Extremophiles are organisms that live in extreme environments; these environments are usually under high pressure and temperature. These organisms use certain enzymes, ‘extremozymes’, that help them exist in such an intense environment.
Extremophiles were more prominent in the evolutionary history of the planet. They date back to more than 40 million years ago, and they continue to flourish in these intense environments.
The most common extremophile is Deinococcus radiodurans. This is one of the most radiation-resistant organisms known. It can withstand the cold, acid, and dehydration, making it a polyextremophile. It can survive high levels of ionizing radiation. In the Guinness Book of World Records, it’s the strongest known bacterium in the world.
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Fermi’s paradox is the paradox where is there is no clear evidence for extraterrestrial life. This paradox was named after physicist Enrico Fermi, who made the point that we hadn’t seen any extraterrestrials. Where is everybody else? The Fermi paradox has possible solutions that are split into 3 categories: we are alone; civilizations are common, but no one has colonized the galaxy; and galactic civilizations exist, but it has not been revealed to us yet.
The first solution is the scariest to me; I hate the idea that we are truly alone. It would make for our society to be an extreme accomplishment, but it would also make for a tragic future when our civilization collapses.
The second solution is also scary because it indicates less hope in our civilization achieving interstellar travel. What happened to other civilizations may happen to ours’. What does this mean for us?
The third solution is the most hopeful. This is also, personally, the solution is believe the most in. The universe is too vast and untravelled for there to only be us existing.
If climate change is a generic process that affects all highly developed civilizations, it could be one of the most compelling explanations of the Fermi Paradox
Broadly speaking, our views on the probability of extraterrestrial life have gotten more optimistic over time due to a long series of discoveries that have increased our estimates for the size of the universe, the frequency of planets, the frequency of liquid water on worlds, and the ability for life to thrive in extreme conditions. This only makes the Fermi paradox more paradoxical— where are all the aliens?
Our textbook groups solutions into three major categories: we are alone, civilizations exist but have not colonized the galaxy, and existing civilizations have not revealed themselves to us. I find category two to be the most compelling. It is hard for me to believe that there are no alien civilizations out there, and I find explanation three to be conspiratorial and far-fetched. I imagine that it is difficult for civilizations to last long enough to achieve interstellar capabilities, due to natural and self-inflicted processes.
As the Wikipedia article for the Fermi paradox states, many natural extinction events have occurred on Earth, caused by volcanic eruptions, giant impacts, and maybe even gamma ray bursts. Although these events have been relatively infrequent on Earth, it would take far less than an existential-level threat to wipe out or significantly set back an otherwise “galactic” civilization. Perhaps this magnitude of natural event is frequent enough to limit the lifespans of galactic civilizations enough to prevent them from realizing their potential.
It is also possible that civilizations destroy themselves before they can colonize the Galaxy. Once a civilization discovers nuclear weapons—which is nearly if not necessarily a prerequisite for galactic capabilities—the odds of self-inflicted extinction rise several orders of magnitude. Combining both natural and self-inflicted processes, climate change is a particularly interesting aspect of this issue. A 2018 interview with astrophysicist Adam Frank explores the process of climate change as a symptom of the Anthropocene transition and views both through an astrobiological lens. Frank posits that perhaps every technologically developed, energy-dependent civilization drives significant change in their planet and its climate. While his initial theories did find steady states, where a civilization does not destroy its planet and itself, there is a real possibility that a galactic level civilization places a very restrictive time limit on itself through self-inflicted climate change and planetary transition.
As we progress through our own Anthropocene transition, we will undoubtedly learn more about potential lifespans for intelligent civilizations. Hopefully, humanity achieves one of Frank’s steady states and lasts long enough to make contact with other forms of life.
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Infrastructure is everywhere. Most every way of transport that we consider using regularly has immense infrastructure. Cars have roads, trains have rails and stations, and airplanes have airports and runways. But with space travel, we take the brute force method, spending immense amounts of money and forcing a rocket to defy gravity and get itself into orbit. Organizations like SpaceX are currently trying to remedy some of the issues with this, with reusable rockets and other new technologies, but there is one technology that could massively accelerate the feasibility of space travel, the Skyhook
The Skyhook is a simple mechanism, basically consisting of a cable and a counterweight, placed in orbit. The concept of its use is as follows. A spacecraft would have to reach a height of 80-150 km by itself in order to attach to the Skyhook cable, and then the rotational force of the Skyhook would swing the spacecraft into space like a catapult, as shown below.
Of course like any technology there are hurdles to overcome, even though 150 km is much easier to reach than breaking a low orbit of say 1000 km, that is still quite a height to get to, and would require the invention of a new craft that is something of an airplane rocket hybrid. However, it still should be much cheaper, especially if these craft are reusable. Additionally, the Skyhook would not be able to be used permanently because every time it flings a spacecraft into space it would lose a little bit of altitude itself. There are many other potential obstacles, but in my opinion, none that are improbable or outweigh the potential benefits of eliminating the modern wasteful rocket.
The universe is magnificently huge, and hence should have countless opportunities for life to develop, but that then begs the question, where are all the aliens? Due to the expansion of the universe being faster than the speed of life, there may be life throughout many galaxies, or even most of them, but we would simply never really know for sure do to any signal sent being outpaced in speed by the expansion of the universe, at least with our current understanding of physics. So it is practically pointless to search for life outside of our galaxy, so then where are all the Milky Way aliens? Even narrowing our search area to just 1 of 100 billion galaxies, there still should be ample opportunities for life to develop in our galaxy, where communication, however still improbable, is possible. Different studies estimate there are anywhere between 300 million to 6 billion Earth-like habitable planets in the milky way, so what gives?
There are many theories as to why life seems to be missing from the Milky Way. Perhaps they are in hiding, and only the silent civilizations survive. Perhaps they have all died out, and we simply live in a time where no other near type 1 or type 2 civilizations exist alongside is. Perhaps we are the first, pioneering the concept of intelligent life. Or perhaps billions of chances for life simply is not that many if we truly knew how complicated and rare life developing is, and we sincerely are special in this galaxy. Only time and technology will tell.
A man named Andy Weir, created an idea of life and the universe called, The Egg. The story starts out with a man dying in a car crash and coming face to face with what seems to be God. Immediately this person begins asking about their family and the life they left behind along with what happens next. The large being before him tells him not to worry and that he is going to be reincarnated as a girl from 540 AD. Puzzled the man does not understand how he can become someone from the past, someone that must have already existed if he lived past that date. The being explains that time is merely a physical concept. The man then ponders if he could have been reincarnated at a time when another version of himself was living. The being nods and says that this is true. Finally, the being explains that the whole universe was made to be a growing and maturing experience for the man and he will be and has been every person who has ever existed. He learns and grows through interacting with himself as every person is a version of himself. This universe is essentially, an egg, a place for this being to grow to become like the larger being and one day be what we consider a God. Some see this as a real theory of life! While others just think it is a nice way to say we are all connected and all of our actions affect others in ways that ultimately affect ourselves.
The Fermi Paradox attempts to describe why we have not made contact/found any intelligent life although the conservative estimate for how many intelligent civilizations there are throughout the universe is ten million billion. This theory is completely based on speculative math using the data we know about our universe. The paradox also describes Types of intelligent civilizations such as Type I (able to harness all the power of their planet; we are considered 0.7 of the way there), Type II (able to harness all of the power of their host star), Type III (able to harness all of the power of their galaxy). Due to how many intelligent civilizations there should be many of them would most likely be much older than us with an older star and would therefore be at one of these later stages. This then leads many to believe that the theory that none have reached out to us yet wouldn’t hold with the amount of individual civilizations there are that could reach out. This conclusion points many to the idea of the Great Filter.
The Great Filter: The idea that at some point between the beginning of its life and and Type III (when it could make contact with Earth) all intelligent civilizations hit a wall, or some stage in its evolutionary process that is near impossible to overcome. The Great Filter suggests either one of a few things. We could be rare meaning The Great Filter is behind us and occurred already. Whatever this may be must be a one-billion chance event. This leads to the Rare Earth Hypothesis that maybe the conditions of Earth and exact formation was truly the only way to create life.
Others think we are the first civilization and the conditions of the universe are optimal for the first time since the big bang for life to exist.
Another possibility is the Great Filter is ahead of us. This would civilizations commonly get to our stage in evolution but something eventually prevents it from growing. This could be a natural event such as a Gamma Ray burst or even the notion that once a civilization reaches a certain level of technology nearly all of them end up destroying themselves.
Another group think there are reasonable explanations for why we haven’t discovered Type II and III civilizations but that they exist. One explanation is that they have visited Earth but just so long ago there were not records and our lifetime as a civilization is not long enough yet to have experienced it again. Our galaxy may also have been colonized but we live in a very rural part of it and mostly desolate. Once Type II civilizations achieve the use of their star they have no need or desire to reach out to other civilizations that are more primitive. Another, really cool albeit terrifying explanation, is there are predator civilizations out there and most intelligent life knows better than to broadcast their existence and location. Similarly, there may be one super-predator that keeps killing off all the other civilizations. Higher civilizations may also be observing us or even kept from us by the government (conspiracy theorists maybe you deserve an apology:)! Higher civilizations may also be all around us but we’re to primitive to see them or understand what they’re doing. Finally (for now), we may just be completely wrong about our entire reality!
Overall, the Fermi paradox attempts to explain the fact that math points to there being ten million billion other intelligent civilizations and yet we have heard from none and have found no other life. Why?
The golden record is a collection of songs, messages, and symbols placed on a golden disk that was sent out on the voyager spacecrafts. The record also has imprinted on it a small encoded map about where Earth is or how far away it is, as well as messages telling whatever species that obtains this record on how to play it.
However, it should be noted that these sounds and records come from the 1977, an older version of America. Since then, our technology and capabilities as a species has increased exponentially. This record has no information on how the world is today, with the increasing use of the internet, the updates to human society, and how much more capable we are at sending messages across space. If an alien race found our golden disk, they might only assume that we humans are still at that level of technology and we cannot produce anything more advanced.
It would be a funny concept, if an alien civilization came to Earth expecting the same world as the 1970s only to be introduced to a Gen Z world with TikTok and iPhones. Furthermore, if we ever receive first contact, we should treat it as a lowball of how advanced the alien civilization is. Maybe for future probes going deep into space, more updated disks will be sent showing how far we have come.
Megatron holding the Golden Record. Don’t ask me how I know this, I just do. Source from ScreenRant.
Drake Equation, as well as all of the factors that go into it. Credit goes to Business Insider.
The Drake Equation is an equation used to determine the odds of communicating with another alien civilization. Created by Frank Drake in the 1961, it was a product of all of the odds of life forming, planets having suitable habitats, and how successful the life was on the planet.
The first value was R, or how many sun like stars are in the Milky Way Galaxy that can have. The next following values are the odds of how many of these stars have planetary systems (fp) and how many of these planets are in the habitable zone of the star (ne). Fp is always high because evidence shows that the majority of stars develop planets from their accretion disks. Ne, however, has a higher range due to the situations of a terrestrial planet being in the habitable zone or a large gas giant with multiple terrestrial moons in the habitable zone. These two values could be estimated by looking at other systems and understanding planetary formation.
The other variables are much harder to accurately range. The odds of life developing, intelligent life developing, and such life developing communication technology are highly speculative. There is only one sample that we can use as reference for this one; Earth. Out of all planets, bodies, and systems that we have observed, Earth is the only planet that us humans have discovered life on.
Although this could be due to pessimistic bias, but the odds of life forming is fairly small, since scientists have failed to create life even under ideal circumstances. The results may improve through time, but it appears to be a random chance occurrence rather than an eventuality. For such life to become intelligent, there needs to be enough competition in the ecosystem to force evolution to evolve sentience. This took Earth 3.7 billion years, and the odds of life randomly going extinct also make this value smaller. Finally, there is the odds of such life developing communication. There is no inherit need for a species to look to the stars apart from curiosity and looking for more resources, and the odds the alien species thinks like us is very slim.
The final variable is L. This is how long a civilization can exist without self imploding or losing to natural causes. This is probably the lowest. A competitive alien species would develop weapons in order to survive and adapt. Us humans have always been inventing new weapons to give us a new edge against ourselves. We developed nuclear bombs at around the same time as we sent out the first radar signals. We used said nuclear bombs before we ever set a man on the moon, and we have had multiple wars since. It is my unfortunate conclusion that an advanced alien race would also face these issues and go extinct quickly.
Due to all of these low percentages, the odds of communicating with life is slim to none, and this is for the whole Milky Way, not just some nearby star system. As pessimistic as this seems, it also is quite special, since it shows despite these low odds, we as humans are somehow here. We managed to beat the odds, and our mere existence is something of a miracle.
Figure 1. Skyhook concept where a space shuttle is attached to a satellite in orbit (via tether) and is hurled away from Earth.
One of the biggest issues with rocket launches today is the inefficiency of converting fuel into thrust. Because of this, rocket payloads have to be small compared to the amount of space required for fuel. For instance, the SpaceX Falcon Heavy rocket carries a total weight of fuel of ~411 tonnes (the equivalent weight of 2.5 average-sized American homes). Clearly, we must look at alternative methods of guiding a rocket into space and away from Earth while allowing for more space for a payload.
Enter the concept of a “skyhook”. The idea behind a skyhook is to have a satellite with two attached tethers: one long tether with a hook that can attach to an incoming spacecraft and another short hook with a counterweight. As shown in Figure 2, if one can get the satellite’s orbital velocity to synchronize with the tether rotation rate, then the tether’s tip will move as a cycloid curve. There are two key characteristics of a cycloid curve that will help us understand the idea behind a skyhook. First, when the tether reaches its lowest point, it is essentially stationary. Here, an incoming spacecraft can safely attach to the skyhook. Second, at the tether’s highest point, the velocities of the satellite and tether are working in the same direction. This means that this point serves as the location at which the skyhook is traveling at its fastest speed. Thus, releasing the spacecraft here would allow it to slingshot away from Earth at high speeds.
Figure 2. An example of a cycloid curve for a rotational system.
So, what would be a concern of utilizing such a system? Skyhooks are also referred to as “Momentum Exchange Tethers”. This is because the rotational momentum from the satellite is transferred into the attached spacecraft as the spacecraft is accelerated. Over time, if rotational momentum is not added back into the satellite-tether system, the system would eventually stop spinning. To prevent this, the skyhook would either have to have on-board thrusters that could burn for a specific amount of time (allowing the system to regain rotational momentum), or the skyhook would have to be capable of slowing incoming spacecraft down for a descent to Earth. The latter option means that the momentum from the fast-traveling spacecraft would be added to the satellite-tether system.
If we are able to successfully design, construct, and deploy these skyhook systems, a great amount of money and space on rockets can be conserved as the required amount of fuel to complete a space mission would decrease. This would also open the doors to incorporating skyhooks across the Solar System (i.e., around the Moon, around Mars, etc.). Accomplishing such a feat would allow for a more constant stream of rocket launches to occur.
