This article is from WeChat official account: acoustic situation of (ID: fyvoice) , author: Yuan Lanfeng , Editor: Sun Yuan, the original title “Some people think that FAST is a money-burning fraud-can’t grow crops after hearing the crickets cry?” | Yuan Lanfeng”, head picture from: Wikipedia
Recently, many people transferred me a chat record, claiming to be “Discussion that the old alumni of the astrophysics group of HKUST alumni group invested 670 million yuan in China, which caused a waste of time”, and said, “This waste and a swarm of chips. Tactics are not advisable…”. The “Sky Eye” mentioned here is the 500-meter spherical radio telescope (Five-hundred-meter Aperture Spherical radio Telescope, referred to as FAST) located in Dawodang, Guizhou.< /span>, the world’s largest single-aperture radio telescope.
FAST before construction (top left) and under construction (bottom) and design sketch (top right). Image source: Li & Pan (2016)
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The reason for denying FAST in this chat log is mainly that a new aperture synthesis technology has been developed over the past 50 years.(aperture synthesis technique), the combination of several small telescopes is equivalent to a large telescope. Therefore, large-aperture telescopes such as FAST are no longer being developed internationally. “However, Tianyan caters to the preferences of some Chinese and leaders and strives for the first place in the world, no matter what kind of first it is.”
They denounced FAST as “at the beginning of the design, its design concept is out of date”. “Burning the people’s blood and sweat! Where are the real useful results of scientific research? The chip leap forward is here again! It is nothing more than continuing to burn money for fraud.” “Why is this academy of sciences so backward and stupid? It is a real joke of the world to become the world’s first!” p>
Many people asked me what I think about this, my basic answer is one sentence:
You won’t grow crops by listening to the crickets?
The specific explanation is:
If you search for articles on anti-relativity and anti-quantum mechanics, you can find a lot of them immediately. It is often said that quantum communication is fake and that Pan Jianwei is a liar.
If you want to understand this kind of professional problem, you need to turn yourself into an expert first. If you don’t want to spend time and energy to learn, or if you don’t understand, then you have no attitude or just listen to experts. The problem for many people is that they don’t understand and they like to mix things up.
Astronomical professionals know that single-aperture large telescopes and telescope arrays are two different development directions, each with its own advantages. The former has high sensitivity (that is, it can detect very weak signals), the latter has high resolution (that is, two signals that are very close together can be distinguished). Each has a suitable field, it is not useless to have one another. In fact, researchers will try to combine the observation data of the two methods.
How can FAST pass the project if you can’t figure out such basic issues?
FAST designer and builder, National Astronomical Observatory Researcher, Chinese Academy of Sciences Nan Rendong (1945-2017)
In addition, my friend Liu Xinying, a professor at the Institute of Energy for Sustainable Development in Africa, University of South Africa, pointed out:
There is a famous international telescope array called SKA(Square Kilometre Array, Square Kilometre Array), which is under construction China, China is also one of the major players. In the early days of the SKA project, China proposed the KARST plan to build about thirty radio telescopes with a diameter of more than two hundred meters in the southwest. FAST was originally part of this KARST array.
The first phase of SKA running at night. The picture shows the SKA reflector antenna and low-frequency aperture array. The background is MeerKAT and ASKAP reflector antennas (https://www.sciping.com/31304.html)
My colleague and Professor Cai Yifu of the Department of Astronomy at HKUST pointed out:
FAST has just received two Nature articles, which will be published soon, and several new rapid radio bursts have been discovered. How can anyone think it is a fraud? In addition, FAST has made a big improvement, because radio data is generally a massive amount of data, so they developed a set of algorithms for quickly screening physical information. Internationally, it seems that many research groups are already using this method one after another.
These two are more professional reviews, and many friends have provided short reviews.
For example, my friend A said: “Professionals are too disrespectful. This is not the era of illiterate leaders in power.”
My friend B said: Don’t the people who created those discussions in the WeChat circle know? It seems that the people who built FAST didn’t know that the small telescopes were connected to each other.
My friend C said: FAST can be useful. It is more than just the construction money to generate income for the tourism industry in Guizhou.
My friend D said: Compared with Beijing’s housing prices, FAST is too cheap, and can’t afford a 670 million building. Let the scientists explore, what can they do even if they find nothing?
Very good, everyone seems to understand the truth. Then, my friend E asked a constructive question: What is the next discovery of FAST? Are there any internal spoilers?
My answer is: You can refer to the article by two of my astronomer friends, which was transferred by “The Voice of Wind and Cloud”, Dr. Zheng Zheng’s “Mr. Tian’s Eye to See the Universe: From Pulsar to Alien”|He Sai Dr. Liu Boyang’s ““Chinese Sky Eye” starts a search for extraterrestrial civilizations. Can you really find it? | Astronomy Gossip Learn“.
A little more specific. FAST is designed to operate at a frequency of 70 to 3000 MHz, which is similar to the frequency of radio and mobile phone signals. In this frequency band, FAST is the most sensitive in the world, and you will cause serious interference if you call a cell phone nearby. Therefore, within 5 kilometers of FAST, it is set as a radio silent zone. Those who visit it must first store electronic equipment such as mobile phones, computers, digital cameras, etc., and are not allowed to bring them in. Even the start and ignition of tourist vehicles in scenic spots were shielded.
I visited FAST at the invitation of the Central Cyberspace Administration of China and Guizhou Province in 2016, and found that Guizhou Province gave it a very literary name called “Quiet Tourism”. At that time, I was impressed by storing the equipment before entering the scenic spot, and camping under the stars in a tent that night. Everyone feels lost without a mobile phone, worried about how to contact home. The organizer said: You can use the phone next to it. Only then did I realize that many people have forgotten that there is something called a “fixed phone”!
At that time, many media reporters were with us and wrote many reports. However, reporters have limited knowledge of science and cannot write about what FAST can do. They just posted a lot of literary and artistic emotions, for example: In such a “quiet” environment, “abandon the worldly turmoil, and let people face their own soul and think about life”.
FAST night view (http://news.sina.com.cn/o/2016-11-07/doc-ifxxmyuk6173099.shtml)
Well, after thinking about life, you must still want to ask: What can FAST do?
The basic answer is: The FAST Scientific Committee has selected and initiated five priority and major projects, and 50% of the observation time is spent on these projects. The five major projects are:
(1) Simultaneous sky survey by drift scanning of multiple scientific targets;
(2) Galactic pulsar survey;
(3) Pulsar time measurement;
(4) M31 neutral hydrogen imaging and pulsar search;
(5) Fast radio bursts.
To simplify again, the first four are pulsars and neutral hydrogen, and the last one is a fast radio burst.
Let’s talk about Pulsar(Pulsar) first. It is a celestial body that emits pulsed electromagnetic signals at a very precise cycle, so accurate that it can be used as a clock. It is generally believed that a pulsar is a neutron star, that is, a planet composed entirely of neutrons. The periodic signal is caused by the rapid rotation of the neutron star.
On August 22, 2017, FAST discovered a pulsar while it was still being debugged. At present, FAST has detected more than 100 new pulsars, and thousands of pulsars are expected to be discovered during the entire survey.
FAST discovered the first pulsar art image (above) and the first millisecond pulsar (below, the pulse period is about 5.19 Milliseconds), picture source: Wang Pei
(Seeing the universe with the eyes of the sky: from pulsars to aliens | Mr. Sai)
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The second is Neutral Hydrogen, which is the hydrogen atom, which is the simplest atom with one proton and one electron. The simplest atom is important because it is the most common atom in the universe. The main materials of gas and stars in galaxies are hydrogen atoms.
M31 is the closest large spiral galaxy to the Milky Way. The picture above is an optical band photo of M31; the picture below is a 21 cm line image of M31 neutral hydrogen taken with a 26-meter radio telescope (bottom left), and the speed of different parts of M31 measured with a 21 cm line (bottom right). Optical pictures are from Toren Hansen (wikipedia), and neutral hydrogen pictures are from Chemin, Carignan & Foster (2009)
(Seeing the universe with the eyes of the sky: from pulsars to aliens | Mr. Sai)
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The largest radio telescope before FAST was the Arecibo Telescope(Arecibo Radio Telescope) in Puerto Rico. The aperture of FAST is 500 meters, and the aperture of Arecibo telescope is 305 meters.
Arecibo Telescope (Picture copyright: Arecibo Observatory H. Schweikerm)
The Arecibo telescope once did a neutral hydrogen survey, sweeping about 1/6 of the sky and detecting more than 30,000 galaxies outside the galactic. This is the deepest large-area neutral hydrogen survey outside the river. Now FAST’s drift scan survey intends to fully surpass it, covering more than 1/2 of the entire sky, and it is expected to see hundreds of thousands of extragalactic galaxies.
The hydrogen atom gas distribution image of the Milky Way obtained by the Arecibo telescope (three partial mosaics, from the GALFA-HI sky survey)
Not only that, FAST also intends to search for signals from neutral hydrogen and pulsars at the same time. Previously, these two surveys were conducted separately. This is the first project mentioned earlier, FAST multi-scientific target simultaneous sky survey (Commensal Radio Astronomy FAST Survey), CRAFTS for short. This new technology will greatly accelerate the speed of sky surveys.
CRAFTS Project (crafts.bao.ac.cn; Li et al. 2018)
The last one is a fast radio burst (Fast Radio Bursts in English, FRB for short). It is a very powerful radio burst that can release the energy released by the sun throughout the day within a few milliseconds to tens of milliseconds. This phenomenon was first discovered in 2007, and we do not yet know its physical origin. In November 2018, FAST discovered the first new fast radio burst FRB181123(Seeing the universe with the sky: from pulsar to alien | Mr. Sai). More observations in the future may reveal the answer for us.
What made fast radio storms famous among the public was the “Canadian Hydrogen Intensity Mapping Experiment” radio telescope (CHIME) in early January 2019. span> reported 13 FRB incidents detected within two months, of which one FRB signal was repeated 6 times(< a href="https://mp.weixin.qq.com/s?__biz=MzI0NzQzMjU3Ng==&mid=2247491379&idx=1&sn=cc2151c4f08240d296c6c00d026f3193&scene=21&token=372777765&lang=zh_CN rel="nofredirect" style="nofrenk" target ="text-decoration: none;">Are there aliens coming? It’s like hearing something in the middle of the night, saying “do not rule out haunting” | China Daily a>).
13 animated schematic diagrams of rapid radio bursts (motion pictures)
Many media said that this is a signal from aliens.
The title of the British “Guardian”: The mysterious fast radio burst from the depths of the universe “May be an alien”
So this news suddenly hit the circle of friends, and many people exclaimed: “Don’t answer! Don’t answer! Don’t answer!!!”
Don’t answer!
When I was interviewed by “China Daily” (China Daily) at that time, (Aliens are here? It’s like hearing movement in the middle of the night, if you say “do not rule out haunting” | China Daily), he pointed out : Friends who read “Don’t answer” can understand, but even if you want to answer, now There is no technical means at all.
As far as FAST is concerned, it is a receiving device, not a transmitting device. Even if you want to send a signal to the outside world like Ye Wenjie, you can’t send it out.
Ye Wenjie and Hong’an Base
This leads us to the last question we want to discuss: I heard that FAST opened the exploration of alien civilizations. Is this true?
The answer is: true. FAST is in charge of the National Astronomical Observatory of the Chinese Academy of Sciences. On April 28, 2020, their website reported “FAST opens the search for extraterrestrial civilization“.
FAST opens the search for extraterrestrial civilizations
Specifically, search for extraterrestrial civilizations(Search for ExtraTerrestrial Intelligence, referred to as SETI) Is one of the five scientific goals of FAST. The discovery of more and more extraterrestrial planets, coupled with the revolutionary advancement of instruments and observation capabilities, has led to the revival of SETI research. Since FAST has the highest sensitivity in certain frequency bands, it will inevitably become the main force of SETI.
Sensitivity comparison of telescopes currently participating in SETI research under the same observation parameters (from the “Astronomy 2020” proposal written by Margot et al.)< br label="picture note" class="text-img-note">
The FAST team released a quantitative outlook for the SETI sky survey on April 27, 2020. Based on the test observation of super-earth GJ 273 b and the calculation of isotropic equivalent power of extraterrestrial civilization (EIRP), FAST has the potential to detect To the Earth-Like Exoplanet Survey Satellite (TESS) will announce the terrestrial civilizations on thousands of extraterrestrial planets, and the nearby galaxies Andromeda Galaxy (M31-Andromeda)The second category of Kardashev(Kardashev type II) or more advanced civilization.
Quantitative Outlook for SETI Sky Survey
The second type of Kardashov civilization mentioned here can be found in my 2015 article “How fast is China’s scientific and technological strength approaching the United States“, where the transliteration of “Kada Xie” is husband”. The second type of Kardashov civilization means: a civilization that can use the energy of the entire star to transmit information.
Kadasev Scale
If you don’t understand these many terms, it’s okay. The basic point is one sentence: FAST has the hope of discovering alien civilizations!
However, since the universe is so vast, there are countless types of signals that may be emitted by a smart civilization, and we just wait and see if there are electromagnetic waves emitted by others.(Can’t receive the information of alien civilization, is it because the mathematics system is different? | Global Science). So all we can say is that FAST is the main force in the existing SETI detection instruments.
This in no way means that FAST has great hopes of finding aliens, nor does it mean that aliens have been found. Therefore, our best attitude is to be calm, aiming at scientific progress, not aiming at finding something.
After all, curiosity is the most fundamental driving force of science. “Heavenly Questions” such as FAST and the Mars probe launched not long ago, and Chang’e-5 that will be launched later, will lead us to surpass ourselves.
Background introduction: Yuan Lanfeng, Ph.D. in Chemistry, University of Science and Technology of China, Associate Researcher, Hefei National Research Center for Microscale Material Science, University of Science and Technology of China, Society of Science and Technology and Strategy Chairman, speaker of the “Science and Technology Yuanren” program, standing committee member of the Anhui Science and Technology Association, standing director of the China Youth New Media Association, selected as one of the top ten science communication figures in “Dian Zan·2018 Popular Science China”, Weibo @中科大胡不归 , Zhihu@袁岚峰(). The article was published on October 19, 2020 inThe Beijing News.
This article is from WeChat official account:Fyvoice (ID: fyvoice) author: Yuan Lanfeng