# The speed of light is 299,792,458 m/s, what is the speed of darkness?

GizAsk column – ask Gizmodo newspaper anything related to science, they will … go ask other experts in the industry to answer questions that readers have . The questions of humanity are inherently difficult to solve, and most of us can hardly find the answer despite spending many hours of Google continuously.

The question this time is a bit “dark”…

The speed of light is still one of the most important constants in physics, and since light has existed since the dawn of time, philosophers and scientists from time immemorial have made certain observations about it. light: Aristotle and Empedocles long ago disagreed; Aristotle believed that light had the ability to travel instantaneously, and the Greek scientist Empedocles suggested that because light moves, it must have taken time to travel between two points.

Light will travel at a fixed speed, no matter how fast the observer moves.

In 1667, Galileo Galilei stood from the top of a hill, observing the speed at which a covered lantern was opened in the hands of his fellow experimenters, trying to calculate the speed of light. They stood less than a mile (1.6 km) apart so it was too hard to tell the difference. Galileo only estimated that the speed of light is 10 times faster than sound.

It was not until the 1670s that astronomer Ole Rømer relied on the eclipse of Jupiter’s moon to calculate the speed of light. He found that light takes a certain amount of time to reach Earth, observing that eclipses are slow when Jupiter is farthest from Earth, and very punctual when Earth and Jupiter are close. each other more.

That’s why Rømer believed that ” light moves through the universe at a certain speed “, and then gave the estimate that light takes about 10-11 minutes from the Sun to reach the Earth. Although the above number deviates from the actual number (8 minutes 19 seconds), scientists still have an important number to conduct research. At that time, Römer calculated the speed of light to be 200,000 km/s.

Ole Rømer, one of the most important names in physics.

The speed of light passed through the heads of a host of eminent scientists, such as Hippolyte Fizeau and Léon Foucault from France, Albert Michelson the Prussian American, and when Albert Einstein began writing scientific reports on it in 1905 , the speed of light was accompanied by a concept few people thought of at the time – special relativity. He postulated that light would travel at a fixed speed, no matter how fast the observer was moving.

The world of science discriminates against gloom but doesn’t see any work that shows the speed of darkness? Gizmodo asked a bunch of experts on black holes and quantum physics, and got very interesting answers.

Editors of two leading scientific journals, Scientific American and Nautilus, author of Bizarre Activity at a Distance: Events that Redefine Space and Time – and What It Means for Black Holes, The Big Bang and Theory of Everything, and The Fool’s Guide to String Theory.

The speed of the night? The simple answer is that it is the speed of light. Turn off the Sun, the Earth will also darken after 8 minutes. But it’s boring as simple as that! First, what we’re used to calling “the speed of light” is actually the speed of propagation , and it’s not always what determines the final speed figure. For example, as the light on the lighthouse’s roof rotates, the speed of the shadow it casts on the ground increases as it moves further away from the lighthouse.

If the light from the lighthouse were to hit you directly at 12 o’clock, you’d see the light flash slowly.

If you stand far enough from the lighthouse, its shadow will glide over your head even faster than the speed of light (in the Universe, neutron stars are proof of this phenomenon). In the above cases, the speed of light has its own delay: if the light from the lighthouse were to hit you at exactly 12 o’clock, you would see the flash of light slow down a bit. However, the speed of things happening at the point where you stand does not change.

By the way, does darkness really exist? If the Sun can be turned off, the Earth will not be in eternal darkness. Light from stars, from nebulae, from explosions in space will fill the sky. This planet and everything on it, including our bodies, emits infrared light. It is up to the Sun to be turned off to see how it will continue to shine. Humans have eyesight, we will still be able to see something. No light-receiving mechanism can determine a completely black shadow, because if nothing emits a light source, quantum oscillations also produce light. Even black holes, the blackest objects we know of, emit their own light. Physics is far from real life, light always dispels darkness.

Darkness does not belong to the physical category, but more like a state of awareness. Whether the photon hits our eyes, does the cell located on the retina record light to stimulate the brain to create images, does not explain how the brain perceives darkness, it is as mysterious as The length of the wavelength represents the perception of color and sound. The experience of human consciousness changes with time, but the nature of those experiences is not affected by time. In this sense, darkness has no speed.

Director of the Hayden Planetarium, associate director of research and founder of the Department of Astrophysics at the Natural History Museum, is the host of Cosmos: The Adventures of Spacetime.

The speed of the night… Let’s think of the light as dispelling the darkness. The speed at which light dispels darkness is the speed of light, so the speed of darkness will be a negative number of the speed of light . If light is a vector, with direction and magnitude, then its negative number will have a negative square. The darkness dissipates at a faster rate than it spreads, I will call it the speed of negative light.

Director at California Institute of Technology LIGO Laboratory

Basically, the speed of darkness depends on two things, either you are the matter swallowed up by the endless darkness of the black hole, or you stand far enough away to watch something fall into the eternal black hole. If you are the unlucky matter falling into a black hole, the speed will certainly be very high, equivalent to the speed of light.

If you were an observer and were far enough away to witness the event, the rate at which matter was swallowed up by the black hole would be greatly slowed, due to an effect known as time dilation due to gravity – clocks run much slower when standing in a large gravitational field, and slower near the black hole’s event horizon.

“From far enough” means your position relative to the black hole, far enough away for you and the watch you carry without being affected by the black hole’s gravity. In fact, for a person watching from afar, it would take an infinite amount of time to witness something drift into the black hole’s event horizon.

Researcher at the Leonard E. Parker Center for Gravity, Cosmology, and Physics, at the University of Wisconsin-Milwaukee.

The gravity of a black hole is so strong that even light cannot escape its event horizon. It is because of the strong gravitational force that time dilation will affect observations made from outside this strong gravitational field.

For example, a person standing from a distance watching a luminous object fall into a black hole, they will see it slowly fall and gradually disappear, then there will come a time when we do not see the small bright dot present anymore. This observer will not be able to see the other over the event horizon.

We can also see from the perspective of the object itself falling into the black hole. For example, if a star is crushed when it accidentally encounters a black hole, the gas from that star will form a large accretion disk that surrounds the black hole and is slowly sucked in. But the entry of matter from the star into the black hole does not happen instantaneously.

There is a certain speed limit, caused by radiating pressure from within the hot gas, which will counteract the black hole’s gravitational pull in matter. As the black hole swallows the star, its size will increase. If a black hole 10 times the size of the Sun were absorbing the accretion disk at the highest possible rate, in about 1 billion years, the black hole’s mass would be 100 million times that of the Sun.

Assistant Professor of Gravity Astrophysics in the Department of Physics and Astronomy at the University of Waterloo, and teaching staff in the Department of Cosmology and Gravity at the Perimeter Institute for Theoretical Physics.

I believe that the “speed of the night” is endless! In classical physics, black space could simply be a vacuum of nothing. However, quantum mechanics tells us that there is no absolute darkness in space. Even if an area without light allows us to observe it, the magnetic field of matter particles can appear at any time, even for a moment. Even gravitational waves, the recently discovered spacetime background vibration phenomenon, carry these quantum oscillations.

Gravitational wave illustration.

The conundrum is that the gravity of these quantum vibrations is infinite. In other words, we haven’t come up with a theory that explains quantum gravity. One of the ways to avoid this problem, is if the “dark speed” – that is, the quantum vibrations – reaches the limit of infinity on a small scale and in a short time.

That’s just one possibility, but it’s still the simplest (and my favorite) way to understand the big bang, black holes, dark energy, and quantum gravity.