Wen 丨 Silicon Valley 101 (ID: svstyle), Interview 丨 Hongjun, Text 丨 Li Wanchen, Editor 丨 Hu Shaoyang
In the early morning of January 25, after a month of space travel, the largest and most expensive space telescope in human history, James Webb, finally arrived at Lagland l2, 1.5 million kilometers from The Earth, and is about to start scientific research.
Figure | JWST reaches final orbit Source: NASA GSFC/CIL/Adriana Manrique Gutierrez
If the plan is successful, the Weber Space Telescope will probe the signals of the universe's first-generation celestial bodies, studying the various properties and evolutionary relationships of galaxies at different times in the universe. Solve many mysteries about space and even reveal the origin of the universe for us.
The space telescope is the largest astronomical project ever built by mankind: $10 billion, more than 20 years of research and development, and the cooperation of 14 countries around the world. It can be said that many people have spent their entire careers building the Webb Space Telescope.
The solar sail was torn apart, the screws disappeared during the vacuum experiment, and the development process of the Webb telescope was full of uncertainty and was almost cut by Congress in 2011 due to multiple delays.
NASA says it faces the possibility of 344 single-point failures in the six months between launch and when it actually begins work. The New York Times even joked during the launch: "What were the astronomers eating for breakfast before Webb launched?" The answer is their fingernails. ”
The challenge to the limit will also be accompanied by unexpected gains, a new refrigeration technology, invented in the development process of the Weber Space Telescope, as long as Weber can normally receive electrical energy through the solar wind, ideally the working life can reach 10 years. And according to recent NASA estimates, it is likely to be in service for 20 years beyond normal.
Hong Jun, anchor of this issue of "Silicon Valley 101", and Long Feng, postdoctoral fellow of harvard-Smithsonian Center for Astrophysics, talked to Lu Jianwei, ph.D. in astronomy and astrophysics at the University of Arizona and member of the James Webb Science Team, to talk about the historical heritage of the outer astronomical telescope and the challenges that the James Webb Space Telescope will face.
(For a question on whether the starlink affected Weber's work, see our last report, "Locking Up Ground-Based Astronomical Observations, Why Are Musk's Starlinks Hated by Astronomers?") 》）
01 James Webb: Bigger, more expensive, stronger space telescopes
Silicon Valley 101: Jianwei is now part of the James Webb team, can you tell you what you are involved in?
Lu Jianwei: I am currently in the James Webb Science Project Group in the Department of Astronomy at the University of Arizona, working on postdoctoral research.
Usually, my research direction is to study the characteristics of supermassive black holes and various galaxies in the universe through the infrared band. I myself have been involved in several James Webb observation projects. The target of observation extends from the black hole at the center of our Milky Way to the most distant quasar in the universe. So we will conduct some systematic research on various celestial bodies of different ages in the universe.
Recently, I was preparing for some of James Webb's formal observations, including data simulations, tool development, and background science research. James Webb is the largest astronomy project ever built by mankind, costing more than $10 billion.
Photo | James Webb Space Telescope Source: NASA
Weber's caliber is about 6.5 meters, and the mirror surface is made up of 18 small mirrors. It is a telescope in the infrared band. It was just launched last Christmas and is currently on its way to its final destination, Lagrange L2. This point is about 1.5 million kilometers from Earth, about 3 times farther than the Moon.
Silicon Valley 101: Why does it have such significance in space? What problems can it solve after it goes up?
Lv Jianwei: First of all, it is much larger than all the previous space telescopes. In addition, it works in the infrared band, which is particularly suitable for some scientific research on the origin of the universe and the origin of life.
According to NASA, there are four major scientific goals.
The first goal is to detect signals from the universe's first-generation objects. Signals from the first generation of stars, galaxies, and active black holes at the end of the Big Bang.
The second goal is to limit the birth and evolution of galaxies. It is mainly to study the various characteristics and evolutionary relationships of galaxies at different times in the universe.
The third goal is to explore some stars, as well as the birth of the surrounding primordial galactic disk. This is also an area where space telescopes could not observe or were not restricted enough.
The final one is that telescopes can also observe planets in the solar system, including Jupiter, Saturn, Uranus, Neptune, and so on. It can also observe planets in surrounding stars outside the solar system. There are many stars in the Milky Way, and there will be systems like the Solar System around the stars.
Scientists are very interested in the various properties of the planets in these system of extrasolar galaxies. People wonder if there's any atmosphere, or life, on the planets there. This is a very exciting topic.
Long Feng: This aspect is also the focus of my work. The direction of my work is probably to explore why different kinds of planetary systems can form, and why they are different from our solar system. James Webb will make remarkable achievements in this regard.
I would like to ask Jianwei, can you introduce the development of infrared astronomy in the past few decades? Why let it go to heaven, there will be such a prominent effect? Why can't we achieve this with ground-based telescopes or other means?
Lv Jianwei: The development of infrared astronomy is a very large topic, probably several centuries of history, and I can only start with the simplest content.
Why put infrared telescopes in space instead of building them on Earth? This is because it is particularly difficult to observe infrared directly from Earth. The Earth's atmosphere itself has very strong infrared radiation. The sky on the ground, day and night, has always been bright. The infrared wave terminal remains very bright, and it is difficult to identify weak celestial signals.
This does not depend on the presence or absence of the sun, the atmosphere itself has been radiating. You look at the sky during the day and night, and if you're in the infrared band, it's always bright as it was during the day. Searching for infrared signals from distant objects in this environment is very difficult. So you can't do it on the ground.
Long Feng: I want to use the Hubble analogy. Hubble is in a low-Earth orbit, and Webb will be much farther away from Hubble's orbit this time at L2. Is the infrared radiation of the Earth's atmosphere the main reason why we want to put the Webb telescope so far?
Lv Jianwei: Yes. James Webb needs to be very sensitive in the infrared band, so have a very cold environment. The operating point it will eventually reach, Lagrange L2's ambient temperature is minus 223 degrees, and the surrounding material is also very thin, so the infrared radiation in the surrounding environment itself is very low.
The scientific observations that James Webb needed were not enough to just put the telescope there. The Earth's atmosphere has infrared radiation, and a very bright Earth and sun can be seen at the infrared wave end.
So James Webb made a very large solar visor. It is both a solar cell and a sun visor, with five layers. The presence of a sun visor guarantees that the telescope, and all its instruments, will never be illuminated by the sun or the Earth.
Photo | large solar visor of a tennis court Source: NASA/Chris Gunn
It has a very low temperature with its back to the side of the sun that is blocked by the sun visor. Its temperature is only about minus 234 degrees Celsius, which is about 40 degrees above absolute zero. It has an instrument called MIRI that operates at temperatures as low as 7 k, or minus 266 degrees Celsius. The team used very advanced technology to ensure that it could always work normally at this low temperature.
Compared with the Hubble Space Telescope, because Hubble mainly operates in the ultraviolet to near-infrared bands, it is not very sensitive to temperature or infrared radiation from the Earth's atmosphere and surrounding celestial bodies. It can also perform some normal operation in low Earth orbit.
But if you want to work to longer wavelengths, James Webb's wavelength is much longer than Hubble's. Hubble's longest wavelength is 2.5 microns, but James Webb's longest wavelength is 28 microns, more than 10 times, so it's placed fairly far from Earth.
Figure | Hubble vs. Weber Band Differences Source: NASA and J. Olmstead
Silicon Valley 101: Let me summarize briefly, the reason why we put the telescope in space is to avoid interference in the infrared band on Earth. Hubble's observation range can be said to be visible light plus some infrared band of invisible light. But James Weber's observation range includes all-infrared wavelengths.
Lv Jianwei: Yes, so to speak. It optics also has a little bit to shoot, but not the main function.
Silicon Valley 101: Hubble has made many important contributions to astronomy. Can you briefly introduce what is its important contribution to astronomy? Why is it that putting a telescope in space will make so many scientists very excited? What exactly can it do?
Lu Jianwei: The Hubble Space Telescope has made so many scientific discoveries that it is difficult to pick out one of the most important contributions that everyone recognizes as unanimous. But I personally think the most well-known is the "Hubble Extreme Deep Field" of this area. During the nearly 30 years of its operation, Hubble made repeated, multi-band observations at a specific location in the sky, reaching an exposure time of 22 days. That is, the telescope stared motionless at that point for 22 days, collecting signals from the distant starlight of the universe in that direction.
Figure | Hubble Extreme Deep Field Source: NASA
It found more than ten thousand distant galaxies in that tiny area. The current age of the universe is 13.8 billion years. Hubble saw the signals of galaxies between the ages of 5 and 600 million in the universe through the extremely deep field. This is the most distant starlight signal in the universe that humans have seen so far. This is the limit of humanity at present.
Hubble is relatively small and has a blue band of operation, not especially where infrared wavelengths are long. So he has few restrictions on the earliest galaxies, only to vaguely see some spots, and the specific properties are not clear.
Silicon Valley 101: Can we understand that if we want to explore the origin of the universe, using hubble telescope is equivalent to seeing pictures of the universe in the juvenile period of star and planet formation; but with James Webb, we can see pictures of earlier infancy.
Lu Jianwei: Yes, the limit of Hubble's current detection is the galaxy that is 500 to 600 million years old, and James Webb can roughly see the signal of galaxies or other stars when the universe is 100 to 200 million years old. Did there exist galaxies or stars during this cosmic period? What are their properties if they exist? Nobody knows. A lot of speculation requires us to observe with James Webb.
"Silicon Valley 101": After the photos are taken, it may be the main thing that Long Feng mainly studies. Equivalent to Jianwei building a telescope in front, Long Feng expects the photos sent back by the telescope to help expand research.
Long Feng: Maybe we both use photos for scientific research. Hubble has also done a lot of electronic work on my own research direction. My direction is roughly to study how planets form.
Several of the planets in the solar system orbit the Sun on almost the same plane. We can assume that the process of planet formation is done in a very thin disc-shaped plane. This hypothesis was confirmed by photographs sent back by Hubble 20 years ago. It helps us understand that this structure is so widespread that the process of galaxy formation is everywhere. In this way we have discovered so many exoplanets.
On this basis, Weber will do a more detailed analysis of these disk structures, doing a lot of detailed analysis of the atmospheres of known planets, and analyzing the structural components of the structure, to explore whether there are molecules related to life.
Silicon Valley 101: I've seen a popular science documentary before. He proposed to study human life, not from the time dimension of human infant to child to old age. The universe is so old that if we take a large enough picture with enough samples, we can study its multiple ages at the same time to see how the planet evolved.
Long Feng: Yes, so we need our equipment to be strong enough and our light collection ability to be good enough to see more distant places. That was when it was much earlier, with larger samples that could be observed simultaneously around the clock, in different wavelength bands, to ensure that enough samples were available for statistical analysis.
"Silicon Valley 101": More and larger samples can be taken.
Dragon Phoenix: Yes, and more detailed information, it is much larger than Hubble.
Lu Jianwei: I would like to add that James Webb has a big advantage in the formation of early stars or galaxy disks around stars. Its observation wavelength is longer, so it can see some systems that are colder and have a lot of dust around it. This corresponds to the time when very early stars or disks of surrounding galaxies formed.
02 Innovative refrigeration technology or let Weber work for extra long
Silicon Valley 101: There was actually an infrared space telescope Spitzer before James Webb. It is relatively similar to James Webb's band, and there is a lot of technical inheritance.
Photo | Spitzer Source: NASA
Can you tell us what Spitzer is? What did James Webb technically inherit from Spitzer?
Lv Jianwei: Spitzer is very close to our school, and the two husband and wife astronomers in our infrared group were also responsible for his key instruments in the Spitzer era. Many people say that James Webb is the successor of Hubble, but it can also be said that it is also the successor of Spitzer.
Spitzer is closer to James Webb in addition to the working band, and the ups and downs in history are also similar. James Weber began conceiving in the early 1990s, designing and manufacturing around '97, and today he probably spends less than 25 years. The Spitzer telescope was conceived in the early 1980s and took about 20 years to successfully launch. In the middle, they encountered many, many technical difficulties, including insufficient funding from NASA, or accidents.
The U.S. space shuttle Challenger exploded in 1986 before it entered orbit. Hubble also had a problem in 1991, when it was found that the mirror was inconsistent with the design and had a "myopia" problem. A series of accidents have led the United States to re-examine the space program. Both Spitzer and James Webb were nearly cut due to over-budgeting, but thanks to the persistence of a small number of scientists, the final launch was achieved.
Regarding the relationship between the two, the Spitzer telescope is much smaller than James Webb. Its caliber is less than 1/8 of that of James Weber. Its revolutionary technology lies in "passive refrigeration".
All objects have infrared radiation, including the earth's atmosphere, the telescope itself (mirror, detector, electronic circuit), etc. The temperature of the entire system needs to be lowered for better infrared detection evolution. Before Spitzer, it was common practice to install the entire telescope in a large cylinder surrounded by liquid nitrogen, and then throw it into the sky by rocket, and most of the fuel carried was to push the large cylinder. Because the Spitzer telescope was at risk of being cut down in the 1990s, people tried to improve quality and reduce costs.
One day an astronomer at our school came up with a method. Instead of putting the telescope in liquid nitrogen, we can throw the telescope into space and use the environment to automatically cool it. People only need to use some substances with high heat dissipation coefficients in the design materials, and then wrap the electronic circuits around the detector in a smaller liquid nitrogen tank. In this way, the overall launch cost is much lower, and the telescope can be made larger, which is a technological innovation.
Then this technology was fully applied to James Webb, and at the same time, James Webb proposed a new technology in this regard.
Before everyone needed to bring liquid nitrogen to heaven, and use its sublimation to take away the thermal energy of the surrounding substances, which was a consumable. Therefore, if the previous infrared telescope had to be refrigerated, it could only consume the liquid nitrogen it carried in two or five years, and then it was not so sensitive in the infrared band.
James Webb invented a refrigeration technology, similar to an ultra-small refrigerator. It provides electrical energy, compresses the refrigeration substance inside, and then conducts it into the equipment to sublimate the heat absorption. It is a circulatory system that, in principle, does not consume any refrigerant. As long as James Webb can receive electricity through the solar wind normally and provide electricity to the "refrigerator", the telescope can always work on the infrared wave.
Silicon Valley 101: How long can the James Webb telescope work?
Lv Jianwei: According to the original design, the minimum indicator of this telescope is 5 years of operation, and ideally it can reach 10 years. But recent nasa estimates suggested it could work for 20 years. The most limited time it can run is how long the fuel you carry with you can use. When it reached Lagrange L2, it was not completely motionless. It will be hit by the solar wind and hit by tiny celestial bodies, so the attitude needs to be adjusted. It requires the use of fuel and propellant to adjust the attitude, but the fuel it can carry is limited.
The reason why it is now expected to run for 20 years is because it has a precise orbit when launched, smooth correction when it reaches L2 point, and does not consume excess fuel, so basically all the fuel it carries can be used in official operation, and the running time is longer.
Long Feng: So the main factor that limits its life now is fuel, not refrigerant. And like Spitzer, when it runs out of refrigerant, it can no longer work well in the mid-infrared band.
Silicon Valley 101: James Webb's launch still sounds very successful. You just mentioned that during his movement, he would encounter some micrometeorite impacts.
Will the impact of the black meteorite have a big impact on this telescope? Would its visor be shattered by a meteorite impact with serious consequences?
Lv Jianwei: This aspect was actually taken into account in the design. The visor was made of very tough materials, requiring it to be able to hold micrometeorites. The micrometeorite is actually only a few micrometers in size, similar to its observed wavelength, like some tiny dust crashing into it. Principles don't have to worry about this.
03 The challenge was so great that Ace Pigeon Weber was almost cut
Silicon Valley 101: Is it now out of orbit in the Starchain and into a safer area? How does it go?
Lv Jianwei: Less than 13% of the distance was left earlier today (arrived at the destination at 2 p.m. EST on January 24). At the speed at which it is now running, it should be 10 days before it reaches its intended location. This distance is already very far away from the Earth and the Moon, so there is no need to worry about the influence of Earth's artificial celestial bodies on it.
Figure | trajectory Image Source: Steve Sabia/NASA Goddard
Silicon Valley 101: Is its entire operation and the opening of the sunshade still going well?
Lv Jianwei: It went very smoothly. Scientists from previous projects summarized 344 "single points of failure." If one of the 344 steps fails, it fails. Now, through continuous effort, there are fewer than 50 single points of failure left. This is very exciting.
After it reaches the predetermined position, in order to ensure that it can operate according to normal indicators, it is necessary to carry out equipment commissioning and observation testing for about 5 months. If all goes well, it is expected that scientific observations will be officially carried out in June and July this year.
Silicon Valley 101: It will take about five months to return photos.
Lv Jianwei: Before that, he would send back the data to a small number of astronomers in order to calibrate the instrument, but it would not be made public. Before it officially starts observing, it may take some very nice photos to prove that the telescope is working properly.
"Silicon Valley 101": When hubble put the first photo from space, people found that the photo was mushy, his lens power was wrong, and he was short-sighted. It was three years before NASA sent astronauts to repair Hubble. This should be the first time someone has done lens repairs to a telescope in space.
Let's make a hypothesis, if we find a fault when Weber returns the photo, is it difficult to fix it?
Lv Jianwei: Yes. On the one hand, because it is so far from Earth, it is quite challenging to launch any manned spacecraft. On the other hand, James Weber's own design has almost no way to maintain it. It can be said that the designers themselves did not intend to do maintenance.
Hubble is smaller than James Webb, with a main diameter of only 2.4 meters. If a space shuttle is launched, it can be grabbed by the arms of the aircraft and allowed the astronauts to repair it directly. Because Hubble is small, it is easy to fix, but Weber is larger, so even if the spacecraft is launched, it is difficult to fix it for maintenance. There is a section in the movie "Gravity" in which the astronauts spin around after docking out of control.
Figure | Hubble vs. Weber sizes Source: NASA
The other is the James Webb Telescope, which has a mirror surface of 6.5 meters, which is very large. It is composed of splicing, and the mirror can no longer be closed after it is extended, it can only remain so large. So you have no way, and it's hard to make a good position fixation. However, in fact, a certain part of the James Weber telescope is still reserved for docking windows.
Long Feng: Looking forward to the day when our ability can be achieved.
Lv Jianwei: Maybe the current technology and repair capabilities have not yet been achieved, but there may be opportunities in the future. Maybe when the fuel is about to run out, you can launch a spaceship past and let the robot fuel it.
Long Feng: I'm curious about the next 50 things that may go wrong, which ones are the easiest or most deadly?
Lv Jianwei: I don't know if this list has been published. But I personally feel that there is a possibility of problems, including the cooling problem of the instrument itself, or the failure of electronic circuits. However, the list will contain events with very low probability, so in principle there should be no major problems.
"Silicon Valley 101": There is also a background is that James Webb announced that it is going to launch, it has been about 20 years, and everyone has been waiting for it. Is it expected for you to send James Webb to the sky this Christmas?
Figure | James Webb Funding and Time Change Source: Nature
Long Feng: Very unexpectedly, I was ready for it to continue to delay, at that moment, I only hope that he will not release the pigeons at the last moment.
Lv Jianwei: In fact, Webb compares with the historical space telescope project, and the extension is not very long. There is a lot of uncertainty about how much time it takes for all kinds of engineering matters, especially when it comes to high technology.
Including the James Webb Telescope, which has a key device when proposed, it is considered achievable. But then it was found that there were problems with electronic control and material strength. The number of times it repeatedly performs the action will not be particularly high, and the material will be strained. These are things that are hard to come up with when planning a project. Technical immaturity and poor planning of R&D time are an important reason.
At the same time, such projects become more complicated over time. The Weber project is large enough, involving more units, and a large number of people are prone to various problems.
On the other hand, due to human error in management. For example, when James Webb was testing at the South American launch site, once the accessories of a fixed telescope fell off, for unknown reasons.
This kind of thing is actually quite a lot in Weber's testing and maintenance process. For example, once when doing a vibration test on a telescope, it was suddenly found that the index of a detector was not normal. Before it does a vibration test, it needs to vacuum the environment to simulate the environment in space. At that time, a few screws were inexplicably gone, probably taken away by the exhaust fan during vacuuming.
Their five-story solar sails were torn apart as they unfolded, and the team had to make a new one.
Even a few months before the launch of the telescope, the propellers and carrier-based payloads of the launch vehicles were sent to Europe because of communication system problems. After that, they had to ask the manufacturer to make a new one for them to ship over. This incident also caused the telescope to be delayed for a while. It's common for large projects to make small mistakes.
In addition to the human factor, there is a third type of factor - pure natural factors. Because James Webb was manufactured long enough, he experienced many natural disasters. For example, earthquakes, floods, tsunamis, including some wildfires and the recent coronavirus, etc., have caused it to have some delays at various times that are not appropriate.
This is quite common for this kind of space project, often taking 10, 20 years or even 30 years to see its true success, and many space projects have a survival rate of only one in ten.
For example, in the 90s, the United States was going to build a large particle collider. Halfway through, suddenly Congress felt that it was too expensive and that there was a mistake in management, so it cut it.
Also because of the delay too long, the budget too fast, management problems and other reasons, James Webb was almost cut by Congress in 2011, through unremitting efforts to finally successfully launch.
Silicon Valley 101: I think it's really not easy. James Weber is also a transnational cooperation project, multinational cooperation and political game, but also requires everyone to be very rigorous, which sounds quite great.
Lv Jianwei: According to NASA statistics, before and after the James Webb project, the number of participants should exceed 10,000 people, and the number of participating countries should exceed 14 countries.
04 Everyone has the opportunity to apply for observation
Silicon Valley 101: If Weber starts working afterwards, what will happen to the future observation time? Can everyone apply to use this telescope?
Lv Jianwei: Yes, everyone can apply, even if they don't do astronomy, if your application can be good enough. The observation application notice made a year ago has received observation applications from about 30 countries in the world. This is open to scientists all over the world.
Another good thing is that astronomy projects, whether spatial or ground," tend to be fully public after a period of time, and no one hides the data themselves. These can be downloaded online, and even many astronomy enthusiasts, post-download photos are more beautiful than astronomers.
Image | Hubble telescope photographed the star sail Image source: ESA/Hubble & NASA
Long Feng: Is the time point of secrecy of the Webb telescope one year? Is it the same time as our ground-based telescopes?
Lv Jianwei: Yes, most of the projects are retained for one year, but a very few projects require that the data be immediately disclosed.
Long Feng: This year is as the PI of the project (Principal Investigator project leader) can propose a telescope, and the period after data collection for one year is unique to the project team and can be used to publish scientific research results. The data will be made public after a year and will be available to all.
Different projects, in fact, most of the time will still be given to scientists in participating countries. For Weber, they have a percentage of what percentage can be used as an opening time to apply to people in all countries. For example, if I return to China after that, how much lower will the rate of application success be than in the United States?
Lu Jianwei: Their current review is completely anonymous, but according to the results of the first round of observation application review, some countries that are not involved in the James Webb project at all have time.
Silicon Valley 101: How much observation time did your school get?
Lv Jianwei: In addition to the infrared astronomy group in our school, there are other astronomers and research groups. The entire James Weber ran 13% of the observation time in his first year and was allocated to our school's astronomers. At present, the unit with the most time in the world is our school.
Silicon Valley 101: Is the 13% of the observation time that your school gets priority, or is it obtained in the same order as when you apply publicly?
Lv Jianwei: These are two types. Our school's Infrared Astronomy Group, allotted a few hundred hours of time, simply write a simple science plan. Their audits are very lenient and have few restrictions.
There is also a large part of the more general ordinary applications. This requires writing an observation plan in advance, detailing the purpose, value, technical means, design details, etc. This is a lot of people competing on the same stage, and there is a strong choice.
Silicon Valley 101: Do you two have a plan to submit now?
Long Feng: I personally did not, but the last time I applied for participation in the three projects, I got the time. I also plan to give it a try starting this year.
Lv Jianwei: I did not win the PI myself, but I participated in several of them, including one that I wrote half of.
Long Feng: In terms of observation, some ordinary observation telescope equipment, we are divided into ordinary experience and large project experience, and the time of large projects needs to exceed a certain standard. For example, if a device I work on a lot of time is more than 100 hours, it becomes a big project. I wonder if Webb has such a distinction? What kind of projects become big projects?
Lv Jianwei: It does have a distinction. Observations of more than 60 hours should be considered a big project. The process of reviewing large projects will be more difficult than for small projects. You have to spend a long time on a project, and more people will participate in the review process, ensuring the possibility of scientific realization. Its design is reasonable, and the results are important.
Long Feng: But a big project can be a very big boost to a certain field, which is why it needs to spend so much time to complete this scientific goal.
05 In the eyes of astronomers, aliens are 100% present
Silicon Valley 101: I'd love to ask a common question in the minds of many people, do you believe there are aliens in the universe? I know that in astronomy circles there are a lot of different statements about this issue, and I would like to know what your personal opinion is on this issue?
Long Feng: I believe in their existence. The universe is vast, and we've found more than 5,000 exoplanets. We are actively searching for what their atmosphere looks like and whether they can sustain their existence. These thousands of planets have been discovered in a very short period of time in the past decade. If our equipment and means of observation continue to improve, we will find more. If your sample is large enough, there are always one or two that may be able to support life, and that may be able to give birth to the existence of the same or different life forms.
Lv Jianwei: I think aliens must exist, I can say 100% of that. Our current understanding of science, including the knowledge that matter is made up of some basic elements, gravity, etc., is the same thing. For example, the orbit of the Earth can be expected according to the practice of Newtonian mechanics and the correction of gravitational relativity.
There is an astronomical idea called the Copernican principle. He proposed that everywhere in the universe is basically the same. Neither the Earth, the solar system nor the Milky Way itself has anything peculiar in the universe, they are just a random point in the universe. The basic composition of the universe, including the laws of physics, is basically not much different in the sky.
So the origin of life is actually the result of a very natural material evolution, and there is nothing divine in it. This is a product of nature.
When the environment of your celestial body, temperature, elemental composition, the distance between the main stars and other certain conditions, the birth of life is a natural process. Just as we know that planets are born around stars, stars are born in galaxies, it's just that the complexity and physical scale are different. But as long as the laws of physics are the same, there is no reason to say that only the earth has life in the whole universe.
Silicon Valley 101: The two men's view is basically that there are aliens. So earth can't get signals about aliens?
Lv Jianwei: What kind of means do you want to detect this alien signal? It may be said to build telescopes or make radio wave receivers, because it is thought that aliens may send some signals to Earthlings, which is the way everyone thinks of communication.
But we have only been inventing astronomical telescopes for more than 400 years, and the real application of radio waves is 100 years, which is very short compared to the 13.8 billion years of age of the universe. Shrinking the time of the universe from the birth of the Big Bang to our present day to the time mark of a year, the invention of the telescope by mankind includes the centuries of the Industrial Revolution, just like the second of December 31 at 23:59:59 pm in the universes of the year.
Figure | From the Big Bang how far telescopes can see Source: NASA and Ann Feild
Compared with such a long time in the universe, the technology produced by human civilization is only a small point in time. If you can see aliens in such a short period of time, it proves that the density of alien civilizations is very high.
"Silicon Valley 101": Can we understand, in fact, we put James Webb into space this time, and the problem it wants to study is also to solve the very basic questions of whether there is an alien civilization in the universe and what is the origin of the universe.
Lv Jianwei: The guidance of NASA's science popularization department is that once everyone says that James Webb is looking for an alien civilization, it is necessary to correct it in time. There is a high probability that James Weibo will not directly detect the signals of extraterrestrial civilizations, and the public cannot be expected to be wrong.
The thing that has more to do with the origin of life is that it can photograph the surface atmospheres of some planets outside the solar system, around other stars and in planetary systems. Previous telescopes on the ground were not sensitive enough to cover wavelengths. But with the James Webb telescope, it is possible to capture spectra of some exoplanet atmospheres.
Through this spectrum you can judge its atmospheric composition. Does it contain a lot of water, carbon dioxide or the like? It may help pick out some or a group of planets with potential for life. But to judge whether there is civilization above? I think James Webb probably couldn't do it.
Silicon Valley 101: So he can only find these planets.
Long Feng: Find the most likely and representative ones, and then we will see if there is any way to study them in more detail.