Many of us have heard of Stephen Hawk­ing but know him only as a sym­bol of a pow­er­ful mind ded­i­cat­ed for a life­time to the thorni­est prob­lems in astro­physics. Even more of us have heard of black holes but know of them only as those dan­ger­ous things in sci-fi movies that suck in space­ships. But if we gain an under­stand­ing of Hawk­ing’s work on black holes, how­ev­er basic, we gain a much clear­er view of both enti­ties and what they mean to the human endeav­or of grasp­ing the work­ings of real­i­ty. What it all has to do with “one of the biggest para­dox­es in the uni­verse,” and why that para­dox “threat­ens to unrav­el mod­ern sci­ence,” pro­vide the sub­ject mat­ter for the ani­mat­ed TED-Ed les­son above.

In order to explain what’s called the “Black Hole Infor­ma­tion Para­dox,” astro­physi­cist Fabio Pacuc­ci must first explain “infor­ma­tion,” which in this usage con­sti­tutes every part of the real­i­ty in which we live. “Typ­i­cal­ly, the infor­ma­tion we talk about is vis­i­ble to the naked eye,” he says. “This kind of infor­ma­tion tells us that an apple is red, round, and shiny.” But what physi­cists care about is “quan­tum infor­ma­tion,” which “refers to the quan­tum prop­er­ties of all the par­ti­cles that make up that apple, such as their posi­tion, veloc­i­ty and spin.” The par­ti­cles that make up every object of the uni­verse have “unique quan­tum prop­er­ties,” and the laws of physics as cur­rent­ly under­stood hold that “the total amount of quan­tum infor­ma­tion in the uni­verse must be con­served.”

Smash the apple into sauce, in oth­er words, and you don’t cre­ate or destroy any quan­tum infor­ma­tion, you just move it around. But in the parts of space­time with grav­i­ty so strong that noth­ing can escape them, bet­ter known as black holes, that par­tic­u­lar law of physics may not apply. “When an apple enters a black hole, it seems as though it leaves the uni­verse, and all its quan­tum infor­ma­tion becomes irre­triev­ably lost,” says Pacuc­ci. “How­ev­er, this doesn’t imme­di­ate­ly break the laws of physics. The infor­ma­tion is out of sight, but it might still exist with­in the black hole’s mys­te­ri­ous void.”

Then we have Hawk­ing Radi­a­tion, the epony­mous genius’ con­tri­bu­tion to the study of black holes, which shows that “black holes are grad­u­al­ly evap­o­rat­ing,” los­ing mass over “incred­i­bly long peri­ods of time” in such a way that sug­gests that “a black hole and all the quan­tum infor­ma­tion it con­tains could be com­plete­ly erased” in the process. What might go into the black hole as an apple’s infor­ma­tion does­n’t come out look­ing like an apple’s infor­ma­tion. Quan­tum infor­ma­tion seems to be destroyed by black holes, yet every­thing else about quan­tum infor­ma­tion tells us it can’t be destroyed: like any para­dox, or con­tra­dic­tion between two known or prob­a­ble truths, “the destruc­tion of infor­ma­tion would force us to rewrite some of our most fun­da­men­tal sci­en­tif­ic par­a­digms.”

But for a sci­en­tist in the Hawk­ing mold, this dif­fi­cul­ty just makes the chase for knowl­edge more inter­est­ing. Pacuc­ci cites a few hypothe­ses: that “infor­ma­tion actu­al­ly is encod­ed in the escap­ing radi­a­tion, in some way we can’t yet under­stand,” that “the para­dox is just a mis­un­der­stand­ing of how gen­er­al rel­a­tiv­i­ty and quan­tum field the­o­ry inter­act, that “a solu­tion to this and many oth­er para­dox­es will come nat­u­ral­ly with a ‘uni­fied the­o­ry of every­thing,’ ” and most bold­ly that, because “the 2D sur­face of an event hori­zon” — the inescapable edge of a black hole — “can store quan­tum infor­ma­tion,” the bound­ary of the observ­able uni­verse “is also a 2D sur­face encod­ed with infor­ma­tion about real, 3D objects,” imply­ing that “real­i­ty as we know it is just a holo­graph­ic pro­jec­tion of that infor­ma­tion.” Big if true, as they say, but as Hawk­ing seems to have known, the truth about our real­i­ty is sure­ly big­ger than any of us can yet imag­ine.

via Brain Pick­ings

Relat­ed Con­tent:

Stephen Hawking’s Final Book and Sci­en­tif­ic Paper Just Got Pub­lished: Brief Answers to the Big Ques­tions and “Infor­ma­tion Para­dox”

Stephen Hawking’s Lec­tures on Black Holes Now Ful­ly Ani­mat­ed with Chalk­board Illus­tra­tions

Watch A Brief His­to­ry of Time, Errol Mor­ris’ Film About the Life & Work of Stephen Hawk­ing

Stephen Hawking’s Uplift­ing Mes­sage: You Can Get Your­self Out of Any Hole, No Mat­ter What Their Size

The Largest Black Holes in the Uni­verse: A Visu­al Intro­duc­tion

Watch a Star Get Devoured by a Super­mas­sive Black Hole

Based in Seoul, Col­in Mar­shall writes and broad­casts on cities, lan­guage, and cul­ture. His projects include the book The State­less City: a Walk through 21st-Cen­tu­ry Los Ange­les and the video series The City in Cin­e­ma. Fol­low him on Twit­ter at @colinmarshall or on Face­book.