The speed of light is one of the most important constants in physics. The Danish astronomer Olaf Roemer first estimated the speed of light in 1676. However, the scientist who established that it was light that sets the upper limit of the attainable speed in our Universe, equal to almost 300,000 kilometers per second, was precisely Albert Einstein. And yet, according to the same Einstein theory, everything in this universe is relative, including motion. This, in turn, forces us to ask a completely logical question: what is the speed of the complete opposite of light - darkness?
We are far from the first to ask this question, but the Gizmodo portal decided to delve deeper into it and on this occasion turned to one of the most respected and famous scientists, researchers, theorists, experts on black holes and quantum physics. Interestingly, they all have no consensus on this matter. Some believe that darkness can have the same speed as light. Others believe that it can be infinitely slower. Still others are sure that everything will depend on the point of view from which you look at this issue.
George Masser
Editor of Scientific American and Nautilus magazines, author of Creepy Action at Distance: A Phenomenon Redefining Space and Time. Significance of the Phenomenon in Black Hole Theory, The Big Bang Theory and The Theory of Everything, as well as The Complete Guide to String Theory for Idiots
“The speed of darkness? The simplest answer is that the speed of darkness is equal to the speed of light. Turn off the Sun and our sky will go dark eight minutes after this point. But that's a boring answer! No, really! First, what we used to call the "speed of light" is the speed of propagation, and this is not always the decisive factor. A shadow falling on a landscape is cast by objects. And the peculiarity of these objects, as well as the distance from them, will determine how fast it will fall.
For example, a rotating beacon spotlight illuminates its surroundings at regular intervals. However, the relative speed of obscuration of the environment increases with increasing distance to the lighthouse itself. If you move far enough from the lighthouse, then the shadow will overtake you faster than the speed of light. The same thing happens, for example, with neutron stars in space. In other words, in this case, the speed of light will only mean a delay. Even if the beacon is aimed directly at you, you will not see the light immediately, but with some delay. However, this will not in any way affect the course of events that you will see, being in your place.
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But is there even such a thing as darkness? More precisely, there is a concept, but is there a phenomenon itself? Even if you "turn off" the Sun, the Earth will not plunge into complete impenetrable darkness. Light from stars, nebulae and even the Big Bang itself will illuminate your sky in this case. The planet itself and everything on it, including our bodies, also emit light. And it will be visible in the infrared. Even if you somehow found a way to “turn off” the Sun, even then it will emit a certain level of glow almost forever. For your century and for many centuries to come, there will be enough for sure. That is, as long as we have the opportunity to see, we will see. No optical sensor is able to detect complete darkness, because even if there are no light sources nearby,the available quantum fluctuations will also produce very light flashes of light. Or take black holes - the darkest of the alleged objects. Even they are capable of emitting a certain percentage of light, according to some theories. In physics, in contrast to the sphere of interpersonal relations, light always "conquers" darkness.
Darkness is not a physical category, but rather a relative state. Not even that. This is a subjective perception of the state. Photons may or may not be reflected, retinal cells can trigger memory processes, but they cannot explain the subjective sensation of darkness, just as waves cannot be represented by anything more than our experience of observing color or sound. Our subjective experience changes from time to time, but individual parts of this experience lie outside of time. And in this sense, we can say that the darkness itself does not have speed.
What is speed in the general sense? And does it exist at all? It presupposes the presence of a certain space in which it can be measured. However, many scientists working with quantum physics - a world where the usual concepts of ordinary physics often become useless - believe that space itself is one of the derivatives of a more fundamental level of reality, where there are no such concepts as position, distance or the same speed.
Avi Loeb
Professor of Astrophysics at Harvard University, founder of the Black Hole Initiative (BHI)
“Matter attracted to the center of the black hole reaches a speed close to the speed of light. Anything that falls within the so-called black hole event horizon has no way to escape. Even light is forever sealed within the event horizon. With this in mind, black holes can be viewed as some kind of prisons of eternal darkness. But this is not the case.
A star like the Sun can be spaghettized into a stream of gas if it passes next to a massive black hole, such as the one in the center of our Milky Way galaxy, whose mass is 6 billion solar masses.
However, when falling into a black hole, matter can create friction with each other and heat up. The end result of this friction is radiation. If the rate of accretion (the process of mass increment) is high enough, then the pressure of the outgoing radiation will potentially be able to save additional surrounding matter from falling. Many of the most massive black holes in the Universe, with the mass of billions of suns, have the highest possible accretion rates."
Neil DeGrasse Tyson
Astrophysicist, Ph. D. in physics, writer, popularizer of science, director of the Hayden Planetarium at the American Museum of Natural History in Manhattan. Host of the popular science series "Space: Space and Time"
“The speed of darkness means … Considering that darkness itself is the result of the cessation of light? If the speed of light is represented by a constant, then the speed of darkness will be the exact opposite constant of the speed of light. If light is a vector, it has magnitude and direction, then … speaking of its negative value, we will talk about its opposite direction. The darkness in this case is the opposite direction, not the direct one. I would say that darkness has the opposite negative value for the speed of light."
Sara Caudill
PhD from the Leonard E. Parker Center for the Study of Gravity, Cosmology, and Astrophysics, University of Wisconsin-Milwaukee
“The gravitational force of black holes is so great that even light cannot escape it once it enters the radius of its event horizon - invisible boundaries that create a point of no return. Since black holes have such a strong gravity, observations made outside this strong gravitational field will be influenced by the effect of time dilation.
Suppose that far from the black hole there is an outside observer who sees a luminous object falling into the black hole. From the point of view of the observer, this luminous object will first slow down its speed, and then "go out", becoming so dim that it will be impossible to see it. The observer will not even be able to see how the object crosses the border of the event horizon.
If we look at the situation from the point of view of matter falling into this black hole. Imagine now a black hole surrounded by a cloud of glowing gas. This cloud was formed by a star torn apart, passing too close to this black hole. This gas cloud will appear as a flattened disk, also called an accretion disk. So, the gas of this disk will eventually be completely absorbed by the black hole, but this will not happen immediately.
The fact is that there is a speed limit that depends on the force of the radiation pressure of the heated gas, which will resist the action of the internal force of gravity of the black hole itself. Ultimately, as soon as all the gas is absorbed by the black hole, its size will increase. For example, if we take a black hole, whose initial mass will be 10 times the mass of our Sun, and the rate of its mass accretion will reach its maximum limit (the so-called Eddington limit), then in about a billion years the mass of this black hole will reach a mass of 100 million times exceeding the mass of our Sun”.
David Reice
Scientific Supervisor of the Laser Interferometric Gravitational Wave Observatory (LIGO)
“Basically, everything will depend on whether you are the matter that is absorbed by the endless abyss of a black hole, or you are far enough from the scene and are an impassive observer of the event of someone or something else falling into this very abyss. If you are unlucky and you are in the first place, then the speed will be very high. Most likely, we will talk about indicators close to the speed of light.
If you find yourself in the place of the second and are far enough from the black hole, then the speed with which matter will be absorbed by the black hole will seem to you noticeably reduced due to the effect of gravitational time dilation. According to him, the "clock" under the influence of the gravitational field goes slower, and under the influence of a very strong gravitational field - even slower, which will be true just with the approach to the event horizon of the black hole.
By far enough I mean that in your local coordinate system you will remain stationary relative to the black hole (that is, you will not be attracted into it) and your local time system will not be influenced by the gravitational field of this black hole. In this case, for a person outside the influence of the black hole, it will seem that the object or matter will move towards the event horizon of the black hole for an infinitely long time.
Nyayesh Afshordi
Astrophysicist in the Department of Physics and Astronomy at the University of Waterloo and Head of the Department of Cosmology and Gravity at the Perimeter Institute for Theoretical Physics in Canada
“I believe that the speed of 'darkness' is infinite! In classical physics, under the general concept of the darkness of space, just an empty vacuum can be considered. However, thanks to quantum mechanics, we know that in fact no darkness and empty space exist. Even if it seems to you that there are no sources of light that we could see, this source can be fluctuations of electromagnetic fields. Even within the gravitational waves cutting through space-time and discovered by the LIGO laboratory only recently, these quantum fluctuations must be present.
The problem is that the level of gravity in this quantum ripple is infinite. In other words, there is currently no compelling theory of quantum gravity that most scientists would agree with. The necessary answer to the question may be hidden in the very possibility of the speed of "darkness", that is, the quantum ripples reach an infinite value (or become arbitrarily large), especially on a small scale and for a short period of time. Of course, this is just an assumption, but it seems to me that this is an effective way to understand the principle and essence of the Big Bang, black holes, dark energy and quantum gravity."
NIKOLAY KHIZHNYAK
