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Quantum Computing: A view from the enemy camp
SIGFPE writes "There seems to be an unthinking acceptance by many people that quantum computers are now on their unstoppable way up and before too long we'll be cracking RSA and simulating protein folding on complex quantum computers. However there is another point of view that considers quantum computers to be as difficult to make as perpetual motion machines - and for much the same reason: entropy. As an antidote to all the successes that have been reported on /. here is a just published and highly readable preprint by a sceptical mathematical physicist."
LOS ANGELES -- The FBI has alerted law-enforcement agencies in eight Western states that it has unconfirmed information terrorists may be targeting suspension bridges on the West Coast.
... on the bridge to assure that everyone who is on the bridge belongs on the bridge."
The Justice Department confirmed the warning Thursday after California Gov. Gray Davis said that law-enforcement officials had "credible evidence" that four California bridges, including the Golden Gate, may be the target of an attack.
The FBI said in its alert that authorities had not yet corroborated the information but decided to issue a warning.
Six "incidents" were planned during rush hour between today and Nov. 7, the agency said.
"Reportedly, unspecified groups are targeting suspension bridges on the West Coast," the FBI said in the message.
The warning was sent Wednesday to law-enforcement agencies in California, Washington, Oregon, Arizona, Nevada, Utah, Montana and Idaho.
Justice Department spokeswoman Mindy Tucker said the information that prompted the warning was "at a lower level" than what led to the FBI's general warning to Americans on Monday. "We are working to verify the validity" of the information, Tucker said.
A senior U.S. official, speaking on condition of anonymity, said the threat is based on new information acquired by U.S. intelligence and law enforcement since Monday's warning. The official said a foreign Islamic terrorist group may be targeting the bridges.
Davis mentioned the warning Thursday during a news conference in which he also appointed the state's new terrorism security czar, George Vinson, a 23-year veteran of the FBI.
"The best preparation is to let terrorists know, we know what you're up to, we're ready for you," Davis said.
Homeland Security Director Tom Ridge said Thursday that even though federal authorities had not publicly released the information, he would not second-guess Davis' decision to do so.
"I respect the decision Governor Davis made; he exercised his judgment," Ridge said. Federal authorities "thought it was important enough to relate to the governor, and the governor thought it was important enough to relate to his citizens," Ridge said.
In response to the warning, Oregon Gov. John Kitzhaber ordered stepped-up police patrols of the state's most heavily traveled bridges. But he said the patrols were only as a precaution, and said there was no reason for motorists to avoid the bridges.
"One of the objectives of terrorism is to terrorize people," he said. "It would be an unfortunate victory we would hand them if people simply stopped driving."
The California bridges that Davis identified as possible targets were San Francisco's Golden Gate and Bay Bridges, the Vincent Thomas Bridge at the Port of Los Angeles and the Coronado Bridge in San Diego.
Security around the bridges has been heightened and involves the National Guard, U.S. Coast Guard and California Highway Patrol, he said.
The Golden Gate -- a 4,200-foot-long suspension bridge -- spans the Golden Gate Strait at the entrance to San Francisco Bay. About 110,000 vehicles use the bridge per day. The 4 1/2-mile long San Francisco-Oakland Bay Bridge is used by about 270,000 vehicles daily -- the highest use of any bridge in the nation.
"We feel we're well-prepared for any nefarious and criminal actions," said Jeff Weiss, spokesman for the San Francisco-Oakland Bay Bridge. "We're routinely inspecting the IDs of workers
Although authorities have registered hundreds of bomb threats toward sites in California, this is only the second threat judged to be credible since the Sept. 11 attacks, Davis said. The first targeted Los Angeles movie studios.
Several Hollywood studios stopped giving tours and increased armed patrols after a general warning Sept. 20 from the FBI that television and movie facilities could be targets of terrorist attacks
While everything stated in this paper is all well and good and valid, he's missing the fundamental point of innovation.
You make no progress with pessimism.
CyberBlood
If it is possible for quantum computers to look sideways into parallel universes to perform their calculations and evolution dictates that any lifeform that does not take full advantage of its enviroment will not survive to procreate then humans must have a latent ability to percieve parallel worlds too.
If it is possible to utilize parallel processing then life would have had to evolve the ability to take advantage of that.
Since we don't all have ESP then quantum computers are bullshit.
And no, we don't want to hear about the dog in the UK that knows when its owner has made the decision to come home.
If voting were effective, it would be illegal by now.
An interesting article, but it seems to rely on several strange arguments. I wouldn't agree that the accuracies required in manufacture and operation are not achieveable. It would seem to me that a fabrication accuracy of 1 part in 10^5 is scarcely unachieveable, especially since we have everyday devices, for example LCD monitors in which less than 1 pixel in 1 million is dead, and those are consumer products.
I don't necessarily buy his argument about the inherent fault-intolerence of quantum computing either, since it relies on the idea that a simple computer with no fault tolerence built in is fault intolerant! Scarcely a surprise. He didn't make a convincing argument that building in fault tolerance is impossible, only that it isn't being done in the simple designs he notes. Maybe I've misunderstood, but it would seem that this is an avenue for more research, rather than less.
It seems to me that in the end the whole of his argument relies on the engineering argument that we don't at present have any way to measure large numbers of single spin states (or indeed any single spin state). This would seem again to be an argument for more research, rather than less, since engineering serendipity is not a predictable mathematical process.
I understand his frustration that quantum computing is taking a lot of research funding from other areas, but I'd be a little more cautious than he is about saying that it definitely _can't_ work.
Ummm....
While this sentence is taken out of context, it is still completely wrong. We use parallel processing all the time. The parallel computation part of quantum computing seems to work in both theory and in the lab as well.
The argument against QC is really much simpler than Perdo's convoluted logic requires. Dyakonov says that the problem isn't that a quantum computer couldn't do the calculations fast. The problem is that it would take nearly forever to build the computer in the first place.-John Van Voorhis
To a Lisp hacker, XML is S-expressions in drag.
Even if it were proven conclusively that "souls", and all the other things that religions talk about, did not exist, I don't believe that would destroy religion. If the concepts are complex enough, as they almost have to be, that the non-specialist could never understand the proof, then the majority of people would have a simple choice: believe the scientists, who say that they're just machines, or believe the priests, who say that they're more than machines.
In other words, the situation would be just like it is now (Dawkins anyone?), except that the scientists would have a sacred book of their own.
Don't you just love it when people write inflammatory scientific papers about how quantum computing is impossible with today's technology and then pop onto the forum to defend it... Truely sad.
i know there is some concern about the power requirements of quantum computers, but my physicist friends assure me that cold fusion reactors will provide all the power they need.
nobody
parturiunt montes, nascetur ridiculus mus
As sung by the infamous Mc Hawking.
Entropy, how can I explain it? I'll take it frame by frame it,
to have you all jumping, shouting saying it.
Let's just say that it's a measure of disorder,
in a system that is closed, like with a border.
It's sorta, like a, well a measurement of randomness,
proposed in 1850 by a German, but wait I digress.
"What the fuck is entropy?", I here the people still exclaiming,
it seems I gotta start the explaining.
You ever drop an egg and on the floor you see it break?
You go and get a mop so you can clean up your mistake.
But did you ever stop to ponder why we know it's true,
if you drop a broken egg you will not get an egg that's new.
That's entropy or E-N-T-R-O to the P to the Y,
the reason why the sun will one day all burn out and die.
Order from disorder is a scientific rarity,
allow me to explain it with a little bit more clarity.
Did I say rarity? I meant impossibility,
at least in a closed system there will always be more entropy.
That's entropy and I hope that you're all down with it,
if you are here's your membership.
You down with entropy?
Yeah, you know me!
You down with entropy?
Yeah, you know me!
You down with entropy?
Yeah, you know me!
Who's down with entropy?
Every last homey!
Defining entropy as disorder's not complete,
'cause disorder as a definition doesn't cover heat.
So my first definition I would now like to withdraw,
and offer one that fits thermodynamics second law.
First we need to understand that entropy is energy,
energy that can't be used to state it more specifically.
In a closed system entropy always goes up,
that's the second law, now you know what's up.
You can't win, you can't break even, you can't leave the game,
'cause entropy will take it all 'though it seems a shame.
The second law, as we now know, is quite clear to state,
that entropy must increase and not dissipate.
Creationists always try to use the second law,
to disprove evolution, but their theory has a flaw.
The second law is quite precise about where it applies,
only in a closed system must the entropy count rise.
The earth's not a closed system' it's powered by the sun,
so fuck the damn creationists, Doomsday get my gun!
That, in a nutshell, is what entropy's about,
you're now down with a discount.
You down with entropy?
Yeah, you know me!
You down with entropy?
Yeah, you know me!
You down with entropy?
Yeah, you know me!
Who's down with entropy?
Every last homey!
How we know is more important than what we know.
I previewed this comment before I posted, and it was fine. I must have nicked one of the tags just before I hit "Submit". Very sorry.