We know that astronomers look to low-mass star systems for signs of life. But new research from NASA has indicated that these low-mass stars may emit substantial amounts of ultraviolet radiation during their lifetime, hindering if not eliminating the possibility of life on orbiting planets. Of course, astronomers look at terrestrial worlds that lie in the habitable zone, which means where liquid water can flow on the planet’s surface.
M-Dwarf stars, the most common type of star in our galaxy, are sufficiently small and cool such that orbiting planets come very close to the star during transit, allowing for easier detection here on Earth.
Astrophysicists Adam Schneider and Evgenya Shkolnik published recently a paper that held that the hottest and most massive M-Dwarf stars, called “Early Type,” emit higher levels of potentially harmful ultraviolet radiation during their lifetime compared to other M-Dwarfs. The abundance of UV rays can erode planetary atmospheres, strike down the molecules in planetary atmospheres, and make it extremely difficult for life to survive.
We know that astronomers look to low-mass star systems for signs of life. But new research from NASA has indicated that these low-mass stars may emit substantial amounts of ultraviolet radiation during their lifetime, hindering if not eliminating the possibility of life on orbiting planets. Of course, astronomers look at terrestrial worlds that lie in the habitable zone, which means where liquid water can flow on the planet’s surface.
M-Dwarf stars, the most common type of star in our galaxy, are sufficiently small and cool such that orbiting planets come very close to the star during transit, allowing for easier detection here on Earth.
Astrophysicists Adam Schneider and Evgenya Shkolnik published recently a paper that held that the hottest and most massive M-Dwarf stars, called “Early Type,” emit higher levels of potentially harmful ultraviolet radiation during their lifetime compared to other M-Dwarfs. The abundance of UV rays can erode planetary atmospheres, strike down the molecules in planetary atmospheres, and make it extremely difficult for life to survive.
Here they are pictured, in it it’s glory, and the young supermassive black hole at the center actually sucks in huge amounts of gas and dust that shine brightly as the material is funneled. Matter can escape the black hole though, and these bubbles are a huge outflow.
Gravitational Singularity, or spacetime singularity, is a point with infinitely small size and infinitely big density, gravitational force and time curvature. At that point, no physicals laws we know right now can be applied. According to the big bang theory, our universe is expanded from a universe singularity.
According to current theory, when an object falls into the blackhole and approaches to the central singularity of the blackhole, the object will be flattened and elongated because of the larger gravitational force. As it will be longer and longer, the object will finally lose its dimension and disappears at the singularity. Besides, some mathematical inductions state that materials in three dimension world will be destroyed by the singularity and lose its third dimension. Instead it will exist in the blackhole in the form of two-dimensional object, while its two-dimensional data can be restored as three-dimensional object. Therefore, some scientists believe that our world is actually a two-dimensional world, and the third dimension is actually a projection of the two-dimensional data.
Because of the nature of singularity, it is possible that we will never be able to describe singularity with full detail. Nor will we truly understand the singularity in the center of the blackhole. Even though spectator might be able to send signal into blackhole, the spectator might never get any response back. Therefore, we can only induce that singularity do exist by theorems, while we are lack of any data to provide its existence.
My appreciation for astronomy and astrological theorization and examination has increased significantly throughout this course. From the periphery, astronomy seems overwhelmingly complex and unimaginable. But, when you venture into the weeds and examine closely, it is remarkably intuitive and fundamental. Still, certain phenomena have yielded contradictory conclusions that befuddle some of the brightest of minds. One such phenomenon is the Olber paradox.
The Olber paradox discusses why the sky is dark at night. It postulates that if the universe is infinite and constant, the night sky should not be dark, and be bright because every line of sight into space should be looking at some star in the universe and so the sum of all this light should make the universe uniformly bright. The resolution to this paradox states that the universe is either finite or it is changing (thereby negating one of the initial assumptions of the paradox). Specifically, if the universe had a beginning then we can only see a finite, fixed number of stars which lie in our cosmological horizon. Thus, we have a dark night sky.
As this paradox demonstrates, there are elements of space, the universe, and life that the human mind and its construction of a cause-and-effect frame of analysis cannot quite grasp without sacrificing or negating certain assumptions. As a result, we do our best to theorize and explain the untestable.
My appreciation for astronomy and astrological theorization and examination has increased significantly throughout this course. From the periphery, astronomy seems overwhelmingly complex and unimaginable. But, when you venture into the weeds and examine closely, it is remarkably intuitive and fundamental. Still, certain phenomena have yielded contradictory conclusions that befuddle some of the brightest of minds. One such phenomenon is the Olber paradox.
The Olber paradox discusses why the sky is dark at night. It postulates that if the universe is infinite and constant, the night sky should not be dark, and be bright because every line of sight into space should be looking at some star in the universe and so the sum of all this light should make the universe uniformly bright. The resolution to this paradox states that the universe is either finite or it is changing (thereby negating one of the initial assumptions of the paradox). Specifically, if the universe had a beginning then we can only see a finite, fixed number of stars which lie in our cosmological horizon. Thus, we have a dark night sky.
As this paradox demonstrates, there are elements of space, the universe, and life that the human mind and its construction of a cause-and-effect frame of analysis cannot quite grasp without sacrificing or negating certain assumptions. As a result, we do our best to theorize and explain the untestable.
Incredibly species of microorganism and microbes have tested the limits of evolutionary theory as they have been discovered to survive an incredible range of extreme conditions. These microbes, called extremophiles can survive in various extremes: incredibly high temperatures, near-vacuum condition of space, and in the freezing cold. In fact, scientists have discovered microbes within the freezing cold, dry valleys of Antarctica. These microbes actually live inside rocks, surviving on tiny droplets of water and energy from sunlight.
Perhaps the most famous extremophile, tardigrades or water bears, have been discovered in Antarctic lakes, so deep beneath the ice that they have not been exposed to open air or sunlight for millions of years! Extremophiles have discovered to not only survive, but in fact thrive in environments so acidic, alkaline, salty or with such high radiation that it would kill humans instantly.
A picture of a tarigrade (also called a ‘water bear’), sourced from sparticl
Scientists have been able to use information from these extremophiles to outline three basic requirements for life. First, an organism must have a source of nutrients from which to build living cells. Second, it must have access to energy to fuel the activities of life. This energy can come from the sun, chemical reactions, or geological heat. Lastly, life must have liquid water. Synthesizing the information gathered from the analysis of extremophiles, scientists have simplified the necessities for life and discovered how organisms can survive in extreme conditions that were previously thought as incompatible to life.
Incredibly species of microorganism and microbes have tested the limits of evolutionary theory as they have been discovered to survive an incredible range of extreme conditions. These microbes, called extremophiles can survive in various extremes: incredibly high temperatures, near-vacuum condition of space, and in the freezing cold. In fact, scientists have discovered microbes within the freezing cold, dry valleys of Antarctica. These microbes actually live inside rocks, surviving on tiny droplets of water and energy from sunlight.
Perhaps the most famous extremophile, tardigrades or water bears, have been discovered in Antarctic lakes, so deep beneath the ice that they have not been exposed to open air or sunlight for millions of years! Extremophiles have discovered to not only survive, but in fact thrive in environments so acidic, alkaline, salty or with such high radiation that it would kill humans instantly.
A picture of a tarigrade (also called a ‘water bear’), sourced from sparticl
Scientists have been able to use information from these extremophiles to outline three basic requirements for life. First, an organism must have a source of nutrients from which to build living cells. Second, it must have access to energy to fuel the activities of life. This energy can come from the sun, chemical reactions, or geological heat. Lastly, life must have liquid water. Synthesizing the information gathered from the analysis of extremophiles, scientists have simplified the necessities for life and discovered how organisms can survive in extreme conditions that were previously thought as incompatible to life.
If you are interested in aliens and Fermi paradox, there is a must-read novel “The three-body problem”.
The novel was written by a Chinese writer Liu Cixin, and in the novel Liu introduced a theory called “The Dark Forest Theory”. The theory has two axioms. The first one is that “survival” is the first need of a civilization, which means each will do whatever it can do to ensure it is able to survive. And the second axiom is that the civilizations will always grow, develop and expand, needing more and more resources, while the total amount of resource in the universe is finite.
Liu then introduced a concept called suspicion chain. If two civilizations meet each other, they would like to know if the other side is “friend” or “enemy”. Even though the other side behaves friendly, they would not know for sure if the other side is genuinely friendly or just faking. Therefore, the bottom line is every civilization other than us is a potential threat, and the best way for our civilization to survive is to hide ourselves and destroy any potential threat we could find (without revealing ourselves).
The theory farther refers the universe as a dark forest, while each civilization is a hunter inside it. Each hunter should be extremely careful since there are a lot of hunters like him in this forest, and when he find another people in the forest, he should kill them as quick and insidious as possible.
As Fermi paradox is the apparent contradiction between the high possibility estimates for the aliens and the lack of existence of aliens, the dark forest theory might be a possible response as it states that all the civilizations will try to protect themselves by not revealing themselves for the outer world.
For my last blog post for ASTR 2110, I wanted to discuss a topic that I think is really cool; computers made specifically for space. Learning about these systems is what inspired me to pursue computer engineering in grad school, so I hope to communicate how awesome these systems are.
During the space race, the budding electronics industry helped make the feats of engineering possible. Through government funding, labs like IBM and the Charles Stark Draper Lab at MIT were presented with the unique challenge of creating computer systems that would function in a variety of space scenarios.
The Apollo missions were especially difficult due to their lunar maneuvers, but the various labs rose to the challenge. Not only did these computer systems need to navigate and guide the spacecraft to the Moon, but they also needed to facilitate takeoff from the Moon, the rendezvous with the various Lunar vehicle modules. not to mention be redundant enough to withstand system failures.
The device pictured above was MIT Instrumentation Laboratory’s solution to such a complex problem. With 1/70th the computing power of the Motorola RAZR, the Apollo Guidance Computer (AGC) successfully provided guidance, navigation, and control to the Command and Lunar Modules in the Apollo program.
The AGC was one of the first integrated circuit-based computers. This means that there was very little modularity – the way it was constructed was the way it flew. The designers at MIT had very little margin of error, but after only producing two errors during flight, both of which were previously known and well documented, I’d call their work a huge success. The AGC would go on to influence the designs of the computer systems of Skylab, the Space Shuttles, and other early fighter aircraft systems (the software itself is on github)
To interface with the AGC, the astronauts would use the display and keyboard, or the DSKY. Instead of having 101 keys like most modern keyboards, it only had 19. Commands were input using a 2-digit format, a verb and noun. The crew had only 99 verbs and 99 nouns to carry out all the complex tasks of guidance and navigation of a spacecraft. For example, displaying the spacecraft altitude was accomplished by entering Verb 16 Noun 20. I found a DKSY simulator if you’re interested in trying out other commands
The feats that engineers were able to accomplish with such limited technology was nothing less that astounding. With components that are less have less than a millionth of the computing power of today’s smartphones, we were able to travel to the Moon and back safely and efficiently. I’m excited to one day be a part of this legacy.
