QuestionWhat happens when you throw a camera into a black hole?
Hopes&Fears answers questions with the help of people who know what they are talking about. We ask NASA, theoretical physicists and science-fiction writers about the fate of a camera in a black hole.
Partially inspired by a conversation about Christopher Nolan’s film Interstellar, we wondered what it’d be like to actually go through a black hole. Has anyone ever tried sending a camera through a black hole? Can any of that information (the pictures) be retrieved? What would we see? We talked to astrophysicists, theoretical physicists, NASA scientists, and science-fiction writers to get the answers.
a scientist and engineer at the NASA John Glenn Research Center, and an acclaimed hard science-fiction writer
A far too simple answer, I'm afraid.
You can send a camera into a black hole, but, according to the classical theory of general relativity, you will only get information back from it until it passes through the event horizon. Up until it crosses the event horizon, you could use a radio link to send images. The camera will experience tidal forces, which will try to stretch it out, but if the black hole is large enough—thousands of solar masses, say—the camera should easily survive. From the camera's point of view, nothing exciting happens as it passes the event horizon... but from the point of view of an observer watching from outside the black hole, the radio link receiving the pictures from the camera will be shifting to lower and lower frequencies, and the pictures will be slower and slower to receive, until the very final picture takes literally an infinite time to come down, and comes down at a radio frequency that is stretched to an infinitely long wavelength.
If the black hole is spinning, it's more complicated. A spinning black hole has two different event horizons, an inner one and an outer one, and if you are clever enough, you can still send information out even after you pass the outer event horizon. The inner event horizon, however, is still a one-way trip-- you can drop the camera in, but won't get any information out.
Unless there's a wormhole inside. But that's a different story.
Sizes of black holes
1.6 light years
1.6 million light
61 light years across
(a few million Earths)
A sugar-cube-size fragment of a neutron star would weigh a billion tons on Earth
A neutron star’s gravitational pull is so severe that if you were to drop a marshmallow on it, the impact would generate as much energy as an atom bomb
Stephen Hawking lost a bet—originally placed in 1974—that Cygnus X-1 did not contain a black hole.
Einstein thought black holes were too preposterous to be real.
NASA consultant, scientist, and science-fiction writer
You ask the classic question—if anything lies beyond the event horizon of a black hole, might we ever discover what it is? Our contemporary physics suggest the answer is 'no.' That even in theory, information cannot pass outward across that horizon. Yet, something within us deems every "horizon" to be a challenge. An opportunity to explore, even if only via literature of the imagination.
Hence, in Christopher Nolan's film Interstellar, one astronaut finds a realm just within the event horizon—a place where time is fluid and navigable, where distant human descendants offer him glimpses, revelations and opportunities. My own story "What Continues..." is a thought experiment in which two women scientists drop cameras through a black hole to spy on the "daughter universe" within.
According to physicist Lee Smolin, our own cosmos might have erupted that way, from a black hole created within a previous, mother universe. And that mother appeared the same way, each cosmos spawning billions of new ones, with Black Holes serving as eggs—or fetuses. The implications of Smolin's concept are amazing.
Mass of black holes
4.5 million suns
(micro-quasar containing a black hole)
14 times the sun
14.8 times the mass of the sun
For a star 20 times the mass of the sun, the energy released in its final moment of collapse far exceeds that released if you detonate a Hiroshima-like bomb every millisecond for the entire life of the universe.
Hunks of iron bigger than Mount Everest are compacted instantly into grains of sand.
Professor of Physics at UCSB's Department of Physics, and a member of the Kavli Institute for Theoretical Physics
The short answer here is no. The word through implies that the camera would go in and then come out. But nothing—astronaut, camera, light—can get out of a black hole. Einstein's theory tells us what the inside should look like, a space that becomes more and more curved as we fall toward the singularity, crushing us before we get there. (Actually, we get squeezed in some directions and stretched in others, so it is called 'spaghettifying.') We tend to trust what Einstein's theory tells us, because it works very well on things that we can see, but we would have to jump in to find out and would be crushed (or spaghettified) shortly after getting the answer.
Nevertheless, it is interesting to think about the inside of black holes so as to understand the limits of Einstein's theory. In fact, there are arguments from quantum mechanics that Einstein's theory fails inside a black hole. Most physicists don't believe this, but it is an interesting puzzle.
Passing of time near black holes versus time on Earth
If you got close to Sgr A*, for every minute you spend there, a thousand years will pass on Earth.
If you cross the event horizon of, say, Sagittarius A*, the person watching from the outside will not see you fall in. You will appear frozen at the hole’s edge, for an infinite amount of time.
If the Earth would become a black hole
It would retain its current weight of more than six sextillion tons (6,000,000,000,000,000,000,000 tons), but be shrunk in size to smaller than an eyeball and the Moon wouldn't move.
Approximate size of the Earth if it collapsed into a black hole: 0.7 inches.
Theoretical Physicist at the Institute for Advanced Study in Princeton, NJ
You can send anything into a black hole. You can send a camera.
But neither the camera, nor any signal from it, would be visible from the outside.
According to Einstein theory you cannot get any signals from the interior in any way. One should think of the interior as being to the future of everything outside. We cannot get any signals for the same reason that we do not get any signals from the future.
As the camera gets close to the black hole horizon you would see that its transmition gets slower and slower, so slow that at some point the signals from the camera get overwhelmed by the Hawking radiation coming out from the black hole. Though, in the real world, the signals would be overwhelmed earlier by the cosmic microwave background radiation.
Spin rate of black holes
over half the speed of light
more than 600 times/second
To overcome Earth’s gravity, you must accelerate to about 7 miles/second—this is 6x faster than a bullet.
Universal speed limit is 186,282 miles/second—the speed of light. It is still not enough to overcome the clutches of the black hole.
Temperatures reach 100 billion degrees inside black holes.
Human-built rockets have been achieving escapevelocity since 1959.
Physicist at UC Santa Barbara
According to Einstein’s theory of relativity, there is no problem sending a camera (or anything else) into a black hole (meaning that it goes in past the horizon). Getting it (or its photographs) back out is an entirely different issue. This is not possible.
Science Fiction author of The Ophiuchi Hotline (1977) and "The Black Hole Passes" (The Persistence of Vision, 1978)
According to my bare bones understanding, you can send a camera into a black hole. You can send anything into a black hole, it will eat it all. The problem is in getting either the camera or any information it records back out of the hole. Nothing comes out except something called Hawking radiation, which has something to do with quantum theory. For all practical purposes, once something crosses the event horizon, it's gone, right out of our universe.
There are more than 100 billion galaxies in the universe.
In a neighboring galaxy, Andromeda, there’s a black hole with as much mass as 100 million suns.
Other galaxies are thought to contain billion-sun black holes, and some even ten-billion-sun black holes.
American science fiction author: A Hole in Space (1974), Tales of Unknown Space (1975), World Out of Time (1976)
You can send the camera. It won’t send anything back. In a standard black hole, it will be crushed. In a rotating black hole, it could come out somewhere else. It probably still won’t send anything back.
Research Fellow at Harvard's Center for the Fundamental Laws of Nature, Harvard University High Energy Theory Group
The direct answer to your question is that yes, a camera can pass through a black hole just like any other piece of matter.
Even this answer though depends on the reference frame of the observer witnessing the camera going into the black hole. This is called black hole complementarity; it's the conjecture that two distinct events will be observed, depending on the observer's reference frame. More specifically, the camera would observe—or actually, an observer in the infalling frame with the camera would observe—that it passes the event horizon without any drama. (This also assumes that the black hole is sufficiently massive that tidal forces aren't an issue at the horizon.) A distant observer (someone sufficiently far away from the black hole), on the other hand, would observe the camera (well, its energy and information) getting absorbed by and dissipated throughout a membrane just outside the event horizon of the black hole. This membrane consists of all the matter that would have gone into the black hole and exists right outside the event horizon because this is where all the would-be infalling matter aggregates according to a distant observer's perspective.
This all also assumes that there doesn't exist a firewall at the horizon of the black hole. Firewalls are arbitrarily high-energy modes that are excited at the black hole's horizon and don't allow anything to pass. There is debate within the physics community as to the reality of firewalls (as there also is with black hole complementarity, but even more so with firewalls), so I'm not considering them in my response.
Now, if you then asked if you could ever send information (e.g. pictures) from the camera to someone outside the black hole, the answer would be no (sort of). Classically (according to general relativity), no signal can cross the event horizon from the interior of a black hole. When understood from a more modern perspective though (i.e. one accounting for quantum mechanics and potentially string theory), it is thought that all the quantum information that enters a black hole eventually exits the horizon as Hawking radiation. This information would be in a scrambled state, encoded in the correlations among all the Hawking particles. To distil this radiation to uncover any bits of information that had entered the black hole would be a very complex computation though and would require a very long time (even for a quantum computer).
event horizon: the area around a singularity where nothing—including light—is able to escape; "event horizon—the point of no return for material falling towards a black hole”
Hawking radiation: black holes leak. The seepage is called Hawking radiation. Given enough time, this radiation will evaporate entirely. We’re talking about trillions upon trillions upon many more trillions of years.
singularity: the material leftover after the explosion of a star falls into an infinitely small point, called the singularity
stellar black holes are made when the center of a very big star falls in upon itself, or collapses. When this happens, it causes a supernova, "a class of black holes that comes from the collapse of a massive star.”
supernova: an exploding star that blasts part of the star into space.
magnetar: dense, collapsed stars (called "neutron stars") that possess enormously powerful magnetic fields.
globular clusters, the ancient concentrations of stars distributed in a spherical pattern about the center of the galaxy.
Black Hole Sun
After burning through the last of its hydrogen fuel in about five billion years, the outer layers of the sun will drift away. The sun’s core will compact to become a white dwarf, “an Earth-size ember of the cosmos.”
It would retain the same mass, but its diameter would shrink from 865,000 miles to less than four miles. Earth would become dark and cold, but our orbit around the sun wouldn’t change.
This black hole sun would exert the same gravitational pull on Earth as the full-size sun.
The jets of black holes can extend for millions of light-years, drilling straight through the galaxy.