<p><div class="KonaFilter image-container display-table float_right"><div><div class="image on-image"><p class="source"><span>©Alan Friedman/ avertedimagination.com</span></p></div><p></p></div></div>How do you go about hunting for life on <a href="https://theconversation.com/au/topics/exoplanets">another planet</a> elsewhere in our galaxy? A useful starting point is to imagine looking from afar for signs of life on Earth.</p><p>In a telescope like those we have on Earth, those aliens would likely just see the Earth and sun merged together into a single pale yellow dot.</p><p>If they were able to separate the Earth from the sun, they'd still only see a pale blue dot.</p><p>There would be no way for them to image our planet's surface and see life roving upon it.</p><p>However, those aliens could use <a href="http://loke.as.arizona.edu/~ckulesa/camp/spectroscopy_intro.html">spectroscopy</a>, taking Earth's light and breaking it into its component colours, to figure out what gases make up our atmosphere. Among these gases, they might hope to find a "biomarker", something unusual and unexpected that could only be explained by the presence of life.</p><p>On Earth, the most obvious clue to the presence of life is the abundance of free oxygen in our atmosphere. Why oxygen? Because it is highly reactive and readily combines with other molecules on Earth's surface and in our oceans. Without the constant resupply coming from life, the free oxygen in the atmosphere would largely disappear.</p><h2>Biomarkers</h2><p>But the story isn't quite that simple. Life has existed on Earth for <a href="https://theconversation.com/no-australias-new-fossils-are-not-the-oldest-but-their-value-is-set-in-stone-2994">at least 3.5 billion years</a>. For much of that time, however, oxygen levels were far lower than those seen today.</p><p>And oxygen alone is not enough to indicate life; there are many abiological processes that can contribute oxygen to a planet's atmosphere.</p><p><div class="KonaFilter image-container display-table"><div><div class="image on-image"><p class="source"><span>Wikimedia</span></p><p class="caption">The concentration of oxygen in the Earth's atmosphere over the last billion years. As a reference, the dashed red line shows the present concentration of 21%.</p></div><p></p></div></div></p><p>For example, ultraviolet light could produce abundant oxygen in the atmosphere of a world covered with water, even if it was devoid of life.</p><p>The upshot of this is that a single gas does not a biomarker make. Instead, we must instead look for evidence of a chemical imbalance in a planet's atmosphere, something that can not be explained by anything other than the presence of life.</p><p>Here on Earth, we have one: our atmosphere is not just rich in oxygen, but also contains significant traces of methane. While abundant oxygen or methane could easily be explained on a planet without life, we also know that methane and oxygen react with each other strongly and rapidly.</p><p>When you put them together, that reaction will cleanse the atmosphere of whichever is least common. So to maintain the amount of methane in our oxygen-rich atmosphere, you need a huge source of methane, replenishing it against oxygen's depleting influence. The most likely explanation is life.</p><h2>Observing exoplanetary atmospheres</h2><p>If we find an exoplanet sufficiently similar to our own, there are several ways in which we could study its atmosphere to search for biomarkers.</p><p>When a planet passes directly between us and its host star, a small fraction of the star's light will pass through the planet's atmosphere on its way to Earth. If we could zoom in far enough, we would actually see the planet's atmosphere as a translucent ring surrounding the dark spot that marks the body of the planet.</p><p>How much starlight passes through that ring gives us an indication of the atmosphere's density and composition. What we get is a "<a href="https://theconversation.com/explainer-seeing-the-universe-through-spectroscopic-eyes-37759">transmission spectrum</a>", which is an absorption spectrum of the planetary atmosphere, illuminated by the background light of the star.</p><p>Our technology has only now become capable of collecting and analysing these spectra for the first time. As a result, our interpretation remains strongly limited by our telescopic capabilities and our burgeoning understanding of planetary atmospheres.</p><p>Despite the current challenges, the technique continues to develop with great success. In the past few years, astronomers have discovered a wide variety of different chemical species in the atmospheres of some of the biggest and baddest of the known transiting exoplanets.</p><p><div class="KonaFilter image-container display-table"><div><div class="image on-image"><p class="source"><span>NASA/JPL-Caltech</span></p><p class="caption">Many exoplanets may have no atmosphere at all.</p></div><p></p></div></div></p><h2>Eclipses</h2><p>Another approach involves observing a transiting planet and its star as they orbit one another. The goal here is to collect some observations when the planet is visible (but not in transit), and others when it is eclipsed by its star.</p><p>With some effort, astronomers can subtract one observation from the other, effectively cancelling the hugely dominant contribution of light from the star. Once that light is removed, what we have left is the day-side spectrum of the planet.</p><p><div class="KonaFilter image-container display-table"><div><div class="image on-image"><p class="source"><span>NASA/JPL-Caltech/R. Hurt (SSC/Caltech)</span></p><p class="caption">Star + Planet] - [Star] = [Planet]</p></div><p></p></div></div></p><h2>The future</h2><p>Astronomers are constantly developing new techniques to glean information about exoplanetary atmospheres. One that shows particular potential, especially for the search for planets like our own, is the use of <a href="http://web.gps.caltech.edu/~vijay/Papers/Polarisation/Planetary%20Atmospheres/bailey-07.pdf">polarised light</a>.</p><p>Most of the light we receive from planets is reflected, originating with the host star. The process of reflection brings with it a subtle benefit - the reflected light gains a degree of polarisation. Different surfaces yield different levels of polarisation, and that polarisation might just hold the key to finding the first oceans beyond the solar system.</p><p><div class="KonaFilter image-container display-table"><div><div class="image on-image"><p class="source"><span>Wikimedia, CC BY-SA</span></p><p class="caption">By rotating a polarising filter, we can block light of certain polarisation. This is how polarised sunglasses cut the glare from puddles and the ocean on a sunny day.</p></div><p></p></div></div></p><p>These methods are still severely constrained by two factors: the relative faintness of the exoplanets, and their proximity to their host star. The ongoing story of exoplanetary science is therefore heavily focused on overcoming these observational challenges.</p><p>Further down the line, advances in technology and the next generation of telescopes may allow the light from an Earth-like planet to be seen directly. At that point, the task becomes (slightly) easier, in part because the planet can be observed for far longer, rather than just relying on eclipse/transit observations.</p><p>But even then, spectroscopy will be the way to go; the planets will still be just pale blue dots.</p><h2>What we have seen so far</h2><p>The exoplanets we have discovered to date are highly inhospitable to life as we know it. None of the planets studied so far would even be habitable to the most extreme of <a href="http://oceanservice.noaa.gov/facts/extremophile.html">extremophiles</a>.</p><p>The planets whose atmospheres we have studied are primarily "hot Jupiters", giant planets orbiting perilously close to their host stars. As they skim their host's surface, they whizz around with periods of just a few days, yielding transits and eclipses with every orbit.</p><p>Because of the vast amounts of energy they receive from their hosts, many of these "hot Jupiters" are enormous, inflated far beyond the scale of our solar system's largest planet. That size, that heat and their speed, make them the easiest targets for our observations.</p><p>But as our technology has improved, it has also become possible to observe, through painstaking effort, some smaller planets, known as "super-Earths".</p><h2>Atmospheres of distant planets…</h2><p>The hot Jupiter <a href="http://exoplanet.eu/catalog/hd_189733_b/">HD189733</a> has one of the best understood planetary atmospheres beyond the solar system.</p><p><div class="KonaFilter image-container display-table"><div><div class="image on-image"><p class="source"><span>NASA, ESA, M. Kornmesser</span></p><p class="caption">Artists impression of the broiling blue marble, HD 189733 b.</p></div><p></p></div></div>Observations by the Hubble Space Telescope, in 2013, suggest a deep-blue world, with a thick atmosphere of silicate vapour. Other studies have shown its atmosphere to contain significant amounts of water vapour, and carbon dioxide.</p><p>Overall, however, it appears to be a hydrogen-rich gas giant like Jupiter, albeit super-heated, with cloud tops exceeding 1,000 degrees. Beneath the cloud turps lies a widespread dust layer, featuring silicate and metallic salt compounds.</p><p>The young giant planets in the <a href="http://www.space.com/20231-giant-exoplanets-hr-8799-atmosphere-infographic.html">HR8799</a> system appear to have hydrogen-rich but complex atmospheres, with compounds such as methane, carbon monoxide and water. They are likely larger, younger, and hotter versions of our own giant planets - with their own unique subtleties.</p><p><div class="KonaFilter image-container display-table"><div><div class="image on-image"><p class="source"><span>Ben Zuckerman</span></p><p class="caption">A direct image of the four planets known to orbit the star HR 8799.</p></div><p></p></div></div>For the super-Earth <a href="http://www.space.com/14634-alien-planet-steamy-waterworld-gj1214b.html">GJ1214b</a> the lesson is to be careful about making conclusions. Early suggestions that this might be a "water world" or have a cloudless hydrogen atmosphere have since been superseded by models featuring a haze of hydrocarbon compounds (like on <a href="http://www.nasa.gov/mission_pages/cassini/whycassini/cassini20130605_prt.htm">Titan</a>), or grains of potassium salt or zinc sulphide.</p><p>While the search for Earth-like planets continues using ground- and space-based telescopes, exoplanetary scientists are eagerly awaiting the launch of the James Webb Space Telescope <a href="https://theconversation.com/au/topics/james-webb-telescope">JWST</a>.</p><p>That immense telescope, scheduled for launch in around October 2018, could mark the true beginning of the exciting search for distant atmospheric biomarkers and exoplanetary life.</p><p><em>Brad Carter, Amanda Bauer and Jonti Horner contributed to this post for The Conversation.</em></p><p></p>    <div class="margin-top">        <h3>NOW WATCH: <a href="http://www.businessinsider.com/what-like-eat-food-grown-space-nasa-2015-11">This is what it's like to eat food grown in a 'space garden'</a></h3>        <div>            <div>        <div class="ooyala-video-player" data-video-autoplay="false" data-video-id="l5eWh2eDrtdBaSYSf1RiuC1DKIbTcscZ" data-player-variable="ooyalapopvideo" id="ooyalaplayer_popvideo" style="width:1280px;height:720px"></div>        </div>        </div>            </div>

Here's how to search for alien life on distant planets

<p><div class="KonaFilter image-container display-table float_right"><div><div class="image on-image"></div><p></p></div></div>Superfast computers built on the bizarre principles of quantum physics are coming, and when they finally get here, they're going to change everything.</p><p>Eric Ladizinsky, cofounder of the quantum computing company D-Wave, gave a great explanation of the difference between a regular computer and a quantum computer during a <a href="https://www.youtube.com/watch?v=bLJ38KDS4Pc" target="_parent">talk at the WIRED 2014 conference</a> in London.</p><p>Imagine you only have five minutes to find an "X" written on a page of a book in the Library of Congress (which has 50 million books). It would be impossible. But if you were in 50 million parallel realities, and in each reality you could look through the pages of a different book, in one of those realities you would find the "X."</p><p>In this scenario a regular computer is you running around like a crazy person trying to look through as many books as possible in five minutes. A quantum computer is you split into 50 million yous, casually flipping through one book in each reality.</p><p>If this still sounds like magic or witchcraft, you're not alone. Physicist Richard Feynman once famously said: "If you think you understand quantum physics, you don't understand quantum physics."</p><p>The bottom line is that regular computers have to solve one problem at a time in sequence, but quantum computers can solve multiple problems at the same time. That kind of speed as the potential to revolutionize entire industries.</p><p>And it's not just their speed. Quantum computers can solve the kind of complex problems that regular computers are really bad at solving. They're more human-like in their problem solving approach, and that will make them better able to complement human tasks.</p><p>We definitely still have <a href="http://www.businessinsider.com/googles-quantum-computing-milestone-2015-3" target="_parent">more tech issues</a> to work out before we have fully-functioning quantum computers, but here are some of the most exciting future applications of quantum computing:</p><h3><strong>1. Really accurate weather forecasting <br /></strong></h3><p>Even with cutting edge instruments that analyze temperature and pressure, there's too many possible ways a given weather pattern can manifest itself, and current weather forecasting is an educated guess at best, Ray Johnson, a board member at the startup quantum computing company <a href="http://www.qxbranch.com/" target="_parent">QxBranch</a>, told Business Insider.</p><p>Quantum computing could analyze all that data at once and give us a better idea of when and where bad weather will strike. We'd have advanced notice of major storms like hurricanes and the extra prep time could help save lives.</p><p><div class="KonaFilter image-container display-table full"><div><div class="image on-image"></div><p></p></div></div>Director of engineering at Google, Hartmut Neven, also noted <a href="http://googleresearch.blogspot.ca/2013/05/launching-quantum-artificial.html" target="_parent">wrote</a> that quantum computers could help build better climate models that could give us more insight into how humans are influencing the environment. These models are what we build our estimates of future warming on, and help us determine what steps need to be taken now to prevent disasters. Knowing more about how our climate scenario will play out can only help us in the long run.</p><h3><strong>2. More efficient drug</strong><strong> discovery</strong></h3><p><div class="KonaFilter image-container display-table float_right"><div><div class="image on-image"></div><p></p></div></div>Developing a new drug is a complicated process.</p><p>Chemists have to test tons of different molecular combinations to find one that actually has properties that are effective against a disease. This process can take years and cost millions of dollars. Chemists bring tons of these combinations to later-stage trials and many of them still end up failing.</p><p><strong>A quantum computer would be able to map out trillions of molecular combinations and quickly identify the ones that would most likely work, significantly cutting down the cost and the time of drug development.</strong></p><p>Quantum computing could also <a href="https://books.google.com/books?hl=en&amp;lr=&amp;id=L6N_BAAAQBAJ&amp;oi=fnd&amp;pg=PA92&amp;dq=quantum+computing+drug+development&amp;ots=p1zB7UDX1E&amp;sig=VEPZ6MLrOBy3frlzhwuu2Nc-PGA#v=onepage&amp;q&amp;f=false" target="_parent">sequence and analyze a person's genes much faster</a> than the methods we have now, and that could also help make personalized drugs and healthcare more available to the masses.</p><p>Right now, many drugs don't make it to market because, for example, a small subset of people react particularly badly to it. So we usually kill that drug even though it might be helpful for some people. With personalized gene analysis and better drug knowledge we could predict these bad interactions.</p><h3><strong>3. No more traffic nightmares</strong></h3><p><div class="KonaFilter image-container display-table float_right"><div><div class="image on-image"></div><p></p></div></div>Quantum computing could streamline both air traffic and ground-based traffic control because they're so good at quickly calculating the optimal route.</p><p>If you're planning a road trip with 10 different stops, a regular computer would have to individually calculate the length of all the possible routes you could take and then figure out the best one. A quantum computer could calculate the length of all the routes at the same time and arrive at the optimal route much faster - these are the exact kinds of calculations needed for directing airplanes or analyzing traffic.</p><p>Sophisticated analysis of air traffic patterns using a quantum computer would mean <a href="http://www.nas.nasa.gov/quantum/quantumcomp.html" target="_parent">more efficient flight scheduling</a> and would cut down on travel time since we could better avoid bottle-necking in airport take offs and landings.</p><p>The same technique could be applied to highways and complicated city grids to avoid congestion.</p><h3><strong>4. Beefing up military and defense</strong></h3><p>Satellites are constantly collecting tons of images and video. There's far more data than anyone could ever search through, so a lot of it just gets tossed aside, Johnson said. We might miss crucial intelligence in some of that discarded data.</p><p>A quantum computer would sort through that mountain of data much faster than a regular computer or a human could, and it could point us to which images and videos we should take a closer look at and which ones we can just ignore and throw out.</p><p>Regular computers aren't very good at this "Where's Waldo?" kind of recognition, but, like humans, quantum computers are really good at picking out specific details from a messy background.</p><h3><strong>5. Secure, encrypted communication</strong></h3><p>We use encryption all the time whether we realize it or not. We rely on it when we sign into an email account or use our credit card to buy something online.</p><p>It's possible to make encryption even more secure by using the same weird quantum mechanics property that makes a quantum computer work.</p><p>This ultra-secure communication is called <a href="http://www.businessinsider.com/what-is-quantum-encryption-2014-3" target="_parent">quantum key distribution</a> and it allows someone to send a message to someone else that only they can read by using a key to decipher it. If a third party intercepts the key then, thanks to the weird magic of quantum mechanics, it becomes useless and no one can read the message. A preliminary version of this kind of communication technology is used by a few places in Europe, but it's still largely unavailable in the US.</p><p><div class="KonaFilter image-container display-table float_right"><div><div class="image on-image"></div><p></p></div></div>But while the same principle of quantum computing could make communication more secure, quantum computers could make it much much easier to <a href="http://motherboard.vice.com/read/your-encryption-will-be-useless-against-hackers-with-quantum-computers" target="_parent">break the encrypted messages</a> that we have now. Some of Edward Snowden's <a href="http://www.washingtonpost.com/world/national-security/nsa-seeks-to-build-quantum-computer-that-could-crack-most-types-of-encryption/2014/01/02/8fff297e-7195-11e3-8def-a33011492df2_story.html" target="_parent">leaked documents</a> from the NSA describe the agency's plan to develop quantum computers to do just that.</p><p>If a hacker (or nosy government) ever got their hands on a working quantum computer, more old-school encrypted data from places like banks and governments could be in serious danger.</p><h3><strong>6. Accelerating space exploration</strong></h3><p>Astronomers have discovered nearly 2,000 confirmed planets outside our solar system using the <a href="http://exoplanetarchive.ipac.caltech.edu/" target="_parent">Kepler space telescope</a>.</p><p>The Kepler search involves peering at these distant so-called exoplanets and waiting for them to pass in front of their host star. When that happens, the exoplanets cast a shadow that astronomers can then analyze and make predictions about whether their atmosphere is suitable for life or not.</p><p><div class="KonaFilter image-container display-table full"><div><div class="image on-image"></div><p></p></div></div>A <a href="http://www.nas.nasa.gov/quantum/research.html" target="_parent">quantum computer could tackle more data</a> in any given telescope view, spot more exoplanets, and help quickly identify which ones have the most potential to harbor life. It could even uncover exoplanets that Kepler missed during its first run through older images.</p><h3><strong>7. Machine learning and automation</strong></h3><p>It sounds super creepy, but like humans, quantum computers can learn from experience. They can self correct. For example, a quantum computer could actually modify the code of a program that keeps messing up.</p><p>This concept is called machine learning - it's similar to how your Facebook news feed changes based on which posts you "like," but much more sophisticated.</p><p>The machine learning of quantum computers could help us do a lot of things much faster and much more efficiently, and continued improvement of the function of quantum computers by quantum computers could lead to things like semi-automatic vehicles and other advanced forms of artificial intelligence.</p><p>All of these applications are exciting, but we've got a ways to go before they're available. Still, some of the major players working on quantum computers include Google and NASA, and when big companies like these get involved with new cutting edge technology like this, we usually don't have to wait that long for big breakthroughs.</p><p>Johnson thinks we are on the cusp of big discoveries that will open up these applications, but they're really just the beginning.</p><p>"I think it's going to have many many applications that we can't even think of today," Johnson said.</p>    <div class="margin-top">        <h3>NOW WATCH: <a href="http://www.businessinsider.com/johannes-kepler-math-theory-spherical-objects-2014-9">A Computer Just Solved A 400-Year-Old Math Problem About The Best Way To Stack Balls</a></h3>        <div>            <div>        <div class="ooyala-video-player" data-video-autoplay="false" data-video-id="IyamMycDrElYzzFi0OMAT1yporRy3NXE" data-player-variable="ooyalapopvideo" id="ooyalaplayer_popvideo" style="width:1280px;height:720px"></div>        </div>        </div>            </div>

7 awesome ways quantum computers will change the world

<p><div class="KonaFilter image-container display-table"><div><div class="image"></div></div></div></p><ul class="summary-list"><li>The <a href="https://www.businessinsider.com/10-billion-earth-like-planets-in-milky-way-galaxy-2019-8">Milky Way</a> could be teeming with <a href="https://www.businessinsider.com/alien-signals-search-for-extraterrestrial-intelligence-study-2018-10">extraterrestrial civilizations</a> that have <a href="https://www.businessinsider.com/fermi-paradox-drake-equation-aliens-elon-musk-2018-6">spread across the stars</a>, according to a new study.</li><li>The study offers new perspectives on <a href="https://www.businessinsider.com/climate-change-could-answer-fermi-paradox-2018-6">the Fermi Paradox</a>, which asks why we haven't found signs of intelligent extraterrestrials in our galaxy.</li><li>There are plenty of scenarios in which aliens could exist but we haven't heard from them, the study authors wrote. <a href="https://www.businessinsider.com/40th-anniversary-of-alien-movie-aliens-in-film-changes-2019-8">Aliens</a> may have even <a href="https://www.businessinsider.com/pentagon-ufo-alien-research-program-footage-nytimes-2017-12">visited Earth</a>, they say, just not recently enough for us to have noticed.</li><li>The study suggests that aliens might wait for stars to move closer to one another before <a href="https://www.businessinsider.com/nasa-10-year-plan-lunar-base-saturn-moon-2019-7">spreading across the galaxy</a></li><li><a href="https://www.businessinsider.com/?hprecirc-bullet">Visit Business Insider's homepage for more stories</a>.</li></ul><p>The <a href="https://www.businessinsider.com/new-3d-map-of-milky-way-warped-shape-2019-7">Milky Way</a> could be teeming with interstellar alien civilizations, according to a new study. We just don't know about it because they haven't paid us a visit in 10 million years.</p><p>The <a href="https://iopscience.iop.org/article/10.3847/1538-3881/ab31a3#ajab31a3s5">study</a>, published last month in The Astronomical Journal, posits that intelligent extraterrestrial life could be taking its time to explore the galaxy, harnessing star systems' movement to make star-hopping easier.</p><p>The work is a new response to a question known as the <a href="https://www.businessinsider.com/search-for-aliens-fermi-paradox-solution-planetary-scientist-alan-stern-2017-12">Fermi Paradox</a>, which asks why we haven't detected signs of extraterrestrial intelligence.</p><p>The paradox was first posed by physicist Enrico Fermi, who famously asked: "Where is everybody?"</p><p><div class="KonaFilter image-container display-table"><div><div class="image"></div></div></div></p><p>Fermi was <a href="https://www.businessinsider.com/astronomy-geology-physics-science-myths-2016-3#">questioning the feasibility of travel between stars</a>, but since then, his query has come to represent doubts about the very existence of extraterrestrials. Astrophysicist Michael Hart explored the question formally when he argued in a 1975 <a href="http://articles.adsabs.harvard.edu/full/1975QJRAS..16..128H/0000128.000.html">paper</a> that there has been plenty of time for intelligent life to colonize the Milky Way in the 13.6 billion years since the galaxy first formed, yet we've heard nothing from them. Hart concluded that there must be no other advanced civilizations in our galaxy.</p><p>The new study offers a different perspective on the question: Maybe aliens are just taking their time and being strategic, the authors suggest.</p><p>"If you don't account for motion of stars when you try to solve this problem, you're basically left with one of two solutions," Jonathan Carroll-Nellenback, a computational scientist and the study's lead author, told Business Insider. "Either nobody leaves their planet, or we are in fact the only technological civilization in the galaxy."</p><p>Stars (and the planets around them) orbit the center of the galaxy on different paths at different speeds. As they do, they occasionally pass each other, Carroll-Nellenback pointed out. So aliens could be waiting for their next destination to come closer to them, his study says.</p><p>In that case, civilizations would take longer to spread across the stars than Hart estimated. So they may not have reached us yet ⁠- or maybe they did, long before humans evolved.</p><h2>A new idea about interstellar travel</h2><p><div class="KonaFilter image-container display-table"><div><div class="image"></div></div></div></p><p>Researchers have sought to answer the Fermi Paradox in a number of ways - studies have investigated the possibility that all alien life <a href="https://www.businessinsider.com/search-for-aliens-fermi-paradox-solution-planetary-scientist-alan-stern-2017-12">forms in oceans below a planet's surface</a>, and posited that civilizations may get <a href="https://www.businessinsider.com/climate-change-could-answer-fermi-paradox-2018-6">undone by their unsustainability</a> before accomplishing any interstellar travel. There's also the "<a href="https://www.technologyreview.com/s/602302/galactic-model-simulates-how-et-civilizations-could-be-deliberately-avoiding-earth/">zoo hypothesis</a>," which imagines that Milky Way societies have decided not to contact us for the same reasons that we have nature preserves or maintain protections for some uncontacted indigenous peoples.</p><p>A <a href="https://arxiv.org/abs/1806.02404">2018 Oxford University study</a>, meanwhile, suggested that there's a roughly 2-in-5 chance we're alone in our galaxy and a 1-in-3 chance we're alone in the entire cosmos.</p><p>But the authors of the newest study point out that previous research hasn't accounted for a crucial fact of our galaxy: It moves. Just as planets orbit stars, star systems orbit the galactic center. Our solar system, for example, orbits the galaxy every 230 million years.</p><p>If civilizations arise in star systems far away from the others (like our own, which is in the backwaters of the galaxy), they could make the trip shorter by waiting until their orbital path brings them closer to a habitable star system, the study says. Then once settled in that new system, the aliens could wait again for an optimal travel distance to make another hop, and so on.</p><p><div class="KonaFilter image-container display-table"><div><div class="image"></div></div></div></p><p>In this scenario, aliens aren't jet-setting across the galaxy. They're just waiting long enough for their star to get close to another star with a habitable planet.</p><p>"If long enough is a billion years, well then that's one solution to the Fermi paradox," Carroll-Nellenback said. "Habitable worlds are so rare that you have to wait longer than any civilization is expected to last before another one comes in range."</p><h2>The Milky Way could be full of settled star systems</h2><p>To explore the scenarios in which aliens could exist, the researchers used numerical models to simulate a civilization's spread across the galaxy. They factored in a variety of possibilities for a hypothetical civilization's proximity to new star systems, the range and speed of its interstellar probes, and the launch rate of those probes. </p><p><div class="KonaFilter image-container display-table"><div><div class="image"></div></div></div></p><p>The research team did not attempt to guess at aliens' motivations or politics - a tendency that some astronomers view as a pitfall in other Fermi Paradox solutions. </p><p>"We tried to come up with a model that would involve the fewest assumptions about sociology that we could," Carroll-Nellenback said.</p><p>Still, part of the problem with modeling the galactic spread of alien civilizations is that we're only working with one data point: ourselves. So all our predictions are based on our own behavior. </p><p>But even with this limitation, the researchers found that the Milky Way could be filled with settled star systems that we don't know about. That still held true when they used conservative estimates of the speed and frequency of aliens' interstellar travel.</p><p>"Every system could be habitable and could be settled, but they wouldn't visit us because they're not close enough," Carroll-Nellenback said, though he added that just because that's possible doesn't make it likely. </p><p><div class="KonaFilter image-container display-table"><div><div class="image"></div></div></div></p><p>So far, we've detected about 4,000 planets outside our solar system and none have been shown to host life. But we haven't looked that hard: There are at least 100 billion stars in the Milky Way, and even more planets. One recent study <a href="https://www.businessinsider.com/10-billion-earth-like-planets-in-milky-way-galaxy-2019-8">estimated that up to 10 billion of those planets could be Earth-like</a>.</p><p>So the study authors wrote that concluding that none of those planets hold life would be like looking at a pool-sized amount of ocean water and finding no dolphins, then deciding that the entire ocean has no dolphins.</p><h2>Aliens may have visited Earth in the past</h2><p>Another key element in debates about alien life is what Hart called "Fact A": There are no interstellar visitors on Earth now, and there is no evidence of past visits.</p><p>But that doesn't mean they were never here, the authors of the new study say.</p><p><div class="KonaFilter image-container display-table"><div><div class="image"></div></div></div></p><p>If an alien civilization came to Earth millions of years ago (the Earth is 4.5 billion years old), there might be no remaining signs of their visit, the authors wrote. They pointed to <a href="https://www.sciencedirect.com/science/article/pii/S0094576511003122">previous</a> <a href="https://www.sciencedirect.com/science/article/pii/S0094576511002323">research</a> <a href="https://arxiv.org/abs/1804.03748">suggesting</a> that we may not be able to detect evidence of past alien visits.</p><p>It's even possible that aliens have passed near Earth since we've been here, but decided not to visit. The paper calls this the "Aurora effect," named for Kim Stanley Robinson's novel "Aurora." </p><p>What's more, aliens might not want to visit a planet that already has life, the authors said. To assume that they would, they added, would be a "naive projection" of a human tendency to equate expansion with conquest.</p><p>The study accounted for all of these considerations - the calculations assumed that alien civilizations would only settle a fraction of the habitable worlds they encountered. Still, the researchers said, if there are enough habitable worlds, aliens could easily have spread across the galaxy by now.</p><h2>There's still much more to learn</h2><p>For now, the researchers don't think we should get discouraged by any perceived silence from the universe.</p><p>"It doesn't mean that we're alone," Carroll-Nellenback said. "It just means that habitable planets are probably rare and hard to get to."</p><p>In the next few years, our ability to detect and observe other potentially habitable planets is expected to improve dramatically as new telescopes get built and launched into space.</p><p><div class="KonaFilter image-container display-table"><div><div class="image"></div></div></div></p><p>The Kepler telescope made leaps and bounds in the search for planets that might host life in our galaxy. In Earth's orbit today, the <a href="https://www.businessinsider.com/hubble-telescope-galaxies-photo-legacy-wide-field-deep-universe-2019-5">Hubble Space Telescope</a> and <a href="https://www.businessinsider.com/nasa-tess-telescope-habitable-world-31-light-years-away-2019-7">Transiting Exoplanet Survey Satellite (TESS)</a> are continuing the search. NASA is also building the <a href="https://www.businessinsider.com/nasa-10-year-plan-lunar-base-saturn-moon-2019-7">James Webb Space Telescope</a>, which may be able to see as far through space and time as the Big Bang. It's slated to launch in 2021.</p><p>Of course, what would really improve scientists' ability to estimate the probability that we're alone in the universe would be more data on the speed or ranges of interstellar probes. A better sense of how long hypothetical alien civilizations last would be useful, too. </p><p>"We're in desperate need of some data points," Carroll-Nellenback said.</p>

Alien civilizations may have explored the galaxy and visited Earth already, new study says. We just haven't seen them recently.

<p></p><div class="KonaFilter image-container display-table float_right"><div><div class="image on-image"></div><p></p></div></div>Nintendo's Mario series is the <a href="http://www.mariowiki.com/Mario_(series)">best-selling</a>&#xa0;video game franchise in history. And with moves like Mario's it's no mystery why so many people enjoy navigating the little Italian through his fantasy world of princesses, castles, and magical mushrooms. But there's a fundamental flaw in the game: In our universe, Mario World physically couldn't exist.<p>This tiny yet surprising flaw in the game was recently discovered by the PBS video series <a href="https://www.youtube.com/watch?v=McsgRggUjE4">Space Time</a> when they used some simple math and basic physics to determine what kind of planet Mario lives on.</p><h2>How does Mario jump so high?</h2><p>You'll notice in the gif below that Mario has some very impressive jumping skills:</p><p></p><div class="KonaFilter image-container display-table full"><div><div class="image on-image"></div><p></p></div></div>At first, you might think that Mario can jump so high because he's on a planet that is smaller than Earth and, therefore, has lower gravity.<p>The Moon, for example, has about one-sixth Earth's gravity, which means you can jump six times higher on the Moon than on Earth using the same leg power. But that's not the full story.</p><p>The crucial detail is not how high Mario jumps but how fast he falls.</p><p></p><div class="KonaFilter image-container display-table full"><div><div class="image on-image"></div><p></p></div></div>Although you can jump six times higher on the Moon, it would take six times longer to fall back to the ground than you would on Earth. If Mario fell that slowly, it would make for some pretty boring gameplay.<p></p><div class="KonaFilter image-container display-table full"><div><div class="image on-image"></div><p></p></div></div><p>Since Mario moves relatively quickly through the air he must be on a planet that has pretty strong gravity. You can easily calculate how strong the gravity in Mario World is with two simple parameters:</p><ul><li>How high Mario jumps.</li><li>How long it takes Mario's to fall to the ground.</li></ul><p>By crudely measuring these factors, Gabe from Space Time determined that in the Mario World game on Super Nintendo Entertainment System from 1991, Mario jumps about 2.25 times his own height and takes approximately 0.3 seconds to fall to the ground.</p><p></p><div class="KonaFilter image-container display-table float_right"><div><div class="image on-image"></div><p></p></div></div>After crunching the numbers, Gabe calculates that Mario is on a world that has eight times stronger gravity than on Earth. Keep in mind that most humans can't withstand anything stronger than <a href="http://en.wikipedia.org/wiki/G-force#Human_tolerance_of_g-force">five times</a> Earth's gravity before passing out.<p>To put this into better perspective: If you weigh 150 pounds on Earth, you would weigh 1200 pounds on Mario's planet!</p><p>So, how does Mario jump so high with all of those pounds weighing him down?</p><p>Pure leg strength, Gabe concludes. He must do a lot of dead lifts off screen.</p><p>In fact, if Mario were on Earth, his strength would allow him to jump over 90 feet off the ground. To achieve that kind of height, he would have a lift off speed of more than 50 miles-per-hour!</p><p>Now, Mario's jumping ability slightly varies between different games, so the g-value will also vary. But, in general, <a href="http://hypertextbook.com/facts/2007/mariogravity.shtml">people have found</a> that this value is between 5 and 10 times Earth's gravity - stronger than anything we experience on a daily basis. You might reach 5 g's when you're speeding through a 360-degree loop on a roller coaster.</p><h2>Which planet is Mario's?</h2><p>There's no planet in our solar system that even comes close to the kind of gravity on Mario's many worlds. Jupiter, the largest planet orbiting our sun, has about 2.5 times Earth's gravity. So, if you weighed 150 pounds on Earth, you would weigh weigh 355 pounds on Jupiter. That's not even close to the gravity on Mario World.</p><p></p><div class="KonaFilter image-container display-table full"><div><div class="image on-image"></div><p></p></div></div>While Mario might not be in our solar system, there's a possibility he might be outside of it - in another star system far from Earth.<p>Because of our search for exoplanets outside of our solar system, we know that there are plenty of weird planets out there. But are they weird enough?</p><p>NASA's Kepler Space Telescope, we've found more than <a href="http://exoplanetarchive.ipac.caltech.edu/">1,800</a> planets orbiting stars other than the sun, <a href="http://exoplanets.findthedata.com/saved_search/Farthest-Exoplanets-From-Earth">thousands of light years</a> from Earth. Could one of them have conditions similar to those on Mario World?</p><p>First, Mario clearly lives on a rocky planet with an atmosphere similar to Earth's. But it also has 8 times the gravity of Earth - is such a planet possible?</p><p>Unfortunately, a planet like this doesn't seem likely to exist in our universe because of <a href="http://www.universetoday.com/13757/how-big-do-planets-get/">how we think large planets form</a>. In order to have a lot of gravity the planet must have a lot of mass, and the exoplanets that even get close to large enough seem to be gas giants, like Jupiter and Saturn, with no ground to speak of.</p><p>Even the planet with the strongest gravity known so far is around 4 g's - about half the gravity that Gabe calculated on Mario World.</p><p>So, as Earth-like as his world may appear on screen, there's no planet in the universe that would give us moves like Mario.</p><p>Check out <a href="https://www.youtube.com/watch?v=McsgRggUjE4">the PBS video</a> below:</p><div><div></div></div>    <div class="margin-top">        <h3>NOW WATCH: <a href="http://www.businessinsider.com/robot-plays-beer-pong-2014-12">Watch This Robot Play A Perfect Game Of Beer Pong</a></h3>        <div>            <div>        <div class="ooyala-video-player" data-video-autoplay="false" data-video-id="ZoazNrcjq1G5LDCM9egkzaasdA6jUuBz" data-player-variable="ooyalapopvideo" id="ooyalaplayer_popvideo" style="width:1280px;height:720px"></div>        </div>        </div>            </div>

The physics of Mario World shows the game has a fundamental flaw

<p><div class="KonaFilter image-container display-table"><div><div class="image on-image"><p class="source"><span><a href="https://www.shutterstock.com/image-illustration/extrasolar-planet-earthlike-exoplanet-on-background-600502655">Shutterstock</a></span></p><p class="caption">An illustration of Earth-like exoplanets</p></div><p></p></div></div></p><ul><li><strong>Astronomers have detected what may be four roughly Earth-size planets orbiting Tau Ceti, the nearest sun-like star.</strong></li><li><strong>Two of the worlds appear to orbit within Tau Ceti's habitable zone, though a cloud of debris and asteroids may pose a threat to any life on them.</strong></li><li><strong>If the result is confirmed, independent astronomers say it would be "astonishing.</strong></li></ul><p>Astronomers may have just hit a crucial milestone in the search for other Earth-like planets. Scientists from the University of Hertfordshire and University of California, Santa Cruz announced they've discovered four planets orbiting a nearby, sun-like star - two of which may be habitable.</p><p>Researchers have turned up thousands of planet candidates in recent years, <a href="http://www.businessinsider.com/new-exoplanets-nasa-kepler-mission-data-2017-6">about 10</a> of which may be small, rocky, and habitable like the Earth. You'd think most of these worlds would orbit suns like ours, but that's not the case, since such stars are so big and bright that they easily drown out the faint signals of tiny planets.</p><p>That's why the new discovery of four roughly Earth-size worlds  - some 12 light-years away from our solar system - is all the more exciting.</p><p>"If true this discovery is absolutely phenomenal - that one of our nearest neighboring sun-like stars might have rocky worlds," <a href="http://www.saraseager.com/" target="_blank" rel="noopener noreferrer">Sara Seager</a>, a planetary scientist at MIT who wasn't involved in the research, told Business Insider in an email.</p><h2>Worlds in the closest sun-like solar system</h2><p>The suspected planets all orbit Tau Ceti, a star located 11.9 light-years away from us, according to a forthcoming study in The Astrophysical Journal. (You can read a pre-print version of the paper <a href="https://arxiv.org/abs/1708.02051" target="_blank" rel="noopener noreferrer">on arXiv</a>.)</p><p>The star is about three-quarters the mass of the sun, but its brightness and color are very sun-like. It's the closest sun-like star to Earth.</p><p>The planets' sizes aren't known yet, but they're estimated to have about 1.7 times the Earth's mass. That would make them the smallest planets ever detected around a distant sun-like star, according to a press release emailed by the University of Hertfordshire.</p><p>Two of the four worlds orbit in a searing-hot zone close to Tau Ceti. The other two "super-Earths" seem to orbit within a "Goldilocks" habitable zone, where water on the surface can be liquid (rather than frozen solid or boiled away), according to <a href="https://news.ucsc.edu/2017/08/tau-ceti-planets.html">a press release</a> by the University of California Santa Cruz.</p><p><div class="KonaFilter image-container display-table"><div><div class="image on-image"><p class="source"><span>Fabo Feng/University of Hertfordshire</span></p></div><p></p></div></div></p><p>Two things make this particular discovery stunning to astronomers like Seager.</p><p>First, our solar system is the only place we know where life exists, which means that sun-like stars may be the best places to look for life (though there is some debate about whether <a href="http://www.businessinsider.com/red-dwarf-planets-proxima-b-aliens-2016-8/">smaller, cooler red dwarf stars</a> could be better to explore).</p><p>Second, it's incredibly difficult to spy a relatively tiny planet in the figurative shadow of a sun-like star.</p><p>"Earth is so small in mass compared to its host sun-like star that finding the signal amidst the noise is really like finding the proverbial needle in a haystack," Seager added. "The authors have come up with a special technique to get rid of the noise to find the signal. It's always a tricky situation to look for very weak signals."</p><h2>Scouting for tiny wobbles</h2><p>Most planets are detected by a "<a href="http://archive.seti.org/seti/seti-science/detecting_new/wobble_method.php" target="_blank" rel="noopener noreferrer">wobble method</a>," where a planet slightly jerks around its star.</p><p>Such wobbles or wiggles (technically called Doppler shifts) come from planets sharing a center of gravity that doesn't reside precisely in the middle of a star. Jupiter, for example, actually <a href="http://www.businessinsider.com/jupiter-orbits-center-mass-near-sun-2017-7">orbits a spot</a> some 30,000 miles above the sun's surface - and not in a perfect circle.</p><p><div class="KonaFilter image-container display-table"><div><div class="image on-image"><p class="source"><span><a href="https://www.nasa.gov/feature/goddard/2016/satellites-to-see-mercury-enter-spotlight-on-may-9">NASA/SDO; Business Insider</a></span></p><p class="caption">A to-scale illustration of where the sun-Jupiter barycenter is located.</p></div><p></p></div></div></p><p>This wobbling causes slight speeding up and slowing down of a star as a planet orbits it, leaving an imprint on the light the star emits.</p><p>In their new study, the team detected variations on the order of 30 centimeters per second - a gap of about 2/3 of a mile per hour. Astronomers think they'll need a sensitivity three times better (about 0.2 mph) to reliably detect Earth analogs around sun-like stars.</p><p>"We're getting tantalizingly close to observing the correct limits required for detecting Earth-like planets," <a href="http://researchprofiles.herts.ac.uk/portal/en/persons/fabo-feng(acca848b-f213-4814-9571-48b80b525e74).html" target="_blank" rel="noopener noreferrer">Fabo Feng</a>, an astrophysicist at the University of Hertfordshire who led the research, said in the press release. "Our detection of such weak wobbles is a milestone in the search for Earth analogs and the understanding of the Earth's habitability through comparison with these [new planets]."</p><p><div class="KonaFilter image-container display-table float_right"><div><div class="image on-image"><p class="source"><span><a href="http://www.keckobservatory.org/fans">W.M. Keck Observatory</a></span></p><p class="caption">The Keck I and Keck II telescopes on Mauna Kea in Hawaii.</p></div><p></p></div></div>To find the planets, it took Feng and his colleagues four years to sift through, analyze, and model the data gathered by two telescope instruments: the European Southern Observatory's <a href="https://www.eso.org/sci/facilities/lasilla/instruments/harps.html" target="_blank" rel="noopener noreferrer">HARPS spectrograph</a> in Chile and the W.M. Keck Observatory's <a href="https://www2.keck.hawaii.edu/inst/hires/" target="_blank" rel="noopener noreferrer">HiRes instrument</a> in Hawaii.</p><p>Seager emphasized that "it would take a long time" for other astronomers to replicate and verify the discovery.</p><p>"There is no sugar-coating how hard it is to find an Earth-mass planet signal in a sun-like star, due to star noise and instrument noise," Seager said.</p><h2>Two hits to habitability</h2><p>Small, rocky worlds in a habitable zone <a href="http://www.businessinsider.com/goldilocks-exoplanet-habitability-internal-heat-2016-8">aren't necessarily cozy environments for life</a>.</p><p>One possible problem with Tau Ceti's two habitable-zone-worlds is their unknown size.</p><p>"They surely don't conclude that the four planets are Earth-sized, because the method they used to detect them provides no information on their sizes," Michaël Gillon, an astronomer at the Université de Liège who wasn't involved in the study, told Business Insider in an email. (Gillon helped with the <a href="http://www.businessinsider.com/earth-like-planets-seven-trappist-1-system-2017-02">discovery of the seven Earth-size planets</a> orbiting the TRAPPIST-1 star system.)</p><p>"All they can say is that each planet is more massive than X Earth-masses," he said. In the case of Tau Ceti, this lower limit seems to be about 1.7 times as hefty as Earth, and it's uncertain if complex life could thrive on a planet like this.</p><p>Another problem is the debris.</p><p><div class="KonaFilter image-container display-table"><div><div class="image on-image"><p class="source"><span><a href="https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA06939">NASA/JPL-Caltech</a></span></p></div><p></p></div></div></p><p>In fact, estimates suggests that the Tau Ceti system has r<a href="https://www.wired.com/2012/12/5-exoplanets-tau-ceti/">oughly 10 times the mass of asteroids (and dust)</a> than our solar system.</p><p>That's not a great sign, because asteroid impacts are known to <a href="http://www.businessinsider.com/how-earth-will-end-apocalypse-2016-11">wipe out vast numbers of species</a>.</p><p>Still, Seager characterized the result as "astonishing." Once the planets are confirmed by other researchers, she added, it could be "a tremendous milestone en route to finding our Earth twin."</p>    <div class="margin-top">        <h3>NOW WATCH: <a href="http://www.businessinsider.com/stephen-hawking-warning-space-aliens-seti-2016-12">Stephen Hawking warned us about contacting aliens, but this astronomer says it's 'too late'</a></h3>        <div>                    </div>    </div>

An 'absolutely phenomenal' discovery hints 4 Earth-size planets may orbit the closest sun to our own

<p></p><div class="KonaFilter image-container display-table float_right"><div><div class="image on-image"></div><p></p></div></div>Astronomers using a telescope in Chile have found evidence they are saying could be previously undetected worlds hiding at the farthest edges of our solar system.<p>The idea of a mysterious 'Planet X' lurking somewhere in our solar system is not new.</p><p>Research published just last year in the journal Nature found evidence of an object about <a href="http://www.techinsider.io/planet-x-biden-hiding-beyond-pluto-evidence-2015-9">4 times the size of Earth</a> that's floating way out beyond Pluto.</p><p>Now two new research papers using data from the Atacama Large Millimeter/Submillimeter Array (ALMA) have resurfaced the possibility of a Planet X lurking at the edge of the solar system.</p><p>The papers were published on a server called arXiv where some scientists publish rough versions of papers before they're peer-reviewed and accepted for publication in a journal. The scientists use this "pre-publishing" to engage other experts in their field and get feedback.</p><p>The papers have launched a <a href="http://www.scientificamerican.com/article/astronomers-skeptical-over-planet-x-claims/">heated debate</a> among astronomers about whether a "Planet X" may really exist or not.</p><p>The <a href="http://arxiv.org/pdf/1512.02652v1.pdf">first paper</a> is about an object detected in the same part of the sky as our neighboring binary star Alpha Centauri. The researchers detected a moving object near the star system. It's labeled as U in the image below:</p><p></p><div class="KonaFilter image-container display-table full"><div><div class="image on-image"></div><p></p></div></div>They have three guesses for what it might be: a small icy chunk about 9 billion miles away from Earth, a "super Earth" (that would fit the bill of "Planet X") orbiting somewhere around 28 billion miles away from Earth, or it could be a brown dwarf (an object too large to be called a planet but too small to be called a star) much farther away - about 20,000 Astronomical Units (AU) from Earth. (One AU is about 93 million miles.)<p>The <a href="http://arxiv.org/abs/1512.02650">second paper</a> describes evidence of another moving object in the same part of the sky as the star W Aquilae. The researchers have nicknamed it "Gna," and they say it could be a small body only a few hundred miles wide (they classify it as a "<a href="http://news.discovery.com/space/asteroids-meteors-meteorites/centaurs-cross-dressing-comets-that-go-s-asteroids-130725.htm">centaur" object</a> which is a type of minor planet) orbiting on the outskirts of our solar system somewhere between 12 and 25 AU away (between the orbits of Saturn and Neptune). Alternatively, it could be a very distant planet-sized object 4,000 AU away.</p><p>However, other researchers have pointed out two big problems with these claims.</p><p>The ALMA telescope has a very small field of view and the astronomers only made a few observations of either object. They weren't able to track them for very long. So it's possible that it's just a data glitch.</p><p>Astronomer Mike Brown pointed out on Twitter why it's unlikely that ALMA could have spotted something planet-sized with its tiny field of view:</p><p><div></div></p><p><div></div></p><p><div></div></p><p>And as astronomer Phil Plait pointed out in a <a href="http://www.slate.com/blogs/bad_astronomy/2015/12/10/extreme_tnos_very_distant_solar_system_objects_may_have_been_found.html">Slate blog post</a>, if either object does exist, it seems much more likely that they're one of the thousands of <a href="https://pds.jpl.nasa.gov/planets/special/smbod.htm">trans-Neptunian objects</a> (TNOs) in our solar system - small icy bodies that are floating out beyond Neptune. Pluto and Eris are examples of TNOs. TNOs are much smaller than actual planets.</p><p>Wouter Vlemmings, an astronomer that worked on both papers, told Tech Insider in an email that the research is not conclusive and that's why both papers were published on arXiv. (They've both been submitted to the journal of Astronomy &amp; Astrophysics.)</p><p>Here's what Vlemmings described as the most likely explanation for the observations:</p><p>Vlemmings and the other researchers hope to examine the objects more closely in the future.</p><p>While we have a lot of reason to be skeptical about these new papers, it seems there's more evidence that there's something going on in the outer solar system that we can't totally explain yet.</p><p>Whether or not it's an elusive Planet X remains to be seen.</p>    <div class="margin-top">        <h3>NOW WATCH: <a href="http://www.businessinsider.com/hidden-iphone-map-reveals-location-2015-11">There's a hidden map in your iPhone of everywhere you've been</a></h3>        <div>            <div>        <div class="ooyala-video-player" data-video-autoplay="false" data-video-id="h1ZzV4eDrFeMVarsiwx5YaP_PbbKypBn" data-player-variable="ooyalapopvideo" id="ooyalaplayer_popvideo" style="width:1280px;height:720px"></div>        </div>        </div>            </div>

Here's why people are saying we may have found a mysterious 'Planet X'

<p><div class="KonaFilter image-container display-table float_right"><div><div class="image on-image"></div><p></p></div></div>There are <a href="http://phl.upr.edu/projects/habitable-exoplanets-catalog">over two dozen exoplanets</a> in our galaxy that have the potential to harbor life, not to mention the numerous other habitable worlds that could exist in the other 100 billion galaxies throughout the universe.</p><p>Considering the numbers, the chances for life existing <span style="line-height: 1.5em;">beyond Earth look good. However, the chances of detecting that life are less certain. </span></p><p>Why? For one thing, we simply don't know what that alien life will look like. </p><p><strong>"It could be so utterly different that it could be staring us in the face and we would not be able to understand that it is life,"</strong> Christopher Adami, a professor of microbiology and molecular genetics at Michigan State University, told Business Insider. </p><h2><span>Beyond carbon-based life</span></h2><p><span style="background-color: #ffffff;">All life on Earth is carbon-based, meaning the organic molecules that comprise every living organism known to man contain carbon atoms bonded with other atoms. For example, one of the simplest organic compounds - methane - has one carbon atom and four hydrogen atoms.</span></p><p><span><span style="background-color: #ffffff;">But other lifeforms could be based on something else entirely. </span>Take Saturn's moon Titan, for example. It's rich with lakes of liquid methane on the surface. These lakes could harbor </span><span></span><a href="http://www.iflscience.com/space/template-methane-based-life-forms-titan">methane-based life forms</a> that are vastly different from the<span> carbon-based life we have here on Earth. I</span><span style="line-height: 1.5em;">f our instruments for detecting life are only designed to test for life like us, however, we may never know if life on Titan, or other life with different chemistry on other worlds, exists.</span></p><p><span style="line-height: 1.5em;">Adami is working on a way around this problem. He presented his approach at the <a href="http://meetings.aps.org/Meeting/APR15/Session/E12">2015 APS April meeting</a>. </span></p><p><span style="background-color: #ffffff;">In the early '90s,</span> he helped develop a highly sophisticated computer program called <a href="http://devolab.msu.edu/software/">Avida</a>. The program studies how digital organisms - computer programs with the ability to self-replicate and mutate without human intervention - evolve over time. S<span>cientists </span><span>use programs like these to better understand the traits that drive Darwinian evolution. Their </span><span style="line-height: 1.5em;">artificial self-replication process makes them a great analog for real life on Earth.</span></p><p><span style="line-height: 1.5em;">Adami has bigger plans for Avida, however. </span></p><h2>Life's universal theme</h2><p><div class="KonaFilter image-container display-table float_right"><div><div class="image on-image"></div><p></p></div></div>He's looking for a trait that all life forms across the universe would possess - a universal theme of sorts that would go beyond the chemicals they're made of.</p><p>If this universal theme exists and we knew how to identify and test for it, we could quickly identify life on other moons or planets, even if that life has a completely different chemistry compared to life on Earth.</p><p>Adami thinks he's pretty close to finding this theme.</p><p>"There are in fact things that are universal to all forms of life, everywhere, and what that is, is information," Adami said. "Basically information is that which allows you to make predictions. And all living systems have to do that."</p><p><span style="line-height: 1.5em;">This information is stored inside of every organism's genome -</span><span style="line-height: 1.5em;"> <span style="background-color: #ffffff;">the complete set of their genes.</span> A good way to picture this information is to think of it as individual pieces, or bits, like the bits that computers use to communicate. <span style="background-color: #ffff00;"><br /></span></span></p><p><span style="line-height: 1.5em;">A single strand of human DNA, for example,<span style="background-color: #ffffff;"> likely contains hundreds of millions </span>of these information "bits," says Adami. And the way organisms evolve, he says, depends on how these so-called bits replicate and mutate over time. </span></p><p><span style="line-height: 1.5em;">In a lecture, famed astrophysicist <a href="http://www.hawking.org.uk/life-in-the-universe.html">Stephen Hawking talks about</a> how the information in our DNA has "probably changed by only a few million bits" over the last several million years as we evolved from apes. </span></p><p><span style="line-height: 1.5em;">Of course, Hawking is an astrophysicist and not an evolutionary biologist, so this theory should be taken with a grain of salt. But he's not the only one to suggest the <a href="http://www.evolutionnews.org/2014/01/when_biology_tr081551.html">evolution is driven by changes</a> in our genome's information bits.</span></p><h2><span style="line-height: 1.5em;">The big question</span></h2><p><span style="line-height: 1.5em;"><div class="KonaFilter image-container display-table float_right"><div><div class="image on-image"></div><p></p></div></div>The big question is how to distinguish between</span><span style="line-height: 1.5em;"> the information stored in molecules in living organisms and<span style="background-color: #ffffff;"> the ones stored in</span> non-living objects. </span></p><p><span style="line-height: 1.5em; background-color: #ffffff;">One way of doing this is by looking for patterns, says Adami. </span></p><p><span style="line-height: 1.5em;">Unlike living things, which generate specific patterns as they self-replicate and reproduce (like how sequences in our <a href="http://www.ncbi.nlm.nih.gov/pubmed/15921050">DNA repeat themselves</a>), things that are not living </span><span style="line-height: 1.5em;">will have only random bits of information that never repeat at regular frequencies. </span></p><p><span style="line-height: 1.5em;">So the task is this: Find the repeated sequences. </span></p><p><span style="line-height: 1.5em;">Unfortunately, that's easier said than done.</span></p><p><span style="line-height: 1.5em;">The best way to do it, he says, is to take a look at the chemicals inside the soils of other moons and planets in our solar system. No one has begun doing this yet. There are no instruments on board NASA's Mars rovers that use Adami's method </span><span style="line-height: 1.5em;">and we have no working rovers on other planets or moons at this time. </span></p><h2>A fourth domain of life? </h2><p><div class="KonaFilter image-container display-table float_right"><div><div class="image on-image"></div><p></p></div></div><span style="background-color: #ffff00;"></span></p><p><span style="background-color: #ffffff;">Although discovering alien life within the soils of other worlds might be far off, scientists on Earth are aiming to hunt down life forms never-before discovered. Their approach is o</span><span style="line-height: 1.5em;"><span style="background-color: #ffffff;">n</span>e of the most promising experiments that could ultimately help us find extraterrestrials</span></p><p><span style="line-height: 1.5em;">In November, 2014, </span><span style="line-height: 1.5em;">a team of researchers at the </span><a href="http://jgi.doe.gov/discovering-undiscovered-tools-microbial-tree-of-life/">Joint Genome Institute</a> proposed an experiment that would<span style="line-height: 1.5em;"> search for a fourth domain of life here on Earth.</span></p><p><span style="line-height: 1.5em;">Right now there are only three known domains of life. The three domains are <a href="http://en.wikipedia.org/wiki/Three-domain_system">archaea, bacteria, and eukaryote</a> where each domain has a specific sequence in their RNA gene structure that distinguishes them from the other two groups. </span></p><p><span style="line-height: 1.5em;">But the team at JGT suspects that there might be a fourth domain with an RNA sequence completely unlike anything seen before.</span></p><p><span style="line-height: 1.5em;">"We are poised, armed with a new toolkit of powerful genomic technologies to generate and mine the increasingly large data sets to discover new life that may be strikingly different from those that we cataloged thus far," said JGI director </span><a href="http://jgi.doe.gov/about-us/organization/strategic-management/eddy-rubin/" target="_blank" title="Eddy Rubin">Eddy Rubin</a><span style="line-height: 1.5em;"> in a </span><a href="http://jgi.doe.gov/discovering-undiscovered-tools-microbial-tree-of-life/">statement</a><span style="line-height: 1.5em;">. </span></p><p>To do this, the team wants <span style="background-color: #ffffff;">to take a look the genes of cells in tiny life forms th</span>at lived more than 2.3 billion years ago, at a time when <a href="http://en.wikipedia.org/wiki/Great_Oxygenation_Event">Earth's atmosphere had far less oxygen than it does today</a>. The low-oxygen conditions at that time might have spurred a genetically-unique life form that could even resemble life forms on other worlds that have little oxygen in their atmosphere, like Mars. <span style="line-height: 1.5em;">This coveted new life form is biology's version of "</span><span style="line-height: 1.5em;"></span><a href="http://www.newscientist.com/article/dn20265-biologys-dark-matter-hints-at-fourth-domain-of-life.html">dark matter</a><span style="line-height: 1.5em;">". </span></p><p><span style="line-height: 1.5em;">Whether it's on Earth or another world, there's certain to be exciting new advances in the search for new life. </span></p>    <div class="margin-top">        <h3>NOW WATCH: <a href="http://www.businessinsider.com/paul-allen-microsoft-discovers-battleship-japan-world-war-2015-3">Here's what Microsoft co-founder Paul Allen actually found at the bottom of the ocean in the Philippines</a></h3>        <div>            <div>        <div class="ooyala-video-player" data-video-autoplay="false" data-video-id="BmdzFyczpQ-4AzSpG2AiKMbH0Xk6GnaJ" data-player-variable="ooyalapopvideo" id="ooyalaplayer_popvideo" style="width:1280px;height:720px"></div>        </div>        </div>            </div>

How humans will discover alien life that might otherwise be invisible

<p><span class="KonaFilter image-container display-table float_right"><span><span data-post-image="" class="image on-image"></span><p></p></span></span></p>
<h2>BI Answers: How many planets in the universe have intelligent alien life?</h2>
<p>More important than finding life on another planet would be communicating with those life forms. Do aliens engage in pra<span style="color: #222222; font-size: 15px; line-height: 1.5em;">ctices like philosophy, religion, mathematics, medicine, and war? The only way to truly find out is to communicate with them.</span></p>
<p>Until the 1960s, however, no one had even thought about how many intelligent civilization might be out there. It took the innovative mind of Frank Drake, an astronomer and early pioneer in the search for extraterrestrial life, to find a way to answer this question. His simple, yet comprehensive, equation that he developed in 1961 is named the Drake Equation in his honor.</p>
<p><a href="http://www.seti.org/drakeequation">The Drake Equation</a> is intended to help clarify the kinds of things we would need to know to figure out how many intelligent civilizations like ours exist in our galaxy. It estimates the number of intelligent civilizations that we could detect or communicate with in our galaxy based on seven parameters.</p>
<p>Drake's equation looks like this: N=R*f<sub>p</sub>n<sub>e</sub>f<sub>l</sub>f<sub>i</sub>f<sub>c</sub>L. That's a big pile of symbols, but when you break it down into individual components, it's more clear and comprehensible:</p>
<ul>
<li>R*: How fast stars form in our galaxy.</li>
<li>f<sub>p</sub>: The percentage of stars that have planets.</li>
<li>n<sub>e</sub>: The number of earthlike planets around each star that has planets.</li>
<li>f<sub>l</sub>: The percentage of earthlike planets that develop life.</li>
<li>f<sub>i</sub>: The percentage of planets with life that develop intelligent life.</li>
<li>f<sub>c</sub>: The percentage of intelligent species that go on to create technology that could be detected by an outside civilization like ours. One example of this is radio signals.</li>
<li>L: The average number of years the advanced civilizations release detectable signals.</li>
</ul>
<p>When you multiply the first three numbers (R*f<sub>p</sub>n<sub>e</sub>) together, you get the rate at which earthlike planets are formed in our galaxy. The next three components (f<sub>l</sub>f<sub>i</sub>f<sub>c</sub>) tell us how likely it is that an advanced civilization like humans would evolve on an earthlike planet.</p>
<p><span class="KonaFilter image-container display-table float_right"><span><span data-post-image="" class="image on-image"></span><p></p></span></span>Multiply those values with the length of time that advanced civilizations communicate and voila: you have calculated the overall number of civilizations around us today.</p>
<p>Unfortunately, exact values for each of these components, especially the last four that involve life and intelligent civilizations, are not known. We can only make logical guesstimates.</p>
<p>While planet detection projects like the <a href="http://kepler.nasa.gov/">Kepler space telescope</a> have given us a better understanding of the number of planets in our galaxy, we know very little about the origins of life and the evolution of intelligent life, since we only have a single example. And this plague of not knowing is a big problem when it comes to using the Drake Equation.</p>
<p>This is because putting different values into the equation can lead to dramatically different results.</p>
<p>If we consider "optimistic" values, in which it's fairly common for life to arise and <a href="http://en.wikipedia.org/wiki/Drake_equation#Original_estimates">somewhat similar to those used by Drake and his associates</a> at the conference where the equation was first described, we would expect a huge number of civilizations in our galaxy.</p>
<p>On the other hand, if the Universe makes it hard for intelligent life to emerge, <a href="http://www.amazon.com/Rare-Earth-Complex-Uncommon-Universe/dp/0387952896/ref=sr_1_2?ie=UTF8&amp;qid=1420758629&amp;sr=8-2&amp;keywords=rare+earth">as the advocates of the "Rare Earth Hypothesis" sugges</a>t, we might be alone in the universe:</p>
<p><span class="KonaFilter image-container display-table full click-to-enlarge"><span><span data-post-image="" class="image"><a title_source="Business Insider/Andy Kiersz" title_caption="" class="zoomin" href="https://static-ssl.businessinsider.com/image/54a472ad6da81119318b4569-960/drake%20equation%20table.png"><span class="sprites click-to-enlarge-icon" title="Click to enlarge"></span></a><span class="source"><span>Business Insider/Andy Kiersz</span></span></span><p></p></span></span></p>
<p>The total number of civilizations that we calculate relies very heavily on our assumptions. Our optimistic estimates suggest a fairly crowded galaxy, with around 140,000 species like us living in the Milky Way. Turn the inputs down a couple orders of magnitude, as we do in our pessimistic assumptions, and life is so rare that only around 1% of galaxies like our own will be likely to host even one complex civilization.</p>
<p>The rate of star formation in our galaxy, at about seven per year, was estimated as a result of <a href="http://www.nasa.gov/centers/goddard/news/topstory/2006/milkyway_seven.html">a NASA and ESA study</a> based on data from the European Space Agency's INTEGRAL satellite. The other values are based on either pessimistic or optimistic assumptions about life in the universe.</p>
<p>The Kepler mission and other planet searches have made it pretty clear that planets themselves are common in our galaxy. There are even 47 exoplanets that have been dubbed <a href="http://en.wikipedia.org/wiki/List_of_potentially_habitable_exoplanets">potentially habitable</a> due to their similarity to Earth.</p>
<p>Furthermore, scientists at the Harvard-Smithsonian Center for Astrophysics just&#xa0;<a href="http://www.space.com/25219-drake-equation.html">announced</a> that Kepler had <a href="http://www.businessinsider.com/8-new-planets-that-could-support-life-2015-1">found eight new planets</a> that were similar in size to Earth and were orbiting in a region where the planets' temperatures would allow them to harbor liquid water - a key ingredient for life on Earth and potentially other planets, too.</p>
<p>And Kepler only looks at a small portion of our galaxy:</p>
<p><span class="KonaFilter image-container display-table"><span><span data-post-image="" class="image on-image"></span><p></p></span></span></p>
<p>The biggest differences between being alone in our galaxy and a busy network of alien neighbors come from the values we know the least about: the likelihood of life evolving on a planet, the likelihood of intelligent life, the likelihood of intelligent life developing advanced technology, like radio broadcasts and telescopes, that make communication possible, and the average lifespan of technological civilizations.</p>
<p><span class="KonaFilter image-container display-table float_left"><span><span data-post-image="" class="image on-image"></span><p></p></span></span>Nailing down some of these values is a hot area of research. Another group of scientists recently announced that they have found a way to determine if planets in other solar systems are rocky, like Earth, or gaseous, like Jupiter.</p>
<p>"To find a truly Earth-like world, we should focus on planets less than 1.6 times the size of Earth, because those are the rocky worlds," said Courtney Dressing of the Harvard-Smithsonian Center for Astrophysics in a <a href="http://www.cfa.harvard.edu/news/2015-03">statement</a>. Dressing is lead author of a paper detailing her team's results that has been accepted for publication in The Astrophysical Journal.</p>
<p>While most of the specific values in the Drake Equation remain unknown to us, Frank Drake's goal back in 1961 was to clarify what we should be looking for. As we continue looking deeper into the cosmos, and more closely at our sun's neighborhood, Drake's elegant and simple summary of the factors that determine how common life is in the Universe continues to be a useful guide in our search for another Earth and another intelligent civilization.</p>
<p><em>This post is part of a continuing series that answers all of your "why" questions related to <keyword id="41551" type="ENTERTAINMENT" weightage="100" keywordseo="science">science</keyword>. Have your own question? Email <a href="mailto:science@businessinsider.com">science@businessinsider.com</a>&#xa0;with the subject line "Q&amp;A"; tweet your question to&#xa0;<a href="https://twitter.com/BI_Science" target="_blank">@BI_Science</a>; or&#xa0;<a href="https://www.facebook.com/BusinessInsiderScience" target="_blank">post to our Facebook page</a>.</em></p>

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