Hitching a Ride Out of a Gluttonous Black Hole

Feb 25, 2006 feature
Spinning Black Hole
Spinning Black Hole. Illustration: NASA/CXC/M.Weiss

“Ever since Stephen Hawking showed that black holes evaporate,” says Seth Lloyd, an MIT physicist, “people have wondered about the stuff that comes out of them. Is it just garbage, or is it something else?” With his piece published in Physical Review Letters on February 14, Lloyd attempts to show that quantum information does escape black holes, and that this information is useful and can have lasting impacts on how we understand our universe.

Lloyd’s assertion is that information escapes as black holes evaporate in what is known as a final state projection model. Final projection is nonlinear, but it is also considered self-consistent. “It’s funky,” Lloyd explains to Physorg.com, “but it is self-consistent. Anything that happens in a final state projection can ‘legally’ happen in a more conventional quantum mechanical manner.”

Final state projection is far from commonly accepted, however. One of the main problems some physicists have with these models is that in order the information has to travel at faster-than-light speeds to escape. While a final state projection model of black hole evaporation preserves unitarity and can even explain entropy as microstates of black hole horizon, getting past the idea of quantum information escaping at such high speeds is difficult. The idea of final state projection and escaping quantum information was put forth in the 1960s, but had been pretty much shunted aside by the 1980s. Despite attempts by a few physicists to substantiate the idea of faster-than-light quantum information escape from black holes, many remain skeptical.

Even Lloyd concedes that quantum bits moving faster than light hard to accept. “I admit that it’s strong medicine, things traveling faster than the speed of light.” But he insists his calculations show that it is possible. In a process similar to teleportation, quantum information inside the black hole entangles itself with Hawking radiation. As the black hole evaporates, the information is mostly preserved in the radiation. In Lloyd’s letter, his calculations show that the escaping quantum information has fidelity ≈ (8/3 π)2 . This means that if Lloyd is right, an average of half a bit of information is lost, no matter how many bits escape the black hole.

Lloyd’s calculations show that it is possible, in a final state projection scenario, for useful quantum information to escape a black hole. This of itself is a remarkable discovery, considering that it is commonly thought that nothing can escape a black hole, and that fairly useless Hawking radiation is the only product of black hole evaporation. Lloyd’s letter suggests that even the Hawking radiation has a use, as it will carry the entangled bits of quantum information.

But it is the implications regarding a theory of quantum gravity that Lloyd feels is especially significant. “We can understand quantum gravity by looking at how things process quantum information, and one of these things can be an evaporating black hole. This [letter] shows an example of applying methods of quantum information about quantum gravity and then getting something back.”

Not only does Lloyd believe that black holes can help physicists form a theory of quantum gravity, but he also thinks that final state projection shows how black holes can function as quantum computers. “It becomes a matter of putting information into a hole. The hole processes the information and spits it out through Hawking radiation.” Lloyd pauses, then continues: “We don’t know how to program a black hole, but maybe when we learn more about quantum gravity, we will be able to.”

Citation: Seth Lloyd. Almost Certain Escape from Black Holes in Final State Projection Models, Phys. Rev. Lett. 96, 061302 (2006)

By Miranda Marquit, Copyright 2006 PhysOrg.com

Explore further: Controlling core switching in Pac-man disks

add to favorites email to friend print save as pdf

Related Stories

An Interview with Thomas Vidick on quantum code cracking

Dec 15, 2014

Quantum computers, looked to as the next generation of computing technology, are expected to one day vastly outperform conventional computers. Using the laws of quantum mechanics—the physics that governs ...

Mathematicians prove the Umbral Moonshine Conjecture

Dec 15, 2014

Monstrous moonshine, a quirky pattern of the monster group in theoretical math, has a shadow - umbral moonshine. Mathematicians have now proved this insight, known as the Umbral Moonshine Conjecture, offering ...

Researcher shows that black holes do not exist

Sep 24, 2014

Black holes have long captured the public imagination and been the subject of popular culture, from Star Trek to Hollywood. They are the ultimate unknown – the blackest and most dense objects in the universe ...

The entropy of black holes

Sep 12, 2014

Yesterday I talked about black hole thermodynamics, specifically how you can write the laws of thermodynamics as laws about black holes. Central to the idea of thermodynamics is the property of entropy, which c ...

Recommended for you

Controlling core switching in Pac-man disks

Dec 24, 2014

Magnetic vortices in thin films can encode information in the perpendicular magnetization pointing up or down relative to the vortex core. These binary states could be useful for non-volatile data storage ...

World's most complex crystal simulated

Dec 24, 2014

The most complicated crystal structure ever produced in a computer simulation has been achieved by researchers at the University of Michigan. They say the findings help demonstrate how complexity can emerge ...

Atoms queue up for quantum computer networks

Dec 24, 2014

In order to develop future quantum computer networks, it is necessary to hold a known number of atoms and read them without them disappearing. To do this, researchers from the Niels Bohr Institute have developed ...

New video supports radiation dosimetry audits

Dec 23, 2014

The National Physical Laboratory (NPL), working with the National Radiotherapy Trials Quality Assurance Group, has produced a video guide to support physicists participating in radiation dosimetry audits.

Ultrasounds dance the 'moonwalk' in new metamaterial

Dec 23, 2014

Metamaterials have extraordinary properties when it comes to diverting and controlling waves, especially sound and light: for instance, they can make an object invisible, or increase the resolving power of ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.