"Interstellar": fantastic truth? Theoretical physics of Kip Thorne in the film "Interstellar Gravitational Time Dilation"
I will try to answer a few questions that viewers have about the film.
1) Why does Gargantua's black hole look like this in the film?
The film Interstellar is the first feature film in the history of cinema to visualize a black hole based on a physical and mathematical model. The simulation was carried out by a team of 30 people (Paul Franklin's visual effects department) in collaboration with Kip Thorne, a world-renowned theoretical physicist known for his work in the theory of gravity, astrophysics and quantum measurement theory. About 100 hours were spent on one frame, and in total about 800 terabytes of data were spent on the model.
Thorne not only created a mathematical model, but also wrote specialized software (CGI), which made it possible to build a computer visualization model.
Here's what Thorne came up with:
Of course, it is fair to ask: is Thorne's simulation a first in the history of science? And is Thorne's image something never seen before in the scientific literature? Of course no.
Jean Pierre Luminet of the Paris-Mudon Observatory, Department of Relativistic Astrophysics and Cosmology, also internationally renowned for his work in the field of black holes and cosmology, is one of the first scientists to image a black hole using computer simulation. In 1987, his book “Black Holes: A Popular Introduction” was published where he writes:
“The first computer images of a black hole surrounded by an accretion disk were obtained by me (Luminet, J.-P. (1979): Astron. Astrophys.). More refined calculations were carried out by Marck (Marck, J.-A. (1993): Class. Quantum Grav) both for the Schwarzschild metric and for the case of a rotating black hole. Plausible images - that is, calculated taking into account the curvature of space, redshift and physical properties of the disk - can be obtained for an arbitrary point, even located inside the event horizon. A movie was even created showing how these distortions change as one moves along a timelike trajectory around a black hole (Delesalle, Lachieze-Rey and Luminet, 1993). The drawing is one of his frames for the case of movement along a suspended parabolic trajectory"
Explanation of why the image turns out this way:
“Due to the curvature of space-time in the vicinity of the black hole, the image of the system differs significantly from the ellipses that we would see if we replaced the black hole with an ordinary low-mass celestial body. The radiation from the upper side of the disk forms a direct image, and due to strong distortion we see "The entire disk (the black hole does not block the parts of the disk behind it from us). The lower part of the disk is also visible due to the significant bending of light rays."
Lumine's image is surprisingly reminiscent of Thorne's result, which he obtained more than 30 years after the Frenchman's work!
Why is it that in other numerous visualizations: both in articles and popular science films, a black hole can often be seen completely different? The answer is simple: computer “drawing” of a black hole based on a mathematical model is a very complex and time-consuming process that often does not fit into modest budgets, so the authors most often make do with the work of a designer rather than a physicist.
2) Why is Gargantua’s accretion disk not as spectacular as can be seen in numerous pictures and popular science films? Why couldn't the black hole be shown brighter and more impressive?
I'll combine this question with the following:
3) It is known that the accretion disk of a black hole is a source of very intense radiation. The astronauts would simply die if they approached the black hole.
And indeed it is. Black holes are the engines of the brightest, highest energy sources of radiation in the Universe. According to modern concepts, the heart of quasars, which sometimes shine brighter than hundreds of galaxies combined, is a black hole. With its gravity, it attracts huge masses of matter, forcing it to compress into a small area under unimaginably high pressure. This substance heats up, nuclear reactions take place in it, emitting powerful X-ray and gamma radiation.
Here's how the classic black hole accretion disk is often drawn:
If Gargantua were like that, then such an accretion disk would kill astronauts with its radiation. The accretion at Thorne's black hole is not so dense and massive; according to his model, the temperature of the disk is no higher than that of the surface of the Sun. This is largely due to the fact that Gargantua is a supermassive black hole, weighing at least 100 million solar masses, with a radius of one astronomical unit.
This is not just a supermassive, but an ultramassive black hole. Even the black hole in the center of the Milky Way has, according to various estimates, a mass of 4-4.5 million solar masses.
Although Gargantua is far from a record holder. For example, the hole in the galaxy NGC 1277 has the mass of 17 billion suns.
The idea of imagining such an experiment, in which people explore a black hole, has bothered Thorne since the 1980s. Already in his book “Black holes and folds of time. The Audacious Legacy of Einstein, published in 1990, Thorne examines a hypothetical model of interstellar travel in which researchers study black holes, wanting to get as close as possible to the event horizon to better understand its properties.
Researchers start with a small black hole. It does not suit them at all because the tidal forces it creates are too great and dangerous for life. They change the object of study to a more massive black hole. But she doesn’t satisfy them either. Finally, they head towards the giant Gargantua.
Gargantua is located near the quasar 3C273 - which allows you to compare the properties of the two holes.
Watching them, researchers wonder:
"The difference between Gargantua and 3C273 seems surprising: why doesn't Garnatua, at a thousand times its mass and size, have such a round donut of gas and giant quasar jets?"
Gargantua's accretion disk is relatively cool, not massive, and does not emit as much energy as a quasar does. Why?
"After telescopic research, Bret finds the answer: every few months, a star in the orbit of the central hole 3C273 comes close to the horizon and is torn apart by the tidal forces of the black hole. The remains of the star, with a mass of approximately 1 solar mass, are splashed in the vicinity of the black hole. Gradually, internal friction drives the spraying gas inside This fresh gas compensates for the gas that the donut is constantly supplying to the hole and the jets, so the donut and the jets maintain their gas reserves and continue to shine brightly.
Bret explains that the stars can come close to Gargantua. But because Gargantua is much larger than 3C273, its tidal forces above the event horizon are too weak to tear the star apart. Gargantua swallows stars whole without splashing their entrails into the surrounding donut. And without the donut, Gargantua cannot create jets and other features of the quasar."
For a massive radiating disk to exist around a black hole, there must be a building material from which it can form. In a quasar, these are dense gas clouds very close to the black hole of the star. Here is the classic model for the formation of an accretion disk:
In Interstellar, it is clear that there is simply nothing for a massive accretion disk to emerge from. There are no dense clouds or nearby stars in the system. If there was anything, it was all eaten long ago.
The only thing Gargantua is content with is low-density clouds of interstellar gas, creating a weak, “low-temperature” accretion disk that does not radiate as intensely as classical disks in quasars or binary systems. Therefore, the radiation from Gargantua's disk will not kill astronauts.
Thorne writes in The Science of Interstellar:
“A typical accretion disk has very intense X-ray, gamma-ray and radio emission. So strong that it will fry any astronaut who decides to be nearby. The Gargantua disk shown in the film is an extremely weak disk. “Weak” - not by human standards, of course, but by the standards of typical quasars. Instead of being heated to hundreds of millions of degrees, as quasar accretion disks are heated, Gargantua's disk is heated only a few thousand degrees, about the same as the surface of the Sun. It emits a lot of light, but emits almost no X-rays or gamma-rays. rays. Such disks can exist in the late stages of the evolution of black holes. Therefore, the Gargantua disk is quite different from the picture that you can often see on various popular astrophysics resources."
Is Kip Thorne the only one who suggested the existence of cold accretion disks around black holes? Of course no.
Cold accretion disks of black holes have been studied in the scientific literature for a long time:
According to some data, the supermassive black hole at the center of the Milky Way, Sagittarius A* (Sgr A*), has just the same cold accretion disk:
An inactive black hole may exist around our central black hole. cold accretion disk, remaining (due to low viscosity) from the “turbulent youth” of Sgr A*, when the accretion rate was high. Now this disk “sucks” hot gas, preventing it from falling into the black hole: the gas settles in the disk at relatively large distances from the black hole.
(c) Close stars and an inactive accretion disc in Sgr A∗: eclipses and flares
Sergei Nayakshin1 and Rashid Sunyaev. // 1. Max-Planck-Institut fur Astrophysik, Karl-Schwarzschild-Str. Garching, Germany 2. Space Research Institute, Moscow, Russi
Or Cygnus X-1:
A spectral and temporal analysis of a large number of observations by the RXTE observatory of the accreting black holes Cygnus X-1, GX339-4 and GS1354-644 in a low spectral state during 1996-1998 was performed. For all three sources, a correlation was found between the characteristic frequencies of chaotic variability and spectral parameters - the slope of the spectrum of Comptonized radiation and the relative amplitude of the reflected component. The relationship between the amplitude of the reflected component and the slope of the Comptonization spectrum shows that the reflecting medium ( cold accretion disk) is the main supplier of soft photons to the field of Comptonization.
(c) Report at SPIE organization Conference "Astronomical Telescopes and Instrumentation", 21-31 March 2000, Munich, Germany
Interaction Between Stars and an Inactive Accretion Disc in a Galactic Core // Vladimır Karas. Astronomical Institute, Academy of Sciences, Prague, Czech Republic and
(c) Charles University, Faculty of Mathematics and Physics, Prague, Czech Republic // Ladislav Subr. Charles University, Faculty of Mathematics and Physics, Prague, Czech Republic
Quiet black holes are similar to the hole in the Andromeda Nebula, one of the first supermassive black holes discovered. Its mass is about 140 million solar masses. But they found it not by strong radiation, but by the characteristic movement of stars around this area. The characteristic “quasar” radiation from the core of these galaxies. And astrophysicists came to the conclusion that matter simply does not fall into this black hole. This situation is typical for “quiet” galaxies, like the Andromeda Nebula and the Milky Way.
Galaxies with active black holes are called active, or Seyfert, galaxies. Seyfert galaxies account for approximately 1% of all observed spiral galaxies.
How a supermassive black hole was found in the Andromeda Nebula is well shown in the BBC popular science film “Supermassive Black Holes.”
4) Black holes are known to have deadly tidal forces. Wouldn't they tear apart both the astronauts and Miller's planet, which in the film is too close to the event horizon?
Even the laconic Wikipedia writes about one important property of a supermassive black hole:
“Tidal forces near the event horizon are significantly weaker due to the fact that the central singularity is located so far from the horizon that a hypothetical astronaut traveling to the center of a black hole would not feel the effects of extreme tidal forces until he is very deep into it. »
Any scientific and popular sources that describe the properties of supermassive black holes agree with this.
The location of the point at which tidal forces reach such a magnitude that they destroy an object that falls there depends on the size of the black hole. For supermassive black holes, such as those located at the center of the Galaxy, this point lies within their event horizon, so a hypothetical astronaut can cross their event horizon without noticing any deformation, but after crossing the event horizon, his fall towards the center of the black hole is inevitable . For small black holes, whose Schwarzschild radius is much closer to the singularity, tidal forces will kill the astronaut before he reaches the event horizon
(c) Schwarzschild black holes // General relativity: an introduction for physicists. - Cambridge University Press, 2006. - P. 265. - ISBN 0-521-82951-8.
Of course, Gargantua's mass was chosen so as not to tear the astronauts apart by the tides.
It is worth noting that Thorne's 1990 Gargantua is somewhat more massive than in Interstellar:
“Calculations have shown that the larger the hole, the less thrust the rocket needs to keep it on a circumference of 1.0001 event horizon. For a painful but tolerable thrust of 10 Earth gs, the mass of the hole must be 15 trillion solar masses. The closest of these holes is called Gargantua, located 100,000 light-years from our galaxy and 100 million light-years from the Virgo galaxy cluster around which the Milky Way orbits. In fact, it is located near the quasar 3C273, 2 billion light years from the Milky Way...
By going into Gargantua's orbit and taking the usual measurements, you are convinced that its mass is indeed equal to 15 trillion solar masses and that it rotates very slowly. From this data you calculate that the circumference of its horizon is 29 light years. Finally, he calculates that this is a hole, the vicinity of which you can explore, experiencing permissible tidal forces and acceleration!"
In the 2014 book “The Science of Interstellar,” where Kip Thorne describes the scientific aspects of working on the film, he already gives a figure of 100 million solar masses - but noting that this is the minimum mass that a “comfortable” one can have in relation to tidal influences. black hole forces.
5) How can Miller's planet exist so close to a black hole? Will it be torn apart by tidal forces?
Astronomer Phil Plaint, known as "Bad Astronomer" for his unbridled skepticism, simply couldn't get past Interstellar. Moreover, before that, he viciously destroyed many acclaimed films, for example “Gravity,” with his drilling skepticism.
“I was really looking forward to Interstellar... But what I saw was terrible. This is a complete failure. I really, really didn’t like it.”- he writes in his article dated November 6th.
Phil says that the scientific part of the film is complete bullshit. Which, even in a hypothetical framework, cannot correspond to modern scientific ideas. He especially traveled around Miller's planet. According to him, a planet can stably orbit such a black hole, but its orbit must be at least three times the size of Gargantua itself. The clock will run slower than on Earth, but only by 20 percent. The stability of a planet close to a black hole, as shown in the film, is an impossible fantasy. In addition, it will be completely torn apart by the tidal forces of the black hole.
But on November 9, Plaint appears with a new article. He calls her Follow-Up: Interstellar Mea Culpa. The incomparable scientific critic decided to repent.
“I screwed up again. But no matter the magnitude of my mistakes, I always try to admit them. In the end, science itself forces us to admit our mistakes and learn from them!”
Phil Plaint admitted that he made mistakes in his thinking and came to the wrong conclusions:
“In my review, I talked about Miller's planet orbiting close to a black hole. An hour spent on the planet is equal to seven Earth years. My claim was that with such time dilation, a stable planetary orbit would be impossible.
And this is true... for a non-rotating black hole. My mistake was this. that I didn't use the correct equations for a black hole that was spinning fast! This greatly changes the picture of space-time near the black hole. Now I understand that a stable orbit of this planet around a black hole may well exist, and so close to the event horizon that the time dilation indicated in the film is possible. In general, I was wrong.
I also stated in my original analysis that gravitational tides would tear this planet apart. I consulted a couple of astrophysicists who also said that Gargantua's tides would probably destroy the planet, but this has not yet been mathematically confirmed. They are still working on solving this problem - and as soon as it is solved, I will publish the solution. I myself cannot say whether I was right or wrong in my analysis - and even if I was right, my considerations still only applied to a non-rotating black hole, so they do not apply to this case.
To solve such a problem, many mathematical problems need to be discussed. But I don't know exactly how far Miller's planet was from Gargantua, and so it's very difficult to say whether the tides would have destroyed it or not. I have not yet read the book by physicist and executive producer of the film Kip Thorne “The Science of Interstellar” - I think it will shed light on this problem.
However, I was wrong about the stability of the orbit - and I now consider it necessary to cancel this complaint about the film.
So, to summarize: the physical picture shown in the movie near a black hole is actually consistent with science. I made a mistake for which I apologize.
Ikjyot Singh Kohli, a theoretical physicist from Yor University, provided solutions to equations on his page, proving that the existence of Miller's planet is quite possible.
He found a solution in which the planet would exist under the conditions demonstrated in the film. But he also discussed the problem of tidal forces, which should supposedly tear the planet apart. His solution shows that tidal forces are too weak to tear it apart.
He even substantiated the presence of giant waves on the surface of the planet.
Singh Kohli's thoughts with examples of equations are here:
This is how Miller Thorne shows the location of the planet in his book:
There are points at which the orbit will not be stable. But Thorne also found a stable orbit:
Tidal forces do not tear the planet apart, but deform it:
If a planet rotates around a source of tidal forces, then they will constantly change their direction, deforming it differently at different points in the orbit. In one position, the planet will be flattened from east to west and elongated from north to south. At another point in the orbit it is compressed from north to south and stretched from east to west. Since Gargantua's gravity is very strong, the changing internal deformations and friction will heat the planet, making it very hot. But as we saw in the film, Miller's planet looks very different.
Therefore, it would be fair to assume that the planet always faces one side towards Gargantua. And this is natural for many bodies that rotate around a stronger gravitating object. For example, our Moon, many satellites of Jupiter and Saturn are always turned to the planet with only one side.
Thorne also made another important point:
“If you look at Miller’s planet from Mann’s planet, you can see how it revolves around Gargantua with an orbital period of 1.7 hours, covering almost a billion kilometers during this time. That's about half the speed of light! Due to time dilation for the Ranger crew, this period is reduced to a tenth of a second. It's very fast! And isn't that much faster than the speed of light? No, because in the reporting system of the vortex-like moving space around Gargantua, the planet moves slower than light.
In my scientific model of the film, the planet is always turned to the black hole with one side, and rotates at breakneck speed. Will centrifugal forces tear the planet apart due to this speed? No: she is saved again by the rotating vortex of space. The planet will not feel destructive centrifugal forces, since space itself rotates with it at the same speed."
6) How are such giant waves possible on the surface of Miller’s planet?
Thorne answers this question like this:
“I made the necessary physical calculations and found two possible scientific interpretations.
Both of these solutions require that the position of the planet's rotation axis be unstable. The planet should wobble in a certain range, as shown in the figure. This occurs under the influence of Gargantua's gravity.
When I calculated the period of this rocking, I got a value of about an hour. And this coincided with the time that Chris chose - who had not yet known about my scientific interpretation!
My second model is a tsunami. The tidal forces of Gargantua can deform the crust of Miller's planet, with the same period (1 hour). These deformations can create very strong earthquakes. They can cause tsunamis that will far exceed any ever seen on Earth."
7) How are such incredible maneuvers of Endurance and Ranger in Gargantua orbit possible?
1) Endurance is moving in a parking orbit with a radius equal to 10 times the radius of Gargantua, and the crew heading to Miller is moving at a speed of C/3. Miller's planet moves at 55% of C.
2) The Ranger must slow down from C/3 to lower the orbit and approach Miller Point. It slows down to c/4, and reaches the outskirts of the planet (of course, here you need to follow strict calculations to get there. But this is not a problem for the computer)
The mechanism for such a significant change in speed is described by Thorne:
“Stars and small black holes revolve around giant black holes, like Gargantua. It is they who can create the determining forces that will deviate the Ranger from his circular orbit and direct him down towards Gargantua. A similar gravity maneuver is often used by NASA in the solar system, although it uses the gravity of planets rather than a black hole. The details of this maneuver are not revealed in Interstellar, but the maneuver itself is mentioned when they talk about using a neutron star to slow down the speed."
A neutron star is shown by Thorne in the figure:
Date with a neutron star allows you to change the speed:
“Such an approach can be very dangerous, i.e. The ranger must get close enough to the neutron star (or small black hole) to feel strong gravity. If the braking star or black hole is with a radius smaller than 10,000 km, then the people and the Ranger will be torn apart by tidal forces. Therefore, a neutron star must be at least 10,000 km in size.
I discussed this issue with Nolan during production of the script, suggesting a choice of a black hole or a neutron star. Nolan chose a neutron star. Why? Because he didn’t want to confuse the audience with two black holes.”
“Black holes, called IMBH (Intermediate-Mass Black Holes), are ten thousand times smaller than Gargantua, but a thousand times heavier than ordinary black holes. Cooper needs such a diverter. Some IMBHs are believed to form in globular clusters, and some are found in the cores of galaxies, where giant black holes are found. The closest example is the Andromeda Nebula, the closest galaxy to us. Hidden in the core of Andromeda is a hole similar to Gargantua - approximately 100 million solar masses. When the IMBH passes through a region with a dense stellar population, the effect of “dynamic friction” slows down the speed of the IMBH, and it falls lower and lower, getting closer to the giant black hole. As a result, IMBH finds itself in close proximity to a supermassive black hole. Thus, nature could well have provided Cooper with such a source of gravitational deflection."
For a real-life application of the “gravitational slingshot,” see the example of interplanetary spacecraft, for example, check out the history of the Voyagers.
The recently released visually arresting film Inresttellar is based on real-life scientific concepts such as spinning black holes, wormholes and time dilation.
But if you are not familiar with these concepts, you may be a little confused while watching.
In the film, a team of space explorers embarks on an extragalactic journey through a wormhole. On the other side, they find themselves in a different solar system with a rotating black hole instead of a star.
They are in a race against space and time to complete their mission. This kind of space travel may seem a little confusing, but it is based on basic principles of physics.
Here are the top 5 physics concepts you need to know to understand Interstellar.
ARTIFICIAL GRAVITY
The biggest challenge we humans face during long-term space travel is weightlessness. We were born on Earth and our bodies have adapted to certain gravitational conditions, but when we are in space for a long time, our muscles begin to weaken.
The heroes in the movie Interstellar also face this problem.
To cope with this, scientists create artificial gravity in spacecraft. One way to do this is to spin up the spaceship, just like in the movie. The rotation creates a centrifugal force that pushes objects toward the outer walls of the ship. This repulsion is similar to gravity, only in the opposite direction.
This is a form of artificial gravity you experience when you are driving around a small radius curve and feel as if you are being pushed outward, away from the center point of the curve. In a spinning spaceship, the walls become your floor.
ROTATING BLACK HOLE IN SPACE
2
Astronomers have, albeit indirectly, observed rotating black holes in our Universe. Nobody knows what's at the center of a black hole, but scientists have a name for it: a singularity.
Rotating black holes distort the space around them differently than stationary black holes.
This distortion process is called "inertial frame entrainment" or the Lense-Thirring effect, and it affects how the black hole will look by distorting space, and more importantly the space-time around it. The black hole you see in the film is quite close to the scientific concept.
3
The spaceship Endurance is heading towards Gargantua, a fictional supermassive black hole 100 million times the mass of the Sun.
It is 10 billion light years away from Earth and has several planets orbiting it. Gargantua spins at an astonishing 99.8 percent of the speed of light.
Garagantua's accretion disk contains gas and dust with the temperature of the Sun's surface. The disk supplies the Gargantua planets with light and heat.
4
The complex appearance of the black hole in the film is due to the fact that the image of the accretion disk is distorted by gravitational lensing. Two arcs appear in the image: one formed above the black hole, and the other below it.
MOLE HOLE
5
The wormhole or wormhole used by the crew in Interstellar is one of the phenomena in the film that has not been proven to exist. It is hypothetical, but very convenient in the plots of science fiction stories where you need to overcome a large space distance.
It's just that wormholes are a kind of shortest path through space. Any object with mass creates a hole in space, which means space can be stretched, warped, and even folded.
A wormhole is like a fold in the fabric of space (and time) that connects two very distant regions, helping space travelers travel a long distance in a short period of time.
The official name for a wormhole is an “Einstein-Rosen bridge,” as it was first proposed by Albert Einstein and his colleague Nathan Rosen in 1935.
6
In 2D diagrams, the mouth of a wormhole is shown as a circle. However, if we could see the wormhole, it would look like a sphere.
On the surface of the sphere, a gravitationally distorted view of space on the other side of the “hole” would be visible.
The dimensions of the wormhole in the film: 2 km in diameter and the transfer distance is 10 billion light years.
GRAVITATIONAL TIME DELAYING
7
Gravitational time dilation is a real phenomenon observed on Earth. It arises because time is relative. This means that it flows differently for different coordinate systems.
When you are in a strong gravitational environment, time moves slower for you compared to people in a weak gravitational environment.
If you are near a black hole, as in the movie, your coordinate system, and therefore your perception of time, is different from that of someone on Earth. This is because the gravitational pull of a black hole is stronger the closer you are to it.
According to Einstein's equation, time moves slower in higher gravitational fields. The same thing happens on a planet close to a black hole: the clock ticks slower than on a spacecraft orbiting further away.
The presence of mass bends the membrane, like a rubber sheet.
If enough mass is concentrated at one point, a singularity is formed. Objects approaching the singularity pass through the event horizon, from which they never return.
To you, a minute near a black hole would last 60 seconds, but if you could look at a clock on Earth, a minute would last less than 60 seconds. This means that you will age slower than people on Earth, and the stronger the gravitational field you are in, the more time slows down.
This plays an important role in the film when explorers encounter a black hole at the center of another solar system.
In the film, intrepid explorers use a wormhole near the orbit of Saturn to enter another planetary system. The viewer is shown that a “wormhole” is a space-time tunnel through which people can almost instantly travel vast distances.
If you pierce a piece of paper - the imaginary Universe - at different ends, and then bend it so that the two holes are opposite each other, you will get that same wormhole.
But is instant travel between two distant points possible?
Professor Barstow:
I don't think wormholes really exist. This is something out of science fiction. There is no direct evidence of the existence of such things in the Universe. We know what black holes are, but we are just beginning to explore the possibility of space-time curvature.
Lee Billings:
I really hope that there are wormholes in space through which you can travel in five dimensions. But we have no idea whether stable wormholes exist on macroscopic scales. It seems that it is much easier to travel the old fashioned way without relying on a miracle; Perhaps solar sails will help in this matter. And there is no need to rush anywhere.
You can't survive if you fall into a black hole
In one of the key episodes of the film, one of the main characters, leaving a spaceship, falls into a black hole and then gets out of it. But is it possible to survive if you fall into a black hole?
No. The gravitational field of a black hole is extremely strong and changes very quickly. Everything that gets into it is stretched by gravity and becomes like long thin pasta. Therefore, anything that falls into a black hole has no chance of survival. It is also impossible to transmit signals from there.
Lee Billings:
Approaching the accretion disk around a supermassive black hole, as shown in the film, is a very bad idea. It is a big misconception that powerful radiation from hot material will allow it to slide along the event horizon and not melt. Habitable planets are also presented differently here.
Is it possible to go into orbit of a black hole?
The hero of the film uses the orbit of a black hole to get to one of the exoplanets. Is it possible?
You can orbit a black hole until you get very close to it. Astronomy shows us many systems in orbit around a black hole. And, as a rule, these are systems with stars. You can see them only if you are inside the event horizon.
If there are planets around a black hole, they are probably not suitable for life.
The researchers in the film visit a planetary system that is not only close to a black hole, but also has potentially habitable planets.
Nothing prevents planets from orbiting a black hole, although there are no such examples yet. The problem is the stability of such planetary systems. Any planetary system close to a black hole is likely to be consumed.
Lee Billings:
I think Interstellar is a film for physicists, not planetary scientists. There are many inconsistencies in the film related to the planets.
About the “easy singularity”
The hero of the film says that inside the black hole there is only a “light”, which can explain some of the events in the planetary system that the researchers are visiting. But is there even such a thing as an “easy singularity”?
The important thing is that black holes can have different masses. The singularity is the center of the black hole. But there is a concept that all black holes have a finite mass that does not disappear in space. This is how we actually detect them - the mass influences the surrounding material.
Matt Kaplan:
We know little about the processes near a black hole. Nobody knows what lies beyond the event horizon. For now we rely only on theory.
The aging process due to time dilation is shown accurately
Astronauts age much more slowly than their counterparts on Earth due to the effects of time dilation. According to the theory, people traveling at speeds close to the speed of light slow down time. There is experimental confirmation of this.
This is well known. Einstein's theory of relativity states that people traveling at different speeds experience time differently. For example, the astronauts who flew to the Moon aged slightly less than those who remained on Earth, although this was barely noticeable. But if you reach speeds close to the speed of light, which is quite difficult to do, the difference will be visible.
You can believe in artificial gravity on the space shuttle Endurance, but not in its fantastic engine
According to experts, the Endurance looked quite realistic. But the ease with which the spacecraft landed on and rose from the surface of the planets was considered implausible by them.
Lee Billings:
From the point of view of artificial gravity, which prevents the destruction of bones in zero gravity, Endurance looks quite plausible. Doubts are raised by the propulsion system, which made it possible to ignore the influence of the gravitational forces of the planets, as a result of which the astronauts aged ten years in an hour.
Matt Kaplan:
I think that for a story as big as this, some things can be overlooked.
It is known that the scientific consultant for the film was theoretical physicist Kip Thorne, a professor at the California Institute of Technology and a close friend of Stephen Hawking. Professor Thorne even wrote a book, “The Science of Interstellar,” in which he described some aspects of the film that were interesting to scientists.
But there are simpler stories in Interstellar that, when you look at them, make you want to say, “Hey, does this happen?” This review contains 14 facts that are of interest not only to physicists (spoilers!).
A solar-powered drone that lasts for decades
A similar device can be created. The Opportunity rover, for example, roamed the surface of Mars for more than 10 years, powered by solar energy. But Cooper's ability to hack it seems less likely - do all governments in the world use the same targeting program, accessed via Wi-Fi.
Verdict: plausible.
A black hole that looks like this
Supermassive black holes are among fairly common celestial bodies in our Universe. One of them is located in the center of our galaxy - the Milky Way, and almost all galaxies have black holes at their centers. The black hole simulation for the film was done by a group of university scientists led by Kip Thorne.
The light bending around the hole is not shown by chance. The black hole's gravity causes light rays to bend, so that an "Einshestein ring" is formed directly next to it. As we approached the hole, we would likely actually see light around it, as well as an accretion disk of matter being consumed by the black hole.
Verdict: plausible.
An artificial wormhole that looks like this
A wormhole or wormhole is a tunnel that allows passage through space and time to other parts of the universe. General relativity allows for their existence.
But you need to understand that it is impossible to create a wormhole without changes in our basic ideas about physics. In particular, you will have to use matter with negative mass, which is difficult to even imagine. Kip Thorne is one of the world's leading experts on wormholes, so his insights can be considered the most reliable source on the topic. At the same time, there is a lot we don't know. Will the altered structure of space-time tear apart the spaceship?
Verdict: plausible (for theory).
Time slows down on a planet orbiting a black hole
Gravity near massive objects distorts not only space, but also time. If we had sufficiently accurate measuring instruments, we would notice that time flows just a little slower on the surface of the Earth than on a tall tower. If the planet orbited the black hole so closely and did not break apart (we'll get to this later), then perhaps time would pass as slowly as it does in the film.
But a zone beyond which time dilation suddenly ceased to operate could not exist. The effect of gravity would disappear gradually.
Verdict: plausible.
The journey to Saturn takes two years
This is possible, although not with today's technology. The New Horizons spacecraft reached Saturn's orbit within two years, but it did not have the goal of reaching the planet's surface. A two-year journey would be possible if Endurance was designed specifically to be sent into a wormhole on a precisely calibrated course, otherwise it would require too advanced technology.
Verdict: possible, but not with today's technology.
The planet revolves around a black hole
This seems unlikely. Suppose a planet orbits rapidly around a black hole whose mass is one hundred times the mass of the Sun. It will be torn apart very quickly by tidal force - the difference in gravity on the outer and inner sides of the planet.
In addition, such a planet would be scorched by radiation and would suffer from collisions with other bodies attracted by the black hole. The planet could not have formed near a black hole, and even if it had been attracted by it, it would not have rotated in a stable orbit. We also need to remember that there would be no sunlight on it - the accretion disk produces a large amount of X-ray radiation, but not light.
And finally, if such a planet existed, landing and taking off a spacecraft would be practically impossible. Landing from the planet's orbit would require overcoming the gravity of the black hole - the ship would simply be torn from it and thrown beyond the event horizon, into the center of the hole. To take off, it would be necessary to reach a speed close to the speed of light.
Verdict: almost impossible.
There are huge waves on this planet
If the planet's mass is 130% that of Earth's and its surface is covered with water, wind waves will be no greater than waves in Earth's oceans. Tsunamis appear only as a result of tectonic activity and cannot be regular. The gravitational force of a black hole also does not explain them: the black hole would stretch the planet itself to the sides.
In the book The Science of Interstellar, Kip Thorne says that the waves arise from the movements of the planet itself. But we don't see currents in the film - so where does the extra water come from?
Verdict: as unlikely as the existence of the planet itself.
The Mysterious "Gravity Equation"
First of all, it is unclear exactly what equations we are talking about. The equations of general relativity are already known, so it can't be them. Most likely, this refers to the explanation of gravity through quantum mechanics, which string theory and loop quantum theory of gravity are trying to provide. At a minimum, this explanation will require many equations.
As for the way Professor Brand solves it: theoretical physics is done differently. You can’t sit for several years and make notes on a piece of paper. Why shouldn't he communicate with colleagues working in the same direction? Where are his graduate students? Why doesn't he have interns and students? The lonely scientist is a common but incorrect stereotype.
Verdict: far-fetched.
There are no plans to land on other planets
Space travel doesn't happen suddenly. In real life, all the contingencies that may occur along the way of a space mission would have been foreseen before sending it to Saturn. Yes, there was a rush when sending, but they had two years in the spacecraft and the opportunity to consult with scientists on Earth.
Verdict: poorly thought out.
The Universe has a fifth dimension
If the world had an extra dimension, it is quite possible that gravity would be due to it. It could be used to explain time travel. But we have no evidence of other dimensions.
Verdict: too speculative.
Frozen clouds of the planet
Ice is too heavy to become material for a cloud. And Kip Thorne knows it. In an interview with Science magazine, he said: "Every time I watch the movie, this is the only place where I cringe."
Verdict: cute, but impossible.
Collecting 'quantum data' from a black hole
Everything that is close enough to the black hole will be destroyed and turn into a kind of spaghetti (“spaghettification effect”). Get quantum data? No. This is a black hole.
Verdict: and here is the reason to send the main character into a black hole.
Someone jumps into a black hole...
Bad plan. Very bad. First, spaghettification. Secondly, there is no connection. Everything that is beyond the event horizon moves in one direction - the singularity point.
Verdict: really bad idea.
... and ends up in a place that is not in a black hole
Strictly speaking, general relativity allows that after falling into a black hole, you can end up somewhere else (but the journey will definitely be unpleasant). And there may be powerful aliens who have mastered the force of gravity.
Verdict: Before you jump, make an agreement with the aliens.
Once on the far side of the wormhole, the spacecraft enters a three-planet system orbiting a supermassive black hole that researchers call Gargantua. Supermassive black holes, with masses ranging from a million to several billion solar masses, are believed to reside in the cores of all galaxies. It is likely that in the center of our Milky Way there is such an object - Sagittarius A, whose mass exceeds 4 million solar masses (4.31 106 M;). According to Thorne, Gargantua is more likely to be similar to the even more massive supermassive black hole that is believed to be at the core of the Andromeda nebula, which is estimated at 100 million solar masses (1.1–2.3; 108 M;). Its size is approximately proportional to its mass, and the radius of such a giant would cover the Earth's orbit around the Sun.
Such huge black holes are not a fantastic exaggeration, since we have observational data confirming the existence of such “monstrous” black holes in distant galaxies (Behemoth). The largest black hole discovered so far is in the galaxy NGC 1277, located 250 million light years away. Its mass can be estimated at 17 billion solar, and its size is comparable to the orbit of Neptune.
Another important characteristic of Gargantua is that it is a rapidly spinning black hole. All objects in the Universe, excluding the Universe itself, tend to rotate. Naturally, black holes also rotate, which is described by Kerr geometry. The latter depends on two parameters: the mass of the black hole (M) and the angular momentum (J). An important difference from ordinary stars, which rotate differently, is that black holes, according to Kerr, rotate with unusual stability: all points on its conventional surface (event horizon) rotate with the same angular velocity. However, there is a limiting angular momentum Jmax above which the event horizon will disappear: this limitation corresponds to the fact that the rotation speed of the horizon will be equal to the speed of light. In such a black hole, called an “extreme” black hole, the gravitational field at the event horizon will disappear because the internal influence of gravity will be compensated by the huge repulsive centrifugal forces. However, it is quite possible that most black holes in the Universe have angular momentum quite close to the limiting one. For example, a typical stellar-mass (about 3 solar mass) black hole considered to be the driving mechanism in binary X-ray sources would spin at 5000 revolutions per second. Presumably, the Gargantua black hole shown in Interstellar has an angular momentum 10 to the -10th power close to the limiting Jmax. Even if this is theoretically possible, this configuration still seems unrealistic from a physical point of view. Because the faster a black hole rotates, the harder it is to drag along matter rotating in the same direction under the influence of centrifugal forces, while matter rotating in the opposite direction is easily “sucked” into the black hole, slowing down the rotation. As a consequence, a black hole spinning too quickly will tend to slow down to an equilibrium speed less than that of Gargantua (according to relativistic general calculations, black holes should spin no faster than 0.998 Jmax). However, the advantage of very fast spinning black holes is that planets can orbit very close to the event horizon without falling under it. This is a key point in the film and also allows for very strong time dilation.
For a Schwarzschild black hole (that is, for a hole with angular momentum J=0), the stable inner circular orbit in which any object will spiral and crash into the black hole is located at a distance of three radii of the black hole itself. For a black hole with a mass equal to 100 million solar masses, this distance would be about 900 million kilometers, slightly more than the distance from Jupiter to the Sun. But for a Kerr black hole orbiting very close to the limiting Jmax, a stable inner circular orbit could be as close as the event horizon itself, only 100 million kilometers. This explains why in Interstellar, Miller's planet can orbit just above the event horizon without falling.
It's also worth noting that the Kerr black hole is not a top spinning in stationary outer space; rotating, it holds the entire canvas of space-time along with itself. As a consequence, Miller's planet should rotate at a speed close to that of light.
