The Birth of Cells

Life has existed on Earth for more than 4 billion years, yet the precise origin of the first cells remains a mystery. Our understanding of what Earth was like when this occurred has allowed us to develop a few theories regarding the birth of cells. Firstly, most of the surface of the planet was covered in water. Moreover, the atmosphere did not have molecular oxygen or an ozone layer. As such, the surface of the Earth was exposed to considerably more UV radiation from the sun. Given these conditions on the planet, our best guess of where simple single-cellular life may have first flourished is somewhere in oceanic depths near hydrothermal vents, or beneath the surface of the Earth. There are specific requirements that had to be fulfilled for cells to have arisen—structures that permitted molecules to come together to form a cell. In particular, hereditary material such as DNA and RNA, and a structure for compartmentalization such as a cell wall or membrane, were needed. The formation of these structures is the result of prebiotic chemical and physical processes.The RNA world hypothesis is a widely accepted theory that suggests that self-replicating ribonucleic acid molecules are the precursors to prokaryotic cells. Over time, RNA developed enzymes allowing it create polymers of amino acids, eventually leading to the more stable DNA. In the first cells, however, it is believed that a more primitive version of RNA acted as the hereditary material.

Fatty acids in water, given a level above a threshold concentration, spontaneously form a bilayer, a physically stable, low-energy configuration. This bilayer takes on a spherical shape. As such, this create a structure that envelopes water within its walls, a sort of vesicle. Again, this occurs as a direct result of the tendency of matter to organize itself into its most stable state. Supplying the vesicle with more fatty acids (in the form of organic compounds and the energy needed for the formation of said fatty acids) allows it to grow and divide. When the size of the bilayer increases by a fixed amount, its volume increases more than its surface area. And if the contents within the vesicle are not changed, the bilayer will naturally cave around its equator, resulting in a dumbbell-shaped vesicle, a first step towards cell division. Furthermore, hereditary material can become embedded in phospholipid bilayers, and with energy from hydrothermal vents, it is possible that this union of the two structures led to the first cell. Lastly, RNA within the cell, capable of replicating, would also split into both parts of the vesicle when a the bilayer begins to divide. This results in a cell with a membrane, hereditary material, and the ability to reproduce. The bilayer composed of fatty acids and the hereditary material are some of the most important structures needed for simple single-cellular life to have developed.

Sources:

Lane, Nick. The Vital Question: Energy, Evolution, and the Origins of Complex Life. New York: W.W. Norton, 2015. Print.

- Ricardo Roche

The Possibilities of Time Travel

Time travel is a phenomenon that has been fascinating the human race for centuries. Since the development of Einstein’s theory of relativity, physicians have especially shown a special interest in this field. Einstein’s special theory of relativity suggests that time passes at different rates to different observers. This development resulted from the discovery that traveling at the speed of light would make time appear slower than to an individual with a lower speed. This breakthrough provided unprecedented insight into the nature of space and time and its interactions with gravity. As a result, scientists found that matter is actually able to distort space such that the rate of time is adjusted. They expected this distortion, now referred to as a “wormhole”, to be shaped like a tunnel with two entrances so that inside, time is stopped.

Since the first mention of wormholes, the scientific community has been investigating whether they actually exist and the implications they may hold. Since wormholes act as passages through space-time, they may potentially create shortcuts for journeys across the universe. Scientist Robert Oppenheimer theorized that a star collapse might give way to a wormhole by leaving a black hole that would warp space into a wormhole. However, these Schwarzschild black holes are found to retain charge and spin, which would require one to travel at a speed greater than that of light. Instead, simpler types of black holes would be more ideal to act as passageways and time machines as they allow for speeds slower than the speed of light.

With more research on the feasibility of time travel, physicists have also looked into the implications of time travel for human life. The most well known conflict they face is the grandfather paradox: can time travelers actually change history? This had led the way to a variety of “what-if” scenarios such as killing a family member or meeting oneself, which also caused wide scale discussion on their potential consequences. A large problem that arises is causality, which refers to when an event occurs only after a driving force. This principle may be violated through time travel into the past if one were to interfere with history.

The discussion on time travel and human interference has given way to multiple models of the events that would unfold after changing the past. One model of time travel by researcher Seth Lloyd suggests that paradoxical events would actually be censored by making unlikely events to happen more frequently. For example, in the grandfather’s death instance, a bullet that was used to kill a time traveler’s grandfather would be more likely to be defective so that he couldn’t be killed. Another model by David Deutsch allows inconsistencies between a time travel’s memories and their actual experiences so that he would remember killing his grandfather without having done it.

Unfortunately, we cannot know the true nature of time travel until humans are able to pass through spacetime differently. As a result, physicists have been further looking into the feasibility of time travel via wormholes. There is no clear answer currently to whether humans are capable of travelling through, developing, or stabilizing a wormhole. However, with the rapid developments of science and technology, we will hopefully gain a much greater understanding of space and time travel that may pay off thousands of years from now.

Sources:

“Time Travel: Tunnels Through Time” by Barry Parker (1992)

“Time travel gets more plausible, yet weirder too” by Laura Sanders (2016)

- Shreya Punya

Positive Considerations for the Colonization of Mars

Besides being a potential candidate for terraformation, Mars is seen as a beacon of hope for the future of humanity by proponents of colonization. They are in turn challenged by dissidents who bring up ethical and practical issues of taking on such an operation. These issues included our right as a species to endanger another by corrupting their natural environment, and the impracticality and costs of terraformation. The atmosphere, water content, gases, etc., of Mars render the process of maintaining an Earth-like environment difficult and costly in the long run.

Proponents of colonization uphold many reasons for the settlement of Mars. But in particular, the strongest motive is the preservation of the human race. Since WWII, the scale of nuclear weapons have greatly increased, and technology has advanced immensely. Although we have been able to maintain some stability on Earth, it seems that while we move further ahead into the future, these developments will only create more social or economic issues. Proponents of colonization believe that an international effort to settle Mars will bring humanity together in a collective effort to survive, or an “alternative to destructive wars that could decimate high tech civilization on Earth and humanity’s chance to reach the stars”(Paine). The additional fact that material from nuclear warheads around the globe can be used as fuel for future Martian civilizations for a long time, is another incentive for colonization. An international collective effort to use these weapons for this purpose would simultaneously bring us together for the common purpose of futhering humanity in colonizing a new world, as well as lessening the possibility of using these weapons for their original purpose. Basically, the goal of colonizing mars is both unifying and possibly beneficial in some perspectives. Settlement of Mars would also imply other benefits for humanity such as economic development and growth through expansion of our economy throughout the solar system and resources to be discovered, as well as a clean slate for humanity to restart itself.

In addition, Mars shows some promise in maintaining a good economic balance, in terms of what it can provide for Mars-Earth trade. For example, steel- an important industrial material, can be retrieved from mars in iron form in many quantities. Compared to steel production on Earth, that on Mars is significantly easier, since the conditions are so that the energy intensive reduction process is not necessary(Landis). In return, Mars’ arid soil would need to be fertilized through Earth’s resources, further enhancing the trade system in the process of colonization. Despite the numerous questions and ethical issues raised by dissidents of the colonization/ terraformation of Mars, it seems that fostering a civilization on this planet is in fact an achievable and potentially very beneficial project. Mars possesses most of the raw materials required to uphold a civilization and build what is required to sustain it. The only issue besides that would be of the moral implications, if it is discovered that microbes/life on Mars is confirmed to exist.

Sources:

http://www.aleph.se/Trans/Tech/Space/mars.html

http://go.galegroup.com/ps/retrieve.do?sort=RELEVANCE&docType=Article&tabID=T002&prodId=AONE&searchId=R1&resultListType=RESULT_LIST&searchType=AdvancedSearchForm&contentSegment=&currentPosition=1&searchResultsType=SingleTab&inPS=true&userGroupName=cmu_main&docId=GALE%7CA13330278&contentSet=GALE%7CA13330278
http://vufind.library.cmu.edu/vufind/Summon/Record?id=FETCH-crossref_primary_10_1111_j_1472_4669_2010_00254_x3

http://www.sciencedirect.com/science/article/pii/S009457650800266X

- Haeun Bang

The Implications of Living in a Simulation

If we are in fact part of a simulation then we have an answer to our existence and several possible solutions to alien existence. We know where we came from: our existence is due to a civilization that reached a point where they could create a simulation of the Universe, and did so. Thus our existence is as part of a program rather than within a Universe that arose by natural means. In this regard we don’t really exist on our own: entities that exist outside of our Universe control our destiny. On a side note, being in a simulation would also explain the Big Bang: the program began with the Big Bang, or at some point later with observational evidence of the Big Bang coded into it. Being in a simulation answers many questions that we have about the Universe, but also has many implications for the way we live in the future. If we discover that our world is a simulation there are several elements of everyday life that will change.

First, our living in a simulation means that we do not exist in the traditional sense. Living in a traditional sense implies you exist, everyone else exists, and the Universe exists as well. In example, if the Universe is a hologram then we would perceive ourselves to be living normally, while in fact the world is not what we perceive it to be. Many people may have existential crisis, since being told you are in a simulation can be quite a shock. However, the simulation world will still follow the rules of the Universe we. This means that the laws that govern our society are not changed. If we discover we are in a simulation, gravity will not cease to exist. Just because we found out we are in a simulation does not mean that the laws of nature have changed.

Possibly the largest implication would be the effect this knowledge would have on religion. Most religions are based around either a single god or a group of gods that created the world or have some on-going impact on our everyday lives. If we discover that the Universe was made by some higher-order beings than there are two ways the religious can respond: either they shift their identification of god to those that made the simulation or they can denounce their religion. There is a third option, ignorance, which some may choose but does not need explanation as to the change involved. There will always be people that will not believe the evidence brought forth if we are found to be part of a simulation.

If religions reimagine their god(s) to be the creator(s) of the simulation, they will have undeniable proof that god exists (assuming we have undeniable proof of being in a simulation, which I know to be difficult to explain). If every religion updates their definition of god then every religion will end up praying to the same creators. Perhaps one religion will emerge from the chaos that would ensue, a hybrid religion that combines what we currently believe with what we have learned from being in a simulation. However if religions cannot adapt their definitions of god then they will struggle while trying to maintain their previous assumptions. Finding proof that we live in a simulation will result in huge changes to society, for better or worse.

- Adin Adler

Directed Panspermia

The panspermia hypothesis states that life is found throughout space, carried from planet to planet by meteors or other objects. There is a multitude of variations on this idea ­ some argue that hardy microorganisms undertake not just interplanetary journeys but interstellar ones as well; others find the idea of alien microbes too far­fetched, and maintain that panspermia takes place with organic molecules only. Some even claim that panspermia is deliberately initiated by intelligent life: a hypothesis specifically referred to as directed panspermia, where the biological spores in question are intentionally dispersed by intelligent civilizations, using natural or artificial means.

Most speculation about directed panspermia falls under two umbrella questions: Could an intelligent species seed an Earthlike planet with life? And could humans do the same with a clear conscience?

If panspermia occurs naturally, as many argue that it does, then panspermia aided by technology should be that much more effective, and thus that much more common. After all, if alien bacteria can make interplanetary journeys on their own, then they can certainly do it with help ­ yet no evidence of directed panspermia has ever been discovered. Opponents of panspermia (or at least those who maintain a belief in extraterrestrial intelligence) claim that by simple contraposition, this lack of proof proves that panspermia “doesn’t work.” However, due to the (apparent) scarcity of technologically advanced societies in our sector of space, an absence of evidence for directed panspermia does not necessarily mean that it is impossible ­ only that no nearby alien civilizations are putting it into practice.

The intentional propagation of microbial life throughout space does indeed seem to be possible. In science fiction directed panspermia is usually the work of a species far more advanced than ours, but the reality is that panspermia could likely be initiated using today’s human technology. Capsules on the order of a few millimeters or centimeters could conceivably carry Earth bacteria to other star systems using an efficient solar sail propulsion system. They might take hundreds of thousands of years to arrive at their destination, and many would perish on the journey, but the process is definitely within reach.

Human­-initiated panspermia is, of course, a highly controversial proposal, with strong feelings on both sides. On one hand, the most popular argument in favor of the colonization of other planets is to have a “backup” in case of disaster on Earth: so as a means of making a planet habitable for human life, directed panspermia might be a simpler and far cheaper alternative to terraformation (albeit a far more gradual one). On the other hand, propagating Earth life elsewhere in the galaxy could annihilate existing biospheres, in the same way that an invasive plant species can drive a native one to extinction. Though we do have the technology to disperse life, we aren’t capable of detecting it from afar, meaning that any panspermia campaign could have this effect. Even in the far future, with hypothetical technology capable of detecting evidence of microbes on planets lightyears away, this could prove an ethical problem. Humans could confirm the absence of life on a planet and send biological capsules its way; but there is no guarantee that life would not evolve during the long interval between the capsule’s launch and its arrival. To sidestep this problem, some have suggested targeting newborn stellar systems, where life would not have time to evolve.

The problem with directed panspermia is that almost all of the factors that would help us through this ethical dilemma are unknown. Nobody knows for certain how life originates, or how often, or where (let alone why) . Though human tendency in similar situations has historically been to “go ahead and do it anyway,” in this case the morally minded can breathe a sigh of relief: the technology exists, but the monetary cost of launching a fleet of biological capsules is still prohibitively high for those who would like to do so.

Sources:

Gilster, Paul, “Seeding the Galaxy” -- http://www.centauri­-dreams.org/?p=11334

Makukov and shCherbak, “Space Ethics to Test Directed Panspermia,” Life Sciences in Space Research, July 2014

The Interstellar Panspermia Society, “Principles of Panbiotic Ethics”-- http://www.panspermia­society.com/ethics.php

- Emma Flickinger

Alien Appearance

Assuming that aliens do exist somewhere in the universe, how will we compare to them physically? Fergus Simpson, a cosmologist, performed a Bayesian analysis regarding the size of aliens, size of planets, and population sizes. After considering these factors, Simpson holds the belief that we should not be looking at Earth-like planets because our planet is not representative of inhabitable planets as a whole. Instead, we should be looking at planets of smaller size.

According to Simpson, we may make predictions about alien life based on our current Earth. For our purpose, we are naming an individual country as a “group” of people. If we take a look at the number of countries and their population sizes, we notice that more than 50% of humans live in seven countries. Because of this fact, the median person will probably be a member of one of these seven countries. However, the majority of countries have populations less than six million. If we were to take the median country based on population size, the chosen country would not be from one of the seven largest countries. Anytime groups are of different sizes, most individuals will be members of groups of larger size.

However, when it comes to figuring out where we are in comparison to other life forms, we cannot say with 100% confidence which part of the spectrum we are on. All things being equal, a randomly selected person is most likely to be a member of a more populous group, whether we group by race or blood type or by nationality. Whether it involves blood type or race, we are not equally likely to belong in each group. Simpson takes uses this fact and applies it to our planet so as to compare it to all the “other” planets that house alien life. He proceeds to make the assumption that we are a part of a large group.

Countries with high populations tend to have larger land areas. Because Simpson makes the assumption that we are on the higher end of the population size spectrum, he concludes that our planet is also on the higher end of the size spectrum. If we may compare planets like we compare countries, then there is a higher number of smaller-sized planets. Therefore, we should be looking at smaller planets instead of Earth-sized planets, as there are simply a larger number of inhabited smaller-than-Earth-sized planets than Earth-sized planets or larger.

Apart from population size, we may also hypothesize the size of these aliens. If we take a look at common species on Earth, smaller creatures tend to have a higher population size than larger creatures. For example, the population size of smaller ones like an ant is much larger than the population size of a larger ones like a hippopotamus. We may then apply this concept to the sizes of aliens in comparison to human beings. Above, we saw that we may assume that there are more smaller-than-Earth-sized planets. Given this assumption, these planets also have smaller population sizes, so their inhabitants are likely to have a larger physical sizes. So, it is probable that we are smaller in comparison to most alien populations.

Source:

http://www.thebigalientheory.com/

- Stephanie Bao

The Murchison Meteorite and the Origin of Life

How did the first living being arise on Earth? A number of answers have been proposed to this question – yet no theory has been accepted as fact. Current scientific research suggests that the answer lies on our very own planet – albeit contained on an asteroid that originated far from Earth. The Murchison Meteorite, an object of great significance in the field of astrobiology, landed on Earth on September 28, 1969 near the quiet Australian town of Murchison at approximately 10:45 AM.¹ Fragments from what later became known as the meteor scattered across the countryside – each containing evidence that would become crucial to astro-biological research.

A large fragment of the Meteorite.²

Closer examination of the meteorite fragments revealed an abundance of both right-handed and left-handed amino acids and evidence of nucleobases that are comprise both DNA and RNA.³ Nucleobases are defined to be “structures that play fundamental roles in in carrying genetic information of all living things.”⁴ To illustrate the importance of such a discovery, take DNA and RNA to be a computer. Nucleobases are then metaphorically thought of as the various components of the computer, such as the hard drive. While a hard drive is essential for the operation of the computer; a hard drive itself does not constitute a computer. Similarly, a nucleobase does not constitute DNA or RNA by itself, but it essential to their function. One must note that “samples were gathered soon after impact”,⁴ therefore it is reasonable to assume that the samples were not contaminated – meaning that all compounds on the meteorite were of extraterrestrial origin.

The discovery of right-handed amino acids and nucleobases on the Murchison meteorite may provide the missing link in determining the ultimate origin of life.⁵ While the Miller-Urey Experiment concluded that organic molecules, namely amino acids, can arise naturally on Earth, they were unable to create life from such compounds. The compounds created are necessary for life to develop, alone they are not sufficient for life to develop. Some combination of the extraterrestrial materials found on the Murchison Meteorite may provide the missing component necessary for life to arise.

For some scientists, the discovery of nucleobases led them to speculate that life on Earth arose from an extraterrestrial source.⁶ Scientists who subscribe to a theory about the origin of life known as Panspermia, a theory stating that life on Earth did not originate on it, continue to debate exactly how life was transferred to Earth.⁷ Most scientists advocating for the Panspermia theory agree that meteors like the Murchison Meteorite act as the vehicles for such a transmission.⁸ After an impact had occurred, the materials from a meteor would react with the materials present on Earth to create life. While this model seemingly makes sense, a fatal flaw is present. The model – as it is currently stated – assumes that the materials that may be present on an asteroid can survive an impact. Assuming that organic compounds and organisms capable of surviving such an impact exists – such materials could exist in most places in the Universe.⁹ The idea of hardy organisms capable of surviving implying widespread life throughout the Universe characterizes the so-called “Panspermia Paradox,” as dubbed by sources such as RealClearScience¹⁰ and Scientific American.¹¹ Organic compounds and organisms honed by natural selection to survive in space for extended periods of time should be common throughout the Universe, spread by asteroids and comets – but such organisms have yet to be observed.

The findings on the Murchison Meteorite serve to clarify the paradox known as the “Panspermia Paradox.” The presence of nucleobases and both left and right handed amino acids confirms the longevity of certain organic compounds.¹² The findings of the Murchison Meteorite necessitate a re-examination of current efforts to search for extraterrestrial life. Other asteroids must be collected and planets must be explored. If such molecules could survive on an asteroid – they are most likely present on other planets.

Sources:

¹http://www.pbs.org/exploringspace/meteorites/murchison/page6.html
²http://sciencelearn.org.nz/var/sciencelearn/storage/images/contexts/satellites/sci-media/video/murchison-meteorite-an-early-glimpse-inside-a-comet/1262248-1-eng-NZ/Murchison-meteorite-an-early-glimpse-inside-a-comet.jpg
³https://briankoberlein.com/2015/04/07/it-came-from-outer-space/
⁴http://www.astrochem.org/sci/Nucleobases.php
⁵http://discovermagazine.com/2009/jan/050
⁶http://www.scientificamerican.com/article/were-meteorites-the-origi/
⁷https://helix.northwestern.edu/article/origin-life-panspermia-theory
⁸http://www.space.com/22880-life-from-space-panspermia-possibility.html
⁹http://blogs.scientificamerican.com/life-unbounded/the-panspermia-paradox/
¹⁰http://www.realclearscience.com/2012/10/16/panspermia_paradox_where039s_all_the_life_249540.html
¹¹http://blogs.scientificamerican.com/life-unbounded/the-panspermia-paradox/
¹²http://www.nasa.gov/centers/goddard/news/topstory/2009/left_hand_life.html

- Frank Kovacs