ScAm

4 Scientific American, April 2020

LETTERS

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BLACK HOLE BREAKOUT
In “Escape from a Black Hole,” Steven  B.
Giddings gives us a fascinating update on
developments in the black hole informa-
tion crisis, the seeming paradox of quan-
tum rules and general relativity indicat-
ing that black holes destroy information
despite quantum mechanics saying that
information cannot be destroyed.
One thing puzzles me about his ac-
count. He explains that the three leading
candidate solutions to the crisis all have
the same thorny problem: they violate the
principle of locality, which maintains that
no influence can move across space faster
than the speed of light. But I’ve read else-
where that the violation of locality has
already been rigorously established from
both observations and theoretical analy-
ses of quantum entanglement. If that as-
sessment is correct, why is such violation
still regarded as a problem for black hole
theories? And why doesn’t Giddings men-
tion the confirmation of nonlocality in en-
tanglement studies as helping things
along for these theories?
Bruce Ecker New York City

GIDDINGS REPLIES: Ecker’s question re­
flects a common misunderstand ing of the
precise meaning of locality in physics. It
is true that quantum mechanics has prop­
erties—specifically, entanglement—that ap ­
pear to represent a kind of nonlocality.
This observation famously bothered Al­

bert Einstein, who referred to its conse­

quences as “spooky action at a distance.”

But quantum field theory fully reconciles

locality with quantum mechanics. Al­

though it exhibits entanglement, the pre­

cise statement of locality is that there is no

way to send a signal (meaning no way to

transmit information) nonlocally—that is,

faster than the speed of light. Mere quan­

tum entanglement does not allow such sig­

naling. It is this locality property of quan­

tum field theory that directly conflicts

with the statement that, apparently, infor­

mation must escape a black hole and that

prompts us to consider modifications of

quantum field theory.

CONSCIOUS DISTINCTION

Christof Koch gives an interesting summa-

ry of theories of human consciousness and

whether computers can attain it in “Proust

among the Machines.” The popular me-

dia—including Koch, it would seem—as-

sume that computer consciousness would

be much like our own, with a desire to be

free, safe and alive. But computers are so

physically different from ourselves and

their reason for existing so different that if

they were to gain consciousness, it would

be very distinct from what we experience.

Take self-driving cars, for example.

Their programming, or training, is a kind

of evolutionary process where the best-

performing connections win out. If cars

being conscious would result in better

driving, then, sooner or later, it would hap-

pen. The only thing such a car would

“want,” however, would be to stay on the

road and not hit anything. Behavior such

as admiring the scenery would not con-

tribute to good driving and would be elimi-

nated in the training. What would it be like

to “be” such a car? The experience would

be so distant from our own that we would

probably not recognize it as consciousness.

I expect that when truly intelligent com-

puters arrive, we will be surrounded by ar-

tificial consciousness and not even realize

it. Or maybe we already  are.

Paul Colbourne Ottawa

PLASTICS AND CLIMATE

In “Learning to Love Plastic” [Ventures],

Wade Roush asserts that standard plastic

is good for the environment because it

traps carbon that would contribute to cli-

mate change and that we should thus not

adopt biodegradable plastic to reduce

waste. His argument is flawed in two ways.

The first is a misunderstanding of the

problem, which he identifies as the carbon

intensity of biodegrading plastics. The re-

lease of carbon dioxide is a natural part of

biodegradation, yet Roush implies this is a

problem unique to biodegradable plastics.

Fallen leaves on the forest floor do the

same. If anything, the problem with bio-

degradable plastics is that they’re weaker

than those derived from petrochemicals,

and in the same issue of Scientific Ameri­

can, “Bioplastics for a Circular Economy,”

by Javier Garcia Martinez, highlights ef-

forts to strengthen biodegradable plastics

as one of the “Top 10 Emerging Technolo-

gies of  2019.”

The second flaw in Roush’s position is

more important: he fails to recognize that

we can tackle two problems at once. Biode-

gradable plastics are a hopeful solution to

a serious problem: plastic pollution. They

are not the root cause of a different but

certainly more serious problem: climate

change because of anthropogenic carbon

emissions. Thankfully, we are developing

other solutions to solve that problem that

don’t involve treating petrochemical plas-

tics as carbon sinks.

Zachary Epstein Houston, Tex.

I was appalled to see the following state-

ment in Roush’s article with no support-

ing documentation: “And your sup posedly

eco-conscious cloth grocery bag is more

damaging to the environment than con-

ventional plastic bags—unless you reuse it

literally thousands of times.” This “idea”

defies logic and demands evidential sup-

port. A reusable, plant-based cotton bag

December 2019

“I expect that when

truly intelligent

computers arrive,

we will be surrounded

by artificial conscious -

ness and not even

realize it.”

paul colbourne ot tawa

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