The 2020 Nobel Prize in Physics goes to Roger Penrose for his discovery that black hole formation is a prediction of general relativity; Reinhard Genzel and Andrea Ghez for the discovery of a supermassive compact object at the center of the Milky Way.
The author believes that Hawking will certainly win this year’s Nobel Prize during his lifetime. Judging from the tone of the Nobel Prize in recent years, it is very biased towards empirical research and not very friendly to pure theoretical research. For example, in the previous years of the Nobel Prize, whether laser physics, LED, or topological phase transition, all belong to empirical research, and LED and topology (that is, superconductivity) have been widely used. The last time the prize was given was in 2013, for the observation of the Higgs boson.
But the advent of big data processing, which allows us to correlate data from multiple instruments with much more accurate results, led to the first LIGO observations of gravitational waves and, in 2019, to the actual images of black holes. This not only confirmed the black hole, but also proved the existence of black hole radiation, also known as Hawking radiation. This is why Hawking would have won the Nobel Prize had he lived. But this year’s award is well deserved, for their undisputed theoretical predictions and unquestionable observational evidence for the existence of black holes
A black hole cannot be observed directly, but its existence and mass can be known indirectly, and its effects on other things can be observed. By objects before being sucked into the friction caused by black holes of acceleration of gravity and emit x-rays and gamma rays edge “message”, to determine whether the real black holes, and before the advent of black hole photos, the study of black holes could not have won the Nobel Prize, and the actual observation study of black holes and how under the blessing of big data technology, measuring gravitational waves, To photograph black holes, it all started with the Michelson-Morley interferometer.
LIGO predecessor – Michelson-Morley interferometer
At the beginning of the last century, more than a hundred years ago, light was thought to travel through the ether. This creates a new problem: To move around the sun at 30 kilometers per second, the Earth must encounter the 30 kilometers per second “aether wind” blowing in its face, and it must also affect the propagation of light. The emergence of this question has led people to explore the existence of “ether wind”. The Michelson-Morley experiment was carried out on this basis.
As shown in the figure, the experimental instrument can be simplified to a light source, two reflectors, a spectroscope and an observation screen. The function of the spectroscope is to divide the light emitted by the light source into two parts with equal intensity. One part can pass through the spectroscope and reach the reflector M1 along the original direction, while the other part will be reflected and reach M2 along the direction perpendicular to the original direction. After THE reflection of M1, M2 will return to the spectroscope, and the spectroscope will split again. At this time, part of the reflected light from M1 will be reflected to the observation screen by the spectroscope, while part of the reflected light from M2 will be transmitted to the observation screen by the spectroscope. Because the distance from the spectroscope to M1 and M2 (set as D) is equal, and the two rays reaching the observation screen are both reflected by the primary spectroscope, transmitted by the primary spectroscope and reflected by the primary reflector. So if the instrument is absolutely stationary, the paths of the two beams should be exactly the same when they reach the screen.
But if, according to the theory of the day, the earth had a velocity relative to the aether, then the instrument was not absolutely stationary. We assume that the speed of light relative to the etheric for c, earth movement speed v, ether and the same as the light source to the direction of the M1, so according to the principle of superposition of Galileo speed, the beam splitter can get passed tem and reach the mirror M1 before that time, the hypothesis device in the etheric to speed v movement to the right, And the distance from the partially silver-coated glass sheet to the two mirrors is L, then the light beam to the right has a relative speed of C − V in the process of moving to the right, the time it takes t1= L/ (C − V), and the speed of return is C + v, the time t2= L/ (C + V).
And for the light that’s going up, let’s say it takes time to reach the mirror, t3, and in that time the mirror moves to the right by VT3, so the distance traveled by the light is the hypotenuse of a right triangle, so we have theta
The available
And the return time is the same as this, so the total time
Because the two beams of light are generated by the same light source and the optical path difference is constant, the interference of light should occur on the observation screen, resulting in interference fringes. If you rotate the instrument, the speed of the two beams relative to the Earth will change, so will the path difference, and the resulting interference fringes will shift. And we can use the movement of the stripes to determine how fast the earth is moving relative to the ether. But the results were disappointing and shocking: no matter how much the instrument was rotated, the two beams showed no difference in time. Michelson and Morley conducted several more experiments, but the results were still negative, and subsequent experiments were reluctantly cancelled and declared “failed”. At this time, some conjecture was put forward to try to perfect the Aether theory and explain this experimental phenomenon.
Some people say that the earth is stationary relative to the aether, so this experiment does not yield any results. But it seems to have the same color as the geocentric theory, which places the Earth at the center of the universe. This went against the prevailing wisdom of the time, and the earth rotated, so there was no support for the hypothesis. It has also been proposed that the motion of the earth drags this etheric motion, causing the Earth to be static relative to the surrounding etheric. But the question of exactly how earth dragged the ether and why it did not lose energy as it did so was unanswerable and thus unrecognized.
But this was explained later by Einstein’s special theory of relativity in “On the Electrodynamics of Moving Bodies,” which stated that all inertial reference frames are equivalent and that light in a vacuum has a constant velocity relative to any inertial reference frame, and a series of inferences based on this. Einstein’s theory of space and time, which had not changed since the beginning of recorded history, was unacceptable, but eventually numerous experiments proved that his special theory of relativity was correct. Then Einstein came up with his even more astonishing theory of general relativity. Under the general theory of relativity, massive objects distort the space-time around them. When objects move — say, two celestial bodies rotating around each other — they cause ripples in the space-time around them, just as a distorted surface of water causes waves to spread outward. These ripples are called gravitational waves.
LIGO was instrumental in the capture of gravitational waves
Although many aspects of general relativity have been tested experimentally, the prediction of gravitational waves was not confirmed until LIGO appeared. And the instrument for detecting black hole gravitational waves, the largest of its kind today, the Laser Interferometer Gravitational-Wave Observatory, or LIGO, is actually a huge, mainly Michelson interferometer, and LIGO is run by Caltech and MIT, and it’s one of the largest scientific projects funded by the National Science Foundation.
The LIGO Hanford Observatory, or LHO, is located in Hanford, Washington. It has three detectors at two sites, the 4km and 2km two-armed LIGO Hanford Observatory, The LIGO Livingston Observatory (LLO), a four-kilometer-long two-armed probe, is located in Livingston, Louisiana, 3,002 km from Hanford. LIGO uses a variety of cutting-edge technologies. The vacuum system is one of the largest and purest systems in the world. The optical devices have unprecedented accuracy and can measure the displacement 1,000 times smaller than the size of a proton. Combined with big data, the computing facilities of LIGO are capable of processing huge experimental data. Since 2002, LIGO has officially started to collect data. By 2010, it has completed six scientific probes, and the optimal sensitivity has reached 10 orders of magnitude.
From 2009 to 2010, LIGO was upgraded to Enhanced LIGO and its sixth scientific probe, S6, was conducted. Its laser power is increased from 10 watts to more than 30 watts, and its detection range can be expanded eightfold. Between 2010 and 2015, LIGO had an upgrade program called Advanced LIGO, or aLIGO. In 2015, aLIGO went into service, increasing the laser power from the original LIGO’s 10 watts to around 200 watts. The lower detection band was extended from 40Hz to 10 hz, and the sensitivity was 10 times higher than the original LIGO. This means aLIGO can detect gravitational waves 10 times farther than the original LIGO. The detection range has also expanded by more than 1,000 times, making it possible to detect 1,000 times more possible sources of gravitational waves than before.
It was only a matter of time before the black hole veil was finally lifted
As we said before, the Nobel Prize is not friendly to unproven theoretical research, but once someone actually takes a picture of a black hole, it’s only a matter of time before a prize is awarded for black hole research.
The gravitational pull of a black hole is so strong that even light cannot escape beyond its event horizon, but Hawking’s theory of black hole radiation also predicts brilliant accretion disks around black holes. Normally, when we photograph an object, we take a picture of it by capturing the light that radiates from it or reflects it from something else, but because of the nature of black holes, this image does not have the face of the black hole.
According to Einstein’s theory of general relativity, anything with mass has a bending effect on space, and the bigger the mass, the more pronounced the bending effect.
So if an object density particularly big, so he can press the space around into a ball and leave no dead Angle of 360 degrees to intercept any particle want to escape, so at this time the body would collapse into a black hole, and the edge of the black hole is called the event horizon of a black hole, the event horizon to stop its internal escape behavior of any object.
If the black hole is compared to a mysterious bride, then she must be very cold, for example, a black hole with the mass of the sun is only 60nK, the temperature is extremely low, but due to its huge attraction, so that all objects passing it are deeply attracted, can not easily turn away. An accretion disk consists of the diffuse matter around the black hole, rotating around the central body of the black hole. The attraction plate is like the crowd tightly around the bride, they gather around her for a look at the bride, constantly turning, constantly close, here are so crowded, extraordinary heat. Because of the constant friction between matter, the accretion disk is much hotter than the black hole, and he is like a dazzling light at a wedding, lighting up the whole place.
Black hole temperature is low but it is not, of course, no heat, according to quantum theory always create plenty of positive and negative particles in the space, then the positive and negative particles together and annihilate is empty, and if the pairs of positive and negative particles just child was produced on the event horizon of a black hole, one of the particles may drop into a black hole would never come out, and the other particles, Because its escape velocity at the edge of the event horizon is equal to the speed of light, it is lucky enough to escape and produce this black hole radiation.
As a distant observer, the radiation from the black hole itself is almost impossible to capture. The only way to get a glimpse of the black hole is through the intense thermal radiation produced by the accretion zone. But a picture of a black hole is still very difficult, because the observable black holes are too far away from the earth, and mankind into the black hole photos last year from M87, she is located in the virgo cluster in the direction of a giant elliptical galaxy, distance is about 55 million light-years away, M87 [lower right] a supermassive black hole in the center (now the silver heart naming habits of black holes is called M87 *), Its mass is about 6.5 billion times the mass of the sun.
The nice thing about M87* is that its accretion disk is very active, it’s very massive, but this black hole is really, really far away. Therefore, very Long Baseline interferometry (VLBI) technology is used to take photos. From the design idea of VLBI, the shadow of big data technology can be clearly seen. If we observe the same object in different positions at the same time, then each observation value and each observation site will show a specific geometric relationship. Then the relationship between the observed values can be used to estimate the true values more accurately.
The mutual achievements of physics and IT technology
The Event Horizon Telescope (EHT) is actually a virtual Telescope consisting of eight radio telescopes. They are: The South Pole telescope (SPT), Chile’s atacama large millimeter wave array (ALMA), Chile’s atacama pathfinder experiment (APEX) telescope, large millimeter wave telescope (information) in Mexico, Arizona, submillimeter telescope (SMT), Hawaii submillimeter telescope (SMA), the United States Hawaii of maxwell’s hope The Telephoto (JCMT), and the Spanish Radio Observatory’s 30-meter Millimeter Wave Telescope (IRAM). The eight telescopes, timed and synchronized by the same atomic clock, used big data processing to form a giant virtual telescope that accomplished the impossible task of photographing the black hole. Which is why its next target, Sagittarius A, the center of the Milky Way, will require even more data processing power.
Whether IT is the big data technology of LIGO or the astronomical telescope array used for black hole photography, the combination of physics and IT has become a trend, such as the FAST China Sky Eye radio telescope in Guizhou, China.
FAST is a five-hundred-meter Aperture Spherical Telescope (FAST), It consists of an active reflecting surface system, a feed support system, a measurement and control system, a receiver and a terminal, and an observation base. From the public data, the daily observation data generated by a radio telescope of this level, even after compression, is as high as 50TB. Then follow that participate in the black hole of astronomical telescope data observed quantity also basically in TB level, can say the same astronomical information brought by the astronomical observation, scale, from the generation of black hole photos, also means that huge manpower, calculate the force and operating costs, how to low cost, high efficiency to deal with huge amounts of information were collected, Is undoubtedly the most difficult problem facing astronomers.
In the early years, NASA scientists made an effort to educate the public about astronomy, releasing lots of carefully manipulated images of black holes and the sky in order to make stargazing more interesting and get funding from Congress. In fact, astrophysics is a data-driven science, and the combination of IT technology with artificial intelligence can often achieve unexpected results. More than 20 years before deep learning became popular, the National Astronomical Observatories began to use deep learning to predict sunspot activity. To sum up the system requirements in astronomical science, there are mainly two points:
Information cluster analysis:
The nature of its work is to sort through and figure out the connections behind it, but electromagnetic signals are everywhere in the universe, and it’s likely that pulsars are behind the periodic pattern. Pulsars are like lighthouses for ocean navigation, helping us determine the “coordinates”, the anchor points for analysis.
Result data transmission:
At the same time, it is difficult to convey the vast amount of information that deep learning depends on. Before the adoption of cloud computing technology in research institutions, if there was a need to transfer data, astronomical researchers had to carry hard disks on their backs. However, after the completion of the cloud project on the China Virtual Observatory, all kinds of problems can be easily solved, no matter data processing, transmission, storage and sharing.
However, in order to process such a large scale of data, there was an urgent need for computing power, so at that time, we had to use a large physical supercomputing, which was not only costly, but also not ideal. Thanks to the rapid development of IT technology, especially in cloud computing technology, gives strong support to the astrophysical study, based on the general operating system, ali’s flying vlsi connect millions of servers into a “super”, build the “global astronomical resources platform”, not only the global astrophysicist provides data support, including FAST eye, It also uses the computing power it provides for processing, and the efficiency can be increased by more than 20 times. What used to take seven days now takes eight hours. The production cycle has also been shortened nine-fold, from 180 days to 20 days.
In the process of exploring the stars and oceans, human beings often receive unexpected gifts. For example, Australian physicist John Osaliven invented what many young people use today — Wi-Fi. British physicist and Nobel Laureate Marty Lall invented synthetic aperture imaging, a technique that has been used in medicine as CT, MRI and PET emission-side scans. And because of the large amount of data and many similar pictures, astrophysicists have also contributed a lot of high-precision image recognition algorithms for us; It can be said that the physical research institute will feed the technological achievements to the whole society, into our daily life. Also wish our country to explore the stars and the sea to a higher level, breakthrough progress.