of years. The popular belief is that God created the universe and the earth and then either just let evolution and natural selection run its course, or actually guided this evolution to where it is today. This of course parallels the scientific evidence we have for evolution. Although there is a lot of scientific evidence out there, there will always be religious people that believe that God is what created the universe. However some of these people try to incorporate modern science into their ideology and actually accept a lot of it. On the other hand some of these people do not believe that a lot of this scientific evidence actually tells us anything and do not accept a lot of scientific facts. 

- Eric Chow

A little bit about curvature singularities

If you have ever taken a science class in school, chances are you’ve heard of the following two concepts: black holes and the Big Bang Theory. Each of these concepts has given rise to a fundamental question that is yet to be answered by scientists. Regarding black holes: what could possibly be behind those big black voids? And as for the Big Bang Theory: what exactly existed prior to the big explosion? Our matter and energy must have come from something, somewhere.

An example of a curvature singularity.
In a black hole as such, spacetime is
curved infinitely and the singularity
lies in the center.
These two fundamental questions can be resolved by invoking the existence of spacetime singularities. A spacetime singularity (or gravitational singularity) is a spot where the curvature of spacetime and the quantities used to measure a gravitational field are infinite. Here, the classical laws of physics that we know and experience on a daily basis break down: gravity and matter behave in ways that we cannot predict.

It is believed that the center of a black hole contains a singularity, a single point that contains infinite mass in an infinitely small area. All the matter and energy that gets pulled into the black hole flows to this spot. The effects of gravity strengthen as you approach a black hole. At the singularity, gravity is infinite. The curvature of spacetime is therefore also infinite (since Einstein told us that gravity is the curve in spacetime).

The Big Bang Theory suggests that before the explosion, the beginning of our universe was itself a singularity. All of the matter and energy currently in our universe was concentrated in a space of zero volume. Since ρ = M/V, the density of our universe at that moment was infinite.

An example of a conical singularity.
Spacetime is flat, yet a singularity can
theoretically still exist.
Spacetime singularities can be thought of as both the end and the beginning of space and time. Before the Big Bang, everything was contained in one spot. When that exploded, space and time was created along with matter and energy. In this way, we can think of this singularity as the beginning. As for black holes, their singularities stretch time and space to the point where they rip the fabric of spacetime. In a sense, it is the end of space and time.

The type of singularity described above is fittingly named “curvature singularity.” Another type, dubbed the “conical singularity,” does not involve a curved space or gravity. In this situation, a flat space simply happens to have a hole (see Figure to the right). This type of singularity, however, has little physical importance. Astrophysicists are more interested in learning about curvature singularities as they are more relevant to black holes and the beginning of our universe.

There is much mystery surrounding spacetime singularities and, as a result, remain purely theoretical. Physicists have many interpretations of what a singularity is, or what it could be. However, physicists do generally agree that the term “singularity” refers to infinite quantities that are practically inconceivable to us today.

Uggla, Claes. "Spacetime Singularities." Einstein Online. Web. 23 Apr. 2015.
"Singularities - Black Holes and Wormholes - The Physics of the Universe." Singularities - Black Holes and Wormholes - The Physics of the Universe. N.p., n.d. Web. 23 Apr. 2015.
Curiel, Erik. "Singularities and Black Holes." Stanford University. Stanford University, 29 June 2009. Web. 23 Apr. 2015.
- Sarah Shy

Friday, April 24, 2015

Missions to Find Life on Mars

Mars is our nearest planetary neighbor that potentially housed life in the past or currently houses life. Therefore, it has been the destination of many missions that have attempted to find life within our Solar System. Numerous missions have, since the early 1960s, journeyed to the Red Planet to further our search for extraterrestrial life.

The Spirit and Opportunity rovers, which were part of the Mars Exploration Rover Mission, have immensely enhanced our understanding of the Martian environment. Since landing on Mars in January 2004, these rovers have made extensive geological and atmospheric observations. With their cameras, the rovers have been able to send over 100,000 color and high-resolution panoramic and microscopic images of Martian terrain, rocks and soil to Earth. The rovers, however, have also been able to analyze the Martian environment. The four spectrometers along with the rock abrasion tools on each rover have allowed us to gain insight into the chemical and mineralogical characteristics of Martian rocks and soil. While Opportunity is still currently exploring the surface of Mars, Spirit has not been active since 2010. Together, however, the rovers have explored the Eagle, Endurance, and Gusey craters (among others), and have found evidence of ancient Martian environments that were sculpted by volcanism, contained water, and that were habitable.

The Mars Express Orbiter, part of the Mars Express Mission, is another spacecraft currently exploring Mars. The Mars Express Orbiter has been analyzing the atmosphere and surface of Mars from polar orbit since 2003. It has researched Martian geology, atmosphere, and surface environment. Specifically, it has made efforts to better understand the history of water on Mars as well as the potential for life on Mars. Through its observations, the Mars Express has found evidence of glacial activity, explosive volcanism, and methane gas. These three characteristics all suggest that life may have existed, or currently exists, on Mars.

In addition to the Mars Express Orbiter and the Mars Exploration Rover Mission, the Mars Science Laboratory and Curiosity rover have contributed to our understanding of the Martian environment and the potential for Mars to house life. The Mars Science Laboratory, which carried the Curiosity rover, arrived at the Gale Carter on Mars in 2012. Curiosity then explored the surface of Mars, collecting and analyzing soil and rock in an attempt to find conditions and organic molecules that could support life. Using several instruments, including a laser, hydrogen detector, and spectrometer, Curiosity has analyzed many aspects of the Martian surface. Its laser vaporizes surface samples, with the resulting gasses sent to test chambers on the rover. In these chambers, Curiosity is able to analyze the elemental composition of the material, and identify carbon-containing compounds that indicate the possibility for life. Additionally, the rover investigates whether nitrogen, phosphorus, sulfur, and oxygen are present. Not only does Curiosity analyze the chemical composition of the Martian surface, it also measures the radiation levels of the planet, which determine its habitability. Curiosity has found a former streambed, found rocks containing elements that support life, and found methane emissions as well. Curiosity, therefore, has provided evidence that Mars had sustained life in the past, and may still support microbial life somewhere on the planet.

Spirit, Opportunity, Curiosity, and the Mars Express have all enhanced our understanding of whether Mars can support life, or if it has at least housed life in the past. These missions have all provided valuable information regarding the Martian surface and atmosphere that have furthered our understanding of life on Mars. With these ongoing missions, along with future mission such as the ExoMars program and Mars 2020, our understanding of the potential for other life within our Solar System will continue to grow.

- Zac Ettensohn

A Particular Universe: Quantum Theory and Multiverses

While the existence of other universes appears to be a difficult idea to grasp, it can be surprising that the most important part in proving their existence involves studying the smallest particles that exist. Simply stated, the study of quantum physics is a crucial part of our understanding of multiverses.

Perhaps the first thing we must understand about in quantum physics is that we don’t truly understand anything at all. More accurately, the only certain thing we are sure about quantum mechanics is uncertainty, as represented in the Heisenberg Uncertainty Principle. According to this principle, given a particle with two physical properties, the more certain we are of the value of one property implies the less we know about the other. In this case, we are particularly interested in the relationship between the position and momentum of an electron. According to the uncertainty principle, the more we accurately pinpoint an electron’s location, the less we know about its momentum, and vice-versa.

This statement brings us to an important part of quantum physics: the wave function. The wave function is the mathematical formula used to describe quantum objects. Unlike traditional formulas, however, the wave function does not provide concrete information about an electron, but probabilities of where the electron may lie. A standard example to illustrate the wave function is the firing of an electron gun toward a phosphorescent screen. After the gun is fired, the probability of the electron being in any given spot is reduced as time passes. However, when the electron hits the phosphorescent screen, the exact position of the electron is known again; this reset is known as the collapse of the wave function.

The Copenhagen Interpretation of the wave function states that a quantum particle does not exist in one state or another, but exists in all states at the same time. It is only when the particle is observed that it is “forced” to choose a state, which is what becomes observed. The implications of the Copenhagen Interpretation are well described in the phenomenon of Schrodinger’s quantum cat. In this thought experiment, there exists a box, split in half, with a single electron as well as a cat. Along with this cat, there exists an explosive. If the electron is found on the same side as the cat, the explosive detonates and the cat dies. Otherwise, the cat stays alive. According to the Copenhagen Interpretation, as long as the box remains closed, the cat is both dead and alive at the same time, also known as a superposition of states. If the two halves of the box are separated, and placed at opposite ends of the world, this duality continues to exist. It is only when the box is opened, and the wave function collapses, that we can determine the state of the cat.

The Many Worlds Interpretation, proposed by physicist Hugh Everett, was first thought of by Everett when he was wondering what would happen if the wave function never collapsed, even upon opening the quantum box. According to his interpretation of the wave function, Everett states that when the box is opened, the universe splits into two separate universes: one where the cat is alive, and the other where it is dead. This philosophy can then be extended such that every time the universe is faced with a quantum decision, it is split such that a universe exists where that decision is made, and another where the decision is not made. Succinctly stated, this phenomenon implies that every possible state of the universe exists, leading us to modern propositions of multiverse theory.


Gribbin, John. In Search of the Multiverse. London: Allen Lane, 2009.
Kaku, Michio. Parallel Worlds: A Journey through Creation, Higher Dimensions, and the Future of the Cosmos. New York: Doubleday, 2005.
- Alex Du

Tuesday, April 14, 2015

A Possible Site For the Origin of Life

Scientists have proposed different theories about where life originated. Proposed sites for life’s origin range from deep sea thermal vents to subglacial lakes to exoplanets. Today I will introduce one of the theories, the “hydrothermal vent” theory.

Before introducing this theory for the origin of life, I would like to first introduce the concept of “extremophiles.” Extremophiles are organisms that can survive in and even favor extreme environments. For example, there are thermophiles that can thrive at temperatures between 45–122 °C, and xerophiles that can grow in extremely dry conditions. Since these extremophiles can live in such environments, they indicate the range of conditions suitable for life, and thus they provide precious clues for scientists who are investigating the possible environments in which life may have originated.

Hydrothermal vents

The proponents of the hydrothermal theory believe that the complex, high-pressure environment around deep-ocean vents may have been where life began. In 1977, a warm spring on the seafloor hosting a rich ecosystem was discovered by researchers using the submarine Alvin. Two years later, researchers on-board Alvin found a hydrothermal vent, an ancient chimney-like structure that enriched the surrounding seawater with minerals and heated it to 340°C. Around the vent was a prosperous biological community, which was unexpected because of the lack of sunlight and the extreme water pressure. Before the discovery, most scientists thought that life could not exist without the energy of the sun. However, this oasis had rich amounts of clams, crabs, sea anemones, and bacteria which have evolved their own ways to survive in the deep, cold environment without exposure to daylight. Because this discovery was totally unexpected, many scientists began to consider whether hydrothermal vents were where life might have originated on earth.

Therefore, these scientists started to carefully investigate the organisms living in the ecosystem around the hydrothermal vents. These organisms are thermophiles. During the investigation, the scientists found a thermophilic bacteria, A. Pyrophilus, that seems to be the closest living relative to LUCA (the Last Universal Common Ancestor). This finding suggests that life might originally have arisen under high-temperature conditions, perhaps in deep-sea hydrothermal vents.

The existence of organisms that are able to survive under extreme conditions has given scientists added motivation to explore the mystery of the origin of life. By understanding and researching extremophiles, scientists might be able to find the truth of the origin of life.

- Cora Wu

Monday, April 13, 2015

E.T. Leave Home

The prospect of extraterrestrial life intrigues us, as the idea that we are the only living organisms in the universe seems improbable, especially given the large number of planets in the universe. However, it is troubling that we have yet to come in contact with any extraterrestrial biosignatures, which could mean a multitude of things regarding both the existence of extraterrestrials and, if they exist, the level of their intelligence.

Enrico Fermi asked the question “Where is everybody,” referring to our lack of contact with extraterrestrial life. Fermi’s paradox argues that there is a contradiction between the high probability that extraterrestrial life exists and our lack of contact with it. This is especially true in that Earth and the Sun are relatively young in comparison to other planets and stars which populate the galaxy. Given the plausible timescales of colonization, we should be surrounded by colonized planets and moons. This leads some to believe that intelligent extraterrestrial life either does not exist or wishes to remain unknown to us.

This lack of contact with extraterrestrial life could lead us to believe that extraterrestrial life, if it exists, may not be advanced. Instead of thinking about a stereotypical alien with futuristic technologies, such as a Martian piloting a U.F.O, that alien could very well be a microscopic organism such as a bacterium that thrives in inhospitable climates, like Earth’s extremophiles do. The existence of extremophiles on Earth has made us rethink where life could exist elsewhere in the universe. Planets very similar to Earth’s habitability are no longer the only places for where life could exist. Scientists have recently proposed that there could be methane-based, oxygen-free extraterrestrial life, further showing how different extraterrestrial life may be compared to Earth’s.

Research in the field of astrobiology is still young and there is still much debate on what materials are required for life. The main hindrance is that we can only study life on Earth, which shouldn’t be extrapolated across the entire universe, as life may exist in forms that we have yet to imagine. The first extremophiles were only discovered fairly recently, in the 1970s, and perhaps there are more species yet to be found. Extraterrestrial life may exist in ways we wouldn’t think are possible.

Also, the ways that we search for extraterrestrial life are influenced by the technologies that we have, but perhaps aliens use technologies that we cannot even envision. Until we broaden our methods of searching, it may continue to be unfruitful. For instance, NASA's James Webb Space Telescope, or JWST, will directly observe the atmospheres of nearby "super-Earth" alien planets, searching for the chemical signatures of extraterrestrial life. As our technology continues to develop, we will be able to detect biosignatures of exoplanets remotely and eventually we will be able to visit those exoplanets to confirm the existence of extraterrestrial life. We shouldn’t get disheartened now, since it our technology is still very lacking and the prospect of extraterrestrial life is very high. If it exists, we will be able to find it eventually given sufficient resources and time.


After the Big Bang: the Formation of Galaxies

Astronomers in the latter half of the 20th century were able to make groundbreaking discoveries that expanded our understanding of the universe. We now have achieved a better understanding of how the universe may have came into existence and of the broad outlines of the Universe's evolution. However, despite these great discoveries, fundamental questions like how the first galaxies came about still remain unanswered.

Although we do not know how the universe came into existence, we do know from the Big Bang theory that 10-6 seconds after the "bang" that brought space and matter into being, protons and neutrons began to form, and twenty minutes later the universe was filled with hydrogen and helium ions. During the first 50,000 years after the "bang," the universe experienced a radiation-dominated era, where photons dominated matter and kept structures from forming. For several hundred thousand years immediately after, the universe was too hot for elements to form. The universe existed as a mix of subatomic particles and radiation. The first hydrogen and helium atoms did not form until the universe cooled to the point where the matter became transparent to the radiation. Waves of radiation stretched and diluted until they made a faint glow of microwaves which filled the entire universe. Images taken by NASA's Cosmic Background Explorer show maps of the slight differences from the mean temperature from one location to another that are now believed to be the first signs of structure. However, we do not know whether these subtle variations are the beginnings of the formation of the first galaxies.

Many theories have been proposed about the formation of galaxies. Many astronomers used to believe that the universe broke into large clumps that contained enough building materials to make structures like great walls and sheets of millions of galaxies. Continuous fragmentation would have produced smaller and smaller clumps which would finally "give birth" to individual galaxies such as our Milky Way and neighboring galaxies like the Large and Small Magellanic Clouds. Such clumps have been photographed by the Hubble Space Telescope and were speculated to be possible explanations to the formation of modern galaxies. However, simulations of the universe's evolution have shown that this "top-down" theory of structure formation is not plausible. Instead, the vast majority of astronomers now suppose the universe was formed by small pieces of gas clouds and star clusters that merged over time to form galaxies and clusters of galaxies. The first structures to form were quasars, luminous regions around super-massive black holes, and stars that were completely made out of hydrogen and helium. Then star clusters merged to form the bulges of galaxies, which then accumulated more gas and dust to form flatten disks with spiral arms. Smaller galaxies merged with bigger ones; gravity attracted galaxies to the groups, clusters, and even superclusters we observe today.

- Alice Zhang

Friday, April 10, 2015

The Big Bulk

The leading theory for the expansion of the universe after the bang is called the Big Bang Theory. Hubble discovered that the universe is expanding and then George Lemaitre used Hubble’s findings to extrapolate that at some point in time there must have been a single point where everything started. This bang was said to have been an explosion of space and time, which then brings the question, what was there before this bang and what is described in the Big Bang Theory? Also what really is this bang and how did it begin?

These questions drove Paul Steinhardt and Neil Turok to try and develop a theory of the events that led up to this bang as a supplement to the ideas of the Big Bang Theory. Their idea begins with a model that looked at the universe as a brane, which is a three-dimensional world that lies within a higher-dimensional space. A good way to visual what a brane is, is to image a sheet of paper flapping in the wind. The paper may be thought of as a two-dimensional object in a three-dimensional world. Both Steinhardt and Turok compared the piece of paper to our universe, except our Universe is three-dimensional inside of a four-dimensional background which they called the “bulk.” With this hypothesis they theorize that there were more than one brane in the bulk, just like there could be more than one piece of paper flying around in the wind.

This is where the Big Bulk theory starts to have similarities with and ties to the Big Bang Theory. If two branes, each holding a massive amount of energy, collided, the result would resemble that of an explosion. The theoretical characteristics of the explosion are actually quite similar to what we think the bang would have been like which is why the most important part of the Big Bulk Theory is how it helps explain what preceded the Big Bang Theory. Years later Steinhardt and Turok discovered something else about their Big Bulk Theory. After the collision, the brane world energy gives rise to matter such as galaxies, stars, and planets like our Earth. After the collision the branes start to expand and keep on expanding until the space between them is nearly empty. What’s interesting is that when that point is reached there are attractive forces that draw the world-sheets back together together, causing a collision that resets our Universe with another bang. The time between cycles would be roughly one trillion years. This idea of a cyclical universe also explains some gaps in the Big Bang Theory. In the Big Bang Theory which theoretically occurred 13.7 billion years ago, we do not know what time was before the bang or even if it existed. At this point in time we still do not know much about time and if it will one day come to an end or expire. The bulk theory could supplement the Big Bang Theory and explain what came before the bang and what eventually will happen to our universe.

- Eric Chow

A Fraction of Life

Life is a series of decisions. Every movement made can be represented as an action that is taken or not taken: a combination of decisions based on probabilities. This philosophy can be similarly extended to the particle realm; all particles are arranged in a certain, fixed position at any given time. At the intersection of astrophysics and philosophy, the existence of a fixed state gives rise to the idea of a level III multiverse.

Out of the four multiverse hypotheses, the level III multiverse has generated the most controversy despite being, on a cursory level, the most elementary. Simply phrased, the existence of a level III multiverse is based on the theory that all states of the universe exist in some abstract space. Whereas in the other levels, parallel universes are theorized to be located in regions of space unobservable to us, the level III multiverse can be thought of as states all around us, yet in a different dimension beyond our comprehension. While it may appear that there are an infinite amount of states, the amount of mass-energy in the Hubble volume—or the observable universe—leads to a different belief. Since there are a finite amount of particles that exist, there must be a finite amount of ways these particles can be placed. These states are all static and what we—as humans—observe as time and change can instead be thought of as a smooth series of shifts from one state of the universe to another.

The idea of testing for the existence of a level III multiverse has been pondered over by many. Perhaps the most morbid speculated experiment is quantum suicide. The premise behind the experiment is the existence of a life-terminating device, such as a gun, held to a subject. Every ten seconds, the gun is either fired and the subject dies, or is not fired, providing another ten seconds before the next shot. If all possible static states of the universe indeed exist, then in some state, the gun will not fire for an infinite amount of time. Therefore, the longer the subject exists, the more credibility the theory gains.

While the scientific basis behind this theory is far from fully established, the possibility of a level III multiverse has many interesting philosophical implications. Assuming the existence of a level III multiverse to be true, the idea of one can be said to hold similar ideals to those people that believe in fate. With every possibility already existing, proponents of this belief would claim that any action we make is predetermined. In a similar vein, the opposite viewpoint can also be supported by the existence of a level III multiverse. As people living only in the present, there are an uncountable amount of other copies of “us,” each having made different decisions and having experienced different lives. Perhaps this tells us that rather than subjecting our experiences to a predetermined life, it can be said all versions of “us” are experiencing every possible decision there is to make: both good and bad.

- Alex Du

Interstellar Travel

The 2014 movie Interstellar, directed by Christopher Nolan, intrigued its audience with the possibility of interstellar travel. However, while the movie utilized a mysterious wormhole that appeared near Saturn, the possibility of such a wormhole appearing at such a convenient place and connecting to a suitable stellar system is not very high. Thus, in order to realistically engage in interstellar travel, humans will need some method of transportation that will allow them to travel at nearly the speed of light.

Currently, all spacecraft use chemically propelled rockets for launch and most vehicles use such rockets for interplanetary travel. However, to reach Alpha Centauri, the nearest star system, using chemical rockets would take around 165,000 years. However, new technologies such as nuclear fusion rockets, interstellar ramjets, solar sail ships, and antimatter rockets offer the possibility of future interstellar travel.

Humans have yet to perfect nuclear fusion technology, but some are hopeful that in the next ten to twenty years, it will not only become commonplace, but also will be able to be used to propel spacecraft. The energy released by fusing light elements such as helium and deuterium has the potential to power a spacecraft to 10% of the speed of light.

The interstellar ramjet, which utilizes nuclear fusion, is an interesting concept first developed in 1960 by Robert W. Bussard. Instead of carrying fuel for travel, ramjets collect hydrogen atoms in space, fuse them, and expel the final products out the back. Although this concept is appealing because of the lack of need to carry fuel for long-distance journeys, there are certain technical issues associated with building such a spacecraft, including the difficulty in fusing interstellar hydrogen. This makes it unlikely that a ramjet will be built in the near future.

Solar sailships, on the other hand, have already been designed and some are in the process of being built. These sailships intend to use the energy emitted from the sun to propel the spacecraft forward. One solar sailship called Sunjammer was set to launch in 2014. NASA planned on using it to better detect oncoming solar flares. However, after Sunjammer’s contract with NASA was up, NASA pulled the plug due to lack of confidence that the Sunjammer would fulfill NASA's goals. The next date set by NASA to launch this project is around 2018.

Antimatter rockets are by far one of the more farfetched proposals of interstellar propulsion. Although humans have detected antimatter in particle detectors and when cosmic rays strike the atmosphere, there is still the issue of designing a system for storing it. Although antimatter might just be a science fiction dream, should humans achieve such a project, the energy released from antimatter rockets would be enough to theoretically accelerate a spacecraft to near the speed of light.

- Siqi Yang

The Meaning of the Heavens to the Mayans

The Mayan civilization of pre-Columbian Central America was obsessed with the cosmos. Astronomy was part of the daily lives of the Mayan people, influencing everything from their religion to their mathematics. Their knowledge of astronomy was very advanced for their time: they had extremely accurate calendars and were able to predict eclipses hundreds of years in advance. They tracked the movements of the Sun, the Moon, Venus, and groups of stars because they believed that such tracking had meaning in their lives. For example, when Venus rose in the mornings it was believed to be bad luck, so everyone would stay inside and seal their chimneys so that the evil light from Venus would not enter.

The Mayan religion revolved around the Sun, the Moon, and Venus. The Sun was believed to be one of their most powerful gods, Kinich Ahau, the father of all Mayans. The Moon was Ix Chel, a goddess that was as powerful as the Kinich Ahau. She represented fertility; the Mayans believed that nights that had a crescent Moon were the best for procreation and that after nine full moons one gave birth. Venus was Kukulkan, the god of strength and war. Warfare would be arranged to coincide with the movements of Venus and captured warriors and leaders would likewise be sacrificed at times dictated by the position of Venus in the night sky. Other gods were represented by star groups like the Pleiades star cluster, which portrayed the god of planting because when it rose during the morning in mid May the Mayans knew it was time to plant corn.

The Mayan's fascination with astronomy motivated them to revolutionize mathematics, including the creation of the zero. Mayan mathematics was created to be able to keep track of the movement of the heavens; with it they could record and predict the movements of stellar objects hundreds of years in advance. To help their astronomical calculations, the Mayans came up with the concept of zero before its invention in India. Instead of using a decimal system they used a vigesimal system, meaning it base 20 rather than base 10. Just as in the decimal system we have 1, 10, 100, 1000, etc., in the vigesimal system goes 1, 20, 400, 8000, etc.; the Mayans, however, did modify the system slightly, replacing the 400 with 360 to ease astronomical calculations involving the Sun. They also used astronomy to design their buildings. They aligned their temples to help observers monitor the position of celestial objects, like the Sun or Venus.

The heavens ruled the Mayan world, dictating a range of decisions from when to procreate to when to plant crops. Each object in the sky was meticulously tracked and recorded, and those records were used to predict important future events such as eclipses or when the Pleiades would rise. To the Mayans, astronomy was more than a hobby: it dictated their lives.

- José Uribe

Friday, April 3, 2015

The Conditions Needed for Other Life in Our Solar System

Does life exist elsewhere within our Solar System? Many people believe that life must exist somewhere else within our universe, but the question of whether other life exists within our Solar System remains unanswered. It is already known from studies on Earth that life can exist in extremely harsh conditions. Some microorganisms, known as extremophiles, have been found to thrive in conditions previously thought to be unsuitable for life. These organisms can live in water buried by sheets of ice in the Antarctic, or near incredibly hot thermal vents on the floor of the ocean. The fact that life can exist in such conditions gives new hope to the possibility of other life within our Solar System. At the same time, however, there are certain features required for extraterrestrial life to exist.

There are several characteristics regarding the composition of planets and moons that are required for them to sustain life. Perhaps most importantly, water is believed to be necessary. Life as we know it is based upon molecules and molecular interactions, and water is a medium that effectively allows life-sustaining chemical reactions to take place. Additionally, water’s high heat capacity and ability to expand when frozen allows it to help maintain a stable environment in which life can exist. In addition to water, however, many astrobiologists believe that carbon and other heavy elements must be present. Carbon’s unique ability to form a variety of chemical bonds and therefore create a diverse set of organic molecules allows for the establishment and growth of life.

In addition to the chemical properties of the planet or moon, it is also required that it be made of rock and be of a specific size. As opposed to a gaseous environment, a solid planet or moon has the potential for tectonic plates that create geothermal energy and recycle the raw materials on the surface. Relatedly, the size of the planet or moon is also extremely important. A planet that is too small will not have a molten core with tectonic plates or a magnetic field, nor will it have an atmosphere capable of protecting inhabitants from radiation. A planet that is too large, however, will have too heavy an atmosphere, which may prevent liquid water from existing. Planets or moons that support life will have a size within an optimal range, which astronomers estimate is somewhere between 0.2-10 Earth masses.

It is not only its composition that determines a planet’s or moon’s ability to host life, however. The position of the object in space is also vital. It is important that the planet exists within a “habitable zone” of its stellar system, or near another large planet. This habitable zone exists a certain distance from the central star, where planets and moons are far enough from the star to avoid high temperatures and radiation, but not so distant that they are extremely cold and frozen. Within our Solar System, astronomers estimate that the habitable zone ranges approximately from .95 to 1.4 astronomical units from the sun. Within the habitable zone, however, many planets or moons can still fail to sustain life. It is possible, for instance, that a planet can be tidally locked in orbit. In this case the side of the planet facing the central star would be too hot to support life, while the other side would be too cold. It is possible, however, for moons orbiting extremely large planets that are outside of the habitable zone to sustain life. In some cases the strong gravitational forces exerted by the planet on its moon cause it to have a molten core, and therefore support subsurface life, such as in salty oceans covered in ice. Therefore, while the habitable zone is a good indicator of where life could potentially exist, it remains a possibility for life to develop outside of it.

In our continuing search for life within our Solar System, we have determined that life can only exist in certain places. We know that there must be a specific composition of the planet or moon to be able to support life, and that it likely will exist within the habitable zone or near a large planet. Research within our Solar System has suggested that there is potential for life on Mars, Europa, and Enceladus, but further studies must be done before we can make any conclusions. Nevertheless, our expanding knowledge about what is required for life to exist gives us a basis off of which we can narrow and perfect our search for extraterrestrial life.

- Zac Ettensohn

A Certain Theory of the Unobservable Universe(s)

Uniqueness is a very arbitrarily used word. Statistics shows that the probability of you being born exactly as you are is 1 in 102685000, which is practically zero. So you could assert that you are pretty unique, in this world. However, in an infinite universe that is ever-expanding, there are infinitely many worlds in the parts you cannot see, and, therefore, infinitely many versions of you. This idea is more formally known as a Level I multiverse.

The Level I multiverse theory involves the idea that if the size of the universe approaches infinity, portions of will be repeated, over and over again. Therefore, there can be an infinite number of Earths populated with copies of you. However, there can still be differences between these worlds because there are an infinite number of possible histories for these worlds. For instance, in one of these worlds, World War II never happened, and in another you decided to wear a blue shirt today instead of a green one.

The Level II multiverse theory involves the idea that our universe is a single bubble in a sea of other universal bubbles known as the multiverse. It is a bit like bubble wrap, in which each individual bubble is its own universe. The bubble universe is founded upon the notion that different parts of the multiverse are expanding and inflating at different rates and times. Thus, when one part of the multiverse ceases to inflate, a pocket, or bubble universe, is formed. In the multiverse, the bubble universes can overlap with one another. Though we cannot pass into a neighboring universe, these universes can interact with one another, whether it be through gravitational or wave-like interactions as some electromagnetic waves may be able to pass into other dimensions. Finally, the physical laws that govern each bubble in the multiverse could be vastly different. For example, perhaps in one of these universes the speed of light is slower because of the bubble’s different laws of physics.

In the Level III multiverse theory, every decision we make creates an alternate universe. Thus, things that we attribute to random chance are actually not random at all. For example, every time we roll a die, we know that there is a one out of six chance that we will observe a four. However, in this multiverse theory, we will observe every alternative option, so while we thought we randomly rolled a four, in actuality, we split the universe into six parallel universes, each observing a different number. As a result, all outcomes are achieved, just in different, parallel universes. Every decision we make splits the universe into another parallel universe. So if we choose to turn left one day instead of right, the universe splits and there is now an alternate universe where you turned right instead. This also works for larger decisions in life. For instance, you are given three job offers: one, two, and three. In one universe, you choose one, and you meet your future soul mate, and you two eventually die as a happy old couple. In another universe, you choose job two, where you are highly stressed all the time, and eventually die prematurely of a heart-attack. Finally, in another universe you pick job three where you get divorced seventeen times and never experience true happiness. In essence, every decision we make affects the universe and ultimately could change the outcomes of our lives.

So maybe you are unique. In this world, universal pocket, or parallel universe, at least, you are unique. While the multiverse theories may be intriguing, there is no definite way to test any of them. So perhaps they will forever stay untested theories, and you will forever stay unique.

- Andrew Afable

Tuesday, March 31, 2015

How Did the Universe Begin?

Discoveries in astronomy and physics show the universe had a beginning 13.7 billion years ago. Prior to that moment, there was perhaps nothing but during and after the moment, our universe came into existence for reasons we still do not understand. The Big Bang theory tries to explain what happened during and after the moment. Astronomers speculate that our universe sprang into existence as "singularity," which are regions of infinite mass density that defy our current understanding of physics. However, no one knows what or where that singularity came from. What we do know is that volume of the universe inflated to huge sizes in the fraction of a second after the "bang" occurred. The temperature of the universe one second after it began was 10 billion degrees Fahrenheit. As the universe continued to expand, it continued to cool down, allowing the formation of fundamental particles like neutrons, electrons, and protons that decayed and/or combined to form the cosmos that we know today.

Although the Big Bang theory is widely accepted as the explanation of what happened after the "bang" that began our universe, it does not offer explanation for "bang" itself. Some theories attempting to explain the cause of the Big Bang include the oscillating universe theory and the chaotic inflation theory. The oscillation theory builds upon the Big Bang theory in that it believes the universe starts with a Big Bang, experiences a Big Crunch and repeats the cycle again with another Big Bang. Therefore, the Big Bang that occurred 13.7 billion years ago was just another step in the continuous cycle. Stanford physicist Andrei Linde also proposed a different possible explanation in the 1980s: chaotic inflation. Linde considered the possibility that the Big Bang may have been "a scattered and irregular inflation" that occurred wherever the right potential energy was available instead of being a single event. The Cosmic Microwave Background findings in the 1990s in fact showed variations of intensity that provided supporting evidence for the chaotic inflation theory.

While predictions from the Big Bang have been supported by observations, one of the main problems with the theory is that the temperature of the universe is nearly uniform. If the Big Bang marked the beginning of the universe, then according to some explanations, there has not been enough for the universe to reach the temperature equilibrium. Instead, the most plausible explanation for that uniformity is that, soon after the beginning of time, some unknown form of energy made the universe inflate at a rate faster than the speed of light so that the temperature in the inflated cosmos would be nearly the same everywhere. Alternative theories to inflation supported by the Big Bang explain this problem. For example, a group of theoretical physicists proposed a new theory that the beginning of the universe could have happened after a four-dimensional star collapsed into a black hole and ejected debris. Their reason to doubt the Big Bang theory is that “the Big Bang was so chaotic, it’s not clear there would have been even a small homogenous patch for inflation to start working on.” Instead, they proposed a theory in which the three-dimensional universe floats as a membrane in a four-dimensional "bulk universe." Since the bulk universe has four-dimensional stars, the stars go through the same life cycles as three-dimensional ones and when the massive ones explode as supernovae, their innermost parts collapse as a black hole and create a three-dimensional membrane surrounding the boundary between the inside and the outside of the four- dimensional black hole, the event horizon. Then, expansion would occur as a result of the three-dimensional membrane's growth. While this is an interesting possibility of the "bang" and the short period after it, the main question that must be asked of this or any other alternative theory is whether it provides testable predictions. It is ultimately only through observations that we know how the universe began.

- Alice Zhang

Friday, March 27, 2015

The Origin of Life on Earth

How life originated on Earth is a question that scientists have studied for centuries. Today, two leading theories for life's origin are abiogenesis, in which life arose naturally by chemical reactions, and panspermia, in which life arrived on Earth from elsewhere.

Before introducing the abiogenesis hypothesis, I would like to talk about the spontaneous generation theory that states that life arises suddenly and spontaneously from lifeless material. People before the 19th century believed fervently in the spontaneous generation theory. For instance, people observed that worms would be produced in a sealed bag of garbage, not realizing that worm eggs had gotten into the garbage before the bag was sealed. It was during the 19th century that Louis Pasteur designed experiments that proved that living organisms cannot arise from non-living material. Thus, the spontaneous generation idea was refuted.

The abiogenesis theory is also called the chemical evolution theory. Like spontaneous generation, it says that life arises naturally from lifeless materials. However, the timescales over which life forms is much longer than that of the spontaneous generation theory. In other words, in abiogenesis, life arises in a series of chemical reactions that do not occur suddenly. The first life must been extremely simple forms such as small organic molecules, which combined to form larger biomolecules, and then combined to create primitive living organisms.

The panspermia theory is very different from the abiogenesis theory; it maintains that microscopic living organisms were initially carried to Earth by an asteroid or comet. In other words, primitive life originated naturally in an extraterrestrial environment and then landed on Earth. However, this hypothesis is not viewed favorably by most scientists, who argue that outer space itself is too harsh an environment to allow unprotected cells to survive over a long period of time. Thus, a theory related to panspermia called "weak panspermia" is more popular. The idea states that it was not cells, but only ingredients of life, such as organic molecules, that were delivered from space. Evidence for weak panspermia includes the Murchison meteorite, which contains over 14,000 different molecules that would be capable of helping to spawn life. The evidence not only shows the presence of organic components in outer space, but also points to the ability of these materials to reach Earth.

The theories of the origin of life on Earth remain debatable, but they are worth pondering.


The Mayan Calendar

The Mayans are an incredible civilization that achieved amazing feats in science and astronomy; one of them was the development of the Mayan calendar. The Mayans were a pre-Columbian civilization located in Central America that was obsessed with the cosmos. That obsession influenced everything from their pyramids (which each had four 91-step staircases and a platform on top, making 365 steps in all) to when they were going to plant and harvest. Their astronomical knowledge was extremely advanced for their time; for example, they could predict solar eclipses and solstices hundreds of years in advance. For example, Harvey Bricker, author of "Astronomy in the Maya Codices," found a Mayan calendar that dated to the 11th or 12th century that accurately predicted a solar eclipse to within a day in 1991, centuries after the Mayan civilization had ended.

The Mayan calendar dates back to the 5th century BC and is still in use today in a few Mayan communities. The Mayan calendar actually does not consist of one but rather of three calendars: the Tzolkin, the Haab, and the Long Count. The Tzolkin is the divine calendar that consists of 260 days, divided into 20 periods of 13 days each. It was used to determine the time for religious ceremonies and it is related to nine moon cycles and the zenith of the Sun. The Haab is a 365 days solar calendar that is divided into 18 months of 20 days each and one month of five days. There is evidence that they knew that a year was not exactly 365 days but their primitive numerical system did not allow them to calculate the exact length of a year. The Long Count is an astronomical calendar that was used to calculate longer periods of time since the other two restarted every 52 years. The Long Count had a period of 1,870,756 days (5,125.36 solar years) or 13 b'ak'tuns, which was referred to as the universal cycle. It started on August 11, 3114 BC, the day the Mayans believed mankind was created and ended on December 21, 2012 with the universe destroyed and recreated. The mystery lies not in why the world did not end but how were they so precise to calculate the end to be exactly on the winter solstice.

The Mayans did not have complex instruments for charting the position of celestial objects; their observations were with the naked eye. They may have had rudimentary instruments such as crossed sticks but not instruments such as sextants. Although they did use their buildings as instruments, they aligned the temples to help observers monitor the position of celestial objects, like the Sun or Venus. Two of the corners pointed in the direction of the Sun (one pointed towards the Sun as it rose, the other as it set) so that on the Spring and Autumn equinox, at the rising and setting of the Sun, the corners of the structure casts a shadow in the shape of a plumed serpent or Quetzalcoatl along the west side of the north staircase. On these two annual occasions, the shadows from the corner tiers slither down the northern side of the pyramid with the Sun's movement to the serpent's head at the base.

Still the question arises: how did the Mayans do it? We still do not know exactly the answer to this question but it is truly amazing that they were able to do things like create extremely precise calendars, calculate the solstices and equinoxes, and calculate when the Earth and Mercury are aligned hundreds of years in advance.

- José Uribe