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FROM VIDEO GAMES TO RISC-V ISA

“I got into
computers
through video
games, like
Space
Invaders,” says
Krste Asanović,
California, Berkeley (UC
Berkeley). “I taught myself
to program mainly to
write games.”
Asanović earned his
bachelor’s degree in electrical
and information sciences from
the University of Cambridge in
the U. K., and received his Ph.D.
in computer science from UC
Berkeley.

While his main areas of focus are computer architecture, VLSI design, parallel programming, and operating system design and security, Asanović’s recent focus has been on the RISC-V Foundation.

RISC-V is a free and open Instruction Set Architecture (ISA) serving as the interface between hardware and software.

“The RISC-V ISA started at Berkeley,” explains Asanović.

“It is meant to replace Intel
and ARM ISAs. It has lots of
worldwide interest now.”
The dominant industry ISAs
are proprietary, Asanović says.

Servers, desktop, and laptop computers are mostly built around Intel’s x86 ISA, while mobile devices are built on ARM ISAs.

The point of RISC-V,
Asanović says, “is to let anyone
build their own processor and
take advantage of its inherent
design flexibility.”
In terms of where computer
architecture research is headed,
Asanović thinks the exciting
areas to explore are artificial
intelligence (AI) and security.

He feels new AI applications are creating incredible demand, while in security the situation is bad and getting worse.

“One of the challenges will be to create a truly secure computing environment,” Asanović says.

— John Delaney

vealed the surprising quantum error-correcting codes referred to at the start of the article, in which the surface information captures a subtle redundancy in the way information is encoded in the higher-dimen-sional bulk.

 

A Cosmic Firewall?

Hawking’s concession did not end
the controversies about black holes,
because of ambiguity when one par-
ticle of an entangled pair falls in. Tra-
ditionally, this particle would remain
entangled with its partner outside,
sharing its quantum information. If
this information is also carried away
in the Hawking radiation, however,
that violates a quantum rule known as
“monogamy of entanglement.”
For many years, physicists thought
this conflict might be tolerable be-
cause no one could ever compare the
information inside and outside, but
in 2012 a group of physicists showed
that this loophole fails right at the
horizon. Instead, they proposed that
passing through the horizon destroys
the entanglement, creating a huge
sheet of energy at the horizon known
as the “firewall.” This idea is repel-
lent to many physicists, because a
guiding principle for Einstein was
that falling freely through space
feels the same everywhere, with “no
drama” at the event horizon. Other
researchers have proposed other
ideas, for example that the informa-
tion carried in is conveyed to a differ-
ent part of space by a “wormhole” and
thus survives the evaporation.

These radical ideas, driven by the information paradox, threaten to restructure fundamental aspects of how physicists understand the universe. Although there remains no consensus on the resolution, Carroll said, it has “ settled into something that many people agree is a problem.”

 

Emergent Spacetime

As if wormholes were not exotic
enough, Carroll, Swingle, and other
physicists are exploring the idea that
the entire structure of spacetime
emerges from entangled quantum in-
formation. This alternative approach,
sometimes called “It from Qubit,”
starts with abstract points, with no
sense of space between them at all,
said Swingle. “Then you start entan-
gling them in some characteristic
pattern, and that pattern can take on
a geometric structure, in that you fol-
low a link from one particle to anoth-
er particle, eventually you have some
sense of being able to go somewhere,
some sense of distance, some sense
of space.”

This ambitious scheme remains a work in progress and may not prove successful, but there is no doubt that information will continue to guide fundamental thinking about physics. “Taking an information-theoretic point of view,” Swingle said, can provide a “unifying framework to think about lots of different things. It’s sort of a software versus a hardware view of the world.”

 

Further Reading

Moskowitz, C.

Tangled Up in Spacetime, Scientific American, Oct. 26, 2016 http://bit.ly/2K5Oj87

Wood, C.

Black Hole Firewalls Could Be Too Tepid to Burn, Quanta Magazine, Aug. 22, 2018 http://bit.ly/2SzYaH3

It from Qubit: Simons Collaboration on Quantum Fields, Gravity and Information, Simons Foundation, http://bit.ly/32Qyl Y7

Don Monroe is a science and technology writer based in Boston, MA, USA.

© 2019 ACM 0001-0782/19/11 $15.00
Carroll, Swingle,
and other
physicists
are exploring
the idea that
the entire structure
of spacetime
emerges from
entangled quantum
information.