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NIST Physicists Coax Six Atoms Into Quantum 'Cat' State
Science Daily | National Institute of Standards and Technology ^ | 2005-12-03

Posted on 12/03/2005 10:24:55 PM PST by sourcery

Scientists at the Commerce Department’s National Institute of Standards and Technology (NIST) have coaxed six atoms into spinning together in two opposite directions at the same time, a so-called Schrödinger “cat” state that obeys the unusual laws of quantum physics. The ambitious choreography could be useful in applications such as quantum computing and cryptography, as well as ultra-sensitive measurement techniques, all of which rely on exquisite control of nature’s smallest particles.

The experiment, which was unusually challenging even for scientists accustomed to crossing the boundary between the macroscopic and quantum worlds, is described in the Dec. 1 issue of Nature.* NIST scientists entangled six beryllium ions (charged atoms) so that their nuclei were collectively spinning clockwise and counterclockwise at the same time. Entanglement, which Albert Einstein called “spooky action at a distance,” occurs when the quantum properties of two or more particles are correlated. The NIST work, along with a paper by Austrian scientists published in the same issue of Nature, breaks new ground for entanglement of multiple particles in the laboratory. The previous record was five entangled photons, the smallest particles of light.

“It is very difficult to control six ions precisely for a long enough time to do an experiment like this,” says physicist Dietrich Leibfried, lead author of the NIST paper.

The ability to exist in two states at once is another peculiar property of quantum physics known as “superposition.” The NIST ions were placed in the most extreme superposition of spin states possible with six ions. All six nuclei are spinning in one direction and the opposite direction simultaneously or what physicists call Schrödinger cat states. The name was coined in a famous 1935 essay in which German physicist Erwin Schrödinger described an extreme theoretical case of being in two states simultaneously, namely a cat that is both dead and alive at the same time.

Schrödinger’s point was that cats are never observed in such states in the macroscopic “real world,” so there seems to be a boundary where the strange properties of quantum mechanics—the rule book for Nature’s smallest particles—give way to everyday experience. The NIST work, while a long way from full entanglement of a real cat’s roughly 1026 atoms, extends the domain where Schrödinger cat states can exist to at least six atoms. The Austrian team used a different approach to entangle more ions (eight) but in a less sensitive state.

In the NIST experiment, the ions are held a few micrometers apart in an electromagnetic trap. Ultraviolet lasers are used to cool the ions to near absolute zero and manipulate them in three steps. To create and maintain the cat states, the researchers fine-tuned trap conditions to reduce unwanted heating of the ions, improved cooling methods, and automated some of the calibrations and other formerly manual processes. One run of the experiment takes about 1 millisecond; the cat states last about 50 microseconds (about 1/20 as long). The team ran the experiment successfully tens of thousands of times, including numerous runs that entangled four, five, or six ions.

Entanglement and superpositions are being exploited in laboratories around the world in the development of new technologies such as quantum computers. If they can be built, quantum computers could solve certain problems in an exponentially shorter time than conventional computers of a similar size. For example, current supercomputers would require years to break today’s best encryption codes, (which are used to keep bank transactions and other important information secret) while quantum computers could quickly decipher the codes. Quantum computers also may be useful for optimizing complex systems such as airline schedules and database searching, developing "fraud-proof" digital signatures, or simulating complex biological systems for use in drug design.

Cat states, because they are superpositions of opposite overall properties that are relatively easy to verify, could be useful in a NIST-proposed design for fault-tolerant quantum computers. In addition, cat states are more sensitive to disturbance than other types of superpositions, a potentially useful feature in certain forms of quantum encryption, a new method for protecting information by making virtually all eavesdropping detectable.

The entangled cat states created by the NIST researchers also might be used to improve precision instruments, such as atomic clocks or interferometers that measure microscopic distances. Six ions entangled in a cat state are about 2½ times more sensitive to external magnetic fields than six unentangled ions, offering the possibility of better magnetic field sensors, or (for fixed external magnetic fields) better frequency sensors, which are components of atomic clocks. In addition, correlations between entangled ions could improve measurement precision, because a measurement of the spin of one of the entangled ions makes it possible to predict the spin of all remaining ions with certainty.

The research was funded by the Advanced Research and Development Activity/ National Security Agency, the Department of Defense Multidisciplinary University Research Initiative Program administered by the Office of Naval Research, and NIST.

More information about NIST research on quantum computing and cryptography, and spin-off applications in measurement science, is available at http://qubit.nist.gov.

As a non-regulatory agency of the Commerce Department’s Technology Administration, NIST promotes U.S. innovation and industrial competitiveness by advancing measurement science, standards and technology in ways that enhance economic security and improve our quality of life.


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KEYWORDS: nist; physics; science
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1 posted on 12/03/2005 10:24:57 PM PST by sourcery
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To: AntiGuv; Ernest_at_the_Beach; FairOpinion; phatoldphart; SunkenCiv

Ping


2 posted on 12/03/2005 10:25:19 PM PST by sourcery (Either the Constitution trumps stare decisis, or else the Constitution is a dead letter.)
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To: sourcery

BTTT


3 posted on 12/03/2005 10:30:36 PM PST by Fiddlstix (Tagline Repair Service. Let us fix those broken Taglines. Inquire within(Presented by TagLines R US))
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To: sourcery

4 posted on 12/03/2005 10:53:31 PM PST by orionblamblam ("You're the poster boy for what ID would turn out if it were taught in our schools." VadeRetro)
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To: Lady Jag; PetroniDE; Slings and Arrows
NIST Physicists Coax Six Atoms Into Quantum 'Cat' State

Really, really small kitty ping.

5 posted on 12/04/2005 12:04:04 AM PST by martin_fierro (< |:)~)
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To: sourcery

This article is full of mistakes.


6 posted on 12/04/2005 2:17:44 AM PST by wotan
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To: sourcery
a real cat’s roughly 1026 atoms

That's either a really small cat or some mighty big atoms.
7 posted on 12/04/2005 2:21:15 AM PST by GodBlessRonaldReagan (Count Petofi will not be denied!)
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To: wotan
This article is full of mistakes.

They completely misrepresent Schrödinger. Having two atoms spinning in opposite directions is not the same as a single cat being both dead and alive.

8 posted on 12/04/2005 2:37:54 AM PST by Monitor (Gun control isn't about guns; it's about control.)
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To: GodBlessRonaldReagan
He may have meant 10 to the 26th atoms or 10^26. Which is a wee bit larger than 1026 atoms.

Then again, after a second reading of the article he may have meant exactly what was written.

Public education at it's finest.
9 posted on 12/04/2005 2:53:16 AM PST by Dr.Zoidberg (Childrens classics updated for modern islam. "If You're Happy and You Know It, Go Kaboom!")
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To: Monitor
This article is full of mistakes.

They completely misrepresent Schrödinger. Having two atoms spinning in opposite directions is not the same as a single cat being both dead and alive.

You've not grasped the paradoxicality of the situation being described: each of the six ions is spinning both clockwise and counterclockwise simultaneously. So each ion is manifesting a superposition of classically incompatible states, which justifies the analogy to a cat being both alive and dead simultaneously.

10 posted on 12/04/2005 3:35:45 AM PST by snarks_when_bored
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To: snarks_when_bored
each of the six ions is spinning both clockwise and counterclockwise simultaneously

I wouldn't believe that even if I saw it--but if I saw it it couldn't be happening anyway. :-)

This stuff reminds me of the square root of -1--it shouldn't exist but it is a useful tool in the real world.
11 posted on 12/04/2005 3:44:36 AM PST by cgbg (MSM and Democratic treason--fifty years and counting...)
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To: sourcery
It's not that the cat IS both alive and dead, it's that we can't know which is true. We can only know the probability of the event being true. Only by actual observtaion is the actual state know and then it becomes one or the other.

from whatis.com:

Here's Schrödinger's (theoretical) experiment: We place a living cat into a steel chamber, along with a device containing a vial of hydrocyanic acid. There is, in the chamber, a very small amount of a radioactive substance. If even a single atom of the substance decays during the test period, a relay mechanism will trip a hammer, which will, in turn, break the vial and kill the cat. The observer cannot know whether or not an atom of the substance has decayed, and consequently, cannot know whether the vial has been broken, the hydrocyanic acid released, and the cat killed. Since we cannot know, the cat is both dead and alive according to quantum law, in a superposition of states. It is only when we break open the box and learn the condition of the cat that the superposition is lost, and the cat becomes one or the other (dead or alive). This situation is sometimes called quantum indeterminacy or the observer's paradox: the observation or measurement itself affects an outcome, so that it can never be known what the outcome would have been if it were not observed.

12 posted on 12/04/2005 3:46:40 AM PST by RobFromGa (Polls are for people who can't think for themselves.)
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To: cgbg
each of the six ions is spinning both clockwise and counterclockwise simultaneously

I wouldn't believe that even if I saw it--but if I saw it it couldn't be happening anyway. :-)

You're in good company: as (I think) Feynman said, nobody understands quantum mechanics...you just get used to it.

This stuff reminds me of the square root of -1--it shouldn't exist but it is a useful tool in the real world.

Imaginary numbers—which aren't imaginary at all, of course—play a crucial role in quantum mechanics. Here's a GIF image of the time-dependent one-dimensional Schrödinger equation, which describes how the wave function of a non-relativistic (i.e., slow-moving), undisturbed elementary particle such as an electron evolves over time:

Note the multiplication by i, the square root of -1.

13 posted on 12/04/2005 4:03:56 AM PST by snarks_when_bored
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To: Dr.Zoidberg

I know - did the author leave off the exponent or is he totally clueless?


14 posted on 12/04/2005 4:13:35 AM PST by GodBlessRonaldReagan (Count Petofi will not be denied!)
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The fog comes
on little cat feet.

It sits looking
over harbor and city
on silent haunches
and then moves on.

- Carl Sandburg


15 posted on 12/04/2005 7:07:39 AM PST by SunkenCiv (Down with Dhimmicrats! I last updated my FR profile on Wednesday, November 2, 2005.)
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To: RobFromGa
...it can never be known what the outcome would have been if it were not observed.

The old tree in the forest thingy. Science ain't so hard. :-)

16 posted on 12/04/2005 7:15:34 AM PST by Mind-numbed Robot (Not all that needs to be done needs to be done by the government.)
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To: snarks_when_bored

'Clockwise' and 'counterclockwise' is all dependent on point of view in that it depends on whether you are viewing the spinning ball from the top or the bottom of it's spinning axis.


17 posted on 12/04/2005 7:21:11 AM PST by Paul C. Jesup
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To: PatrickHenry
Quantum cat-states ping.
18 posted on 12/04/2005 7:31:31 AM PST by VadeRetro (Liberalism is a cancer on society. Creationism is a cancer on conservatism.)
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To: sourcery
"..........The ability to exist in two states at once is another peculiar property of quantum physics known as “superposition.”..........."

It always amazes me how beautiful and predictive the fruits of Western 'Scientific' inquiry are and in addition, how it all weaves together into a single unbroken tapestry as part of our civilization.

However, there are those that believe.............

1) There is no such thing as an atom.
2) The Earth is flat.
3) Evolution is false.

19 posted on 12/04/2005 7:43:12 AM PST by DoctorMichael (The Fourth-Estate is a Fifth-Column!!!!!!!!!!!!!!!)
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To: VadeRetro; Junior; longshadow; RadioAstronomer; Doctor Stochastic; js1138; Shryke; RightWhale; ...
SciencePing
An elite subset of the Evolution list.
See the list's explanation at my freeper homepage.
Then FReepmail to be added or dropped.

20 posted on 12/04/2005 8:11:54 AM PST by PatrickHenry (Virtual Ignore for trolls, lunatics, dotards, common scolds, & incurable ignoramuses.)
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To: sourcery
In addition, cat states are more sensitive to disturbance than other types of superpositions, a potentially useful feature in certain forms of quantum encryption, a new method for protecting information by making virtually all eavesdropping detectable.

This works in a cool way. You basically send your message via pulses of cat-state particles of which each is entangled with a particle you are NOT sending. If the cat-state of your stay-at-home particles collapses too soon, some eavesdropper has sensed your message along the way.

21 posted on 12/04/2005 8:26:44 AM PST by VadeRetro (Liberalism is a cancer on society. Creationism is a cancer on conservatism.)
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To: cgbg; longshadow
This stuff reminds me of the square root of -1--it shouldn't exist but it is a useful tool in the real world.

Why shouldn't it exist? I would imagine that it's as real as any other number. (Note the complex sentence.)

The real question (IMNSHO) is: "Why does the Sqrt(-1) suffice?" In other words, why do we not need CubeRoot(-1), etc.?

22 posted on 12/04/2005 8:34:10 AM PST by Doctor Stochastic (Vegetabilisch = chaotisch ist der Charakter der Modernen. - Friedrich Schlegel)
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To: sourcery; AntiGuv; RightWhale

I'm thinking that should be "10^26 atoms"
otherwise, interesting indeed.
I agree with Einstein: entanglement IS spooky.
I cannot help but wonder whether entanglement might lead to instantaneous communication over practically infinite distances.
corollary: if it can, then I cannot help but think that perhaps the SETI folks have been barking up a very wrong tree in listening for alien radio comsig.


23 posted on 12/04/2005 8:34:24 AM PST by King Prout (many accuse me of being overly literal... this would not be a problem if many were not under-precise)
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To: RobFromGa
It's not that the cat IS both alive and dead, it's that we can't know which is true. We can only know the probability of the event being true. Only by actual observtaion is the actual state know and then it becomes one or the other.

That's not correct. The two states are simultaneously "real" at the 50% level. Quantum superposition is a statement about reality, and not only about our knowledge of reality.

Einstein shared your misconception, and insisted that the two would be experimentally indistinguishable in any case. After his death, however, it was discovered that he was wrong: indeterminate states behave differently from merely undetermined states. The latter will obey Bell's Inequality when you compare correlated measurements; the former will violate it.

The experimental fact is that entangled states yield measurements that violate Bell's Inequality.

24 posted on 12/04/2005 9:03:57 AM PST by Physicist
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To: King Prout

Doesn't work that way. You can't send information faster than light.


25 posted on 12/04/2005 9:04:08 AM PST by js1138 (Great is the power of steady misrepresentation.)
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To: All
Regarding the 1026 issue:

Here is the original press release. You can see that the "26" is superscripted. The "1026" was a copy-and-paste job from the original, nothing more.

26 posted on 12/04/2005 9:06:47 AM PST by Physicist
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To: js1138

are you sure?
last I checked - the US/German experiment - the implication was instantaneous mirroring of changes irrespective of distance.


27 posted on 12/04/2005 9:07:12 AM PST by King Prout (many accuse me of being overly literal... this would not be a problem if many were not under-precise)
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To: King Prout

I'm just mirroring what I've read. The technique sounds impressive when written about, but I'm pretty sure it doesn't allow communication faster than light.


28 posted on 12/04/2005 9:11:28 AM PST by js1138 (Great is the power of steady misrepresentation.)
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To: js1138

I'll be the first to admit I'm not even at piker-comprehension concerning QM, so all of this is like nifty sorcerous lunacy to me.


29 posted on 12/04/2005 9:17:59 AM PST by King Prout (many accuse me of being overly literal... this would not be a problem if many were not under-precise)
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To: sourcery
The name was coined in a famous 1935 essay in which German physicist Erwin Schrödinger described an extreme theoretical case of being in two states simultaneously, namely a cat that is both dead and alive at the same time.

Schrödinger obviously never drank tequila or he would know an entire human body can enter a cat state on any given morning.

So9

30 posted on 12/04/2005 9:20:49 AM PST by Servant of the 9 (Trust Me)
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To: js1138
Doesn't work that way. You can't send information faster than light.

Not in classical or relativistic physics you can't, but there are some questions in quantum physics.
Electrons do not move from one orbit to another of an atom, but disapear one place and appear instantaneously in another orbit. There are a nuumber of other quantum transitions that take place without passage of time.
Is information moved? That is the difficult quible.

So9

31 posted on 12/04/2005 9:27:37 AM PST by Servant of the 9 (Trust Me)
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To: Doctor Stochastic; snarks_when_bored
The real question (IMNSHO) is: "Why does the Sqrt(-1) suffice?" In other words, why do we not need CubeRoot(-1), etc.?

Point of Information: do you mean "why do we NOT need CubeRoot (-1), etc." in order to model QM, or are you asking the question in a more abstract, purely mathematical sense?

32 posted on 12/04/2005 9:32:16 AM PST by longshadow
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To: Servant of the 9

Everything I have read about quantum entanglement suggests it cannot be the basis of faster than light communication.

At the very least it requires you to physically transport the entangled particles to the receiving destination. That pretty much rules out using it to meet alien civilizations.


33 posted on 12/04/2005 9:35:42 AM PST by js1138 (Great is the power of steady misrepresentation.)
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To: King Prout

Time is an illusion. So is space. So is causality. As soon as we perceive the universe correctly, distance will be annihilated, as will past and future.


34 posted on 12/04/2005 9:40:08 AM PST by RightWhale (Not transferable -- Good only for this trip)
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To: js1138
Everything I have read about quantum entanglement suggests it cannot be the basis of faster than light communication.
At the very least it requires you to physically transport the entangled particles to the receiving destination. That pretty much rules out using it to meet alien civilizations.

Perhaps not interstellar communications, but instantaneous communication across the diameter of an atom has profound implications for the ultimate speed of electronics devices of all types.

So9

35 posted on 12/04/2005 9:42:43 AM PST by Servant of the 9 (Trust Me)
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To: Servant of the 9; js1138; RightWhale; Physicist

from what little I have comprehended of what little I have read on the subject, the following is the (quite possibly incorrect impression of) property of entanglement which interests me:

2 entangled particles, separated by significant distance.
perturb one of the particles, and the other particle instantly undergoes the same perturbation.

if this is so, one can consider one state of perturbation a zero, and another state a one, thus creating a binary communicator allowing instantaneous -if absurdly simple- data transfer irrespective of distance.

again assuming all the above, and assuming the number of entangled particles can be jacked up to something more useful, then REAL instant datacomm is possible. the applications would of course include controlling long-range unmanned recon on Earth and (more importantly) in space... no more long waiting periods between command, execution, and reply - it'd become similar to actually being there in real-time, more like controlling an RC car on your lawn.

That'd be damn nifty... if it is indeed possible


36 posted on 12/04/2005 9:46:48 AM PST by King Prout (many accuse me of being overly literal... this would not be a problem if many were not under-precise)
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To: RightWhale

well, philosophically I can see how that could be true - only problem: we are PART of the illusion, so to transcend the illusion we would have to completely transcend ourselves.

that can wait till I die, I reckon :)


37 posted on 12/04/2005 9:49:01 AM PST by King Prout (many accuse me of being overly literal... this would not be a problem if many were not under-precise)
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To: longshadow; Doctor Stochastic; snarks_when_bored

um, isn't the cube root of "negative one" simply "negative one"?

I mean, -1^3 = -1...


38 posted on 12/04/2005 9:50:51 AM PST by King Prout (many accuse me of being overly literal... this would not be a problem if many were not under-precise)
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To: King Prout
Yeah, but information cannot be communicated this way. So near and yet so far. BTW, entropy as it is called in information theory is not the same thing as entropy in thermodynamics, just something with the same mathematical form--there is some confusion about this on FR. They are two different words that happen to be spelled and pronounced the same.
39 posted on 12/04/2005 9:53:27 AM PST by RightWhale (Not transferable -- Good only for this trip)
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To: King Prout

Not at all. We create the illusion. There is nothing in nature that requires the illusion. Just as there are no patterns in nature: we create the patterns. That appears to be our job.


40 posted on 12/04/2005 9:56:22 AM PST by RightWhale (Not transferable -- Good only for this trip)
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To: js1138

...and, to have radio communications with the civilized world when in the heart of an equatorial jungle, one must physically transport a radio to the remote location.

still beats humping back and forth with handwritten notes, no?

a total suppostition - what if there is a specific kind or range of entanglements which are simply easier or more durable or more useful than the others? what if there is what amounts to a "universal frequency" for entangled communication?

I cannot even begin to have serious thoughts on the matter, lacking anything close to even a beginner's knowledge on it, but it makes for pleasant fantasy.


41 posted on 12/04/2005 9:56:39 AM PST by King Prout (many accuse me of being overly literal... this would not be a problem if many were not under-precise)
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To: snarks_when_bored
You're in good company: as (I think) Feynman said, nobody understands quantum mechanics...you just get used to it.

I am much more used to the idea since I began wearing the official Schrödinger's Cat T-shirt. If I spin on axis real fast in front of a mirror, I can read both front and back simultaneously.

http://www.thinkgeek.com/tshirts/science/6dff/

42 posted on 12/04/2005 9:56:40 AM PST by rootkidslim (... got the Sony rootkit on your Wintel box? You can thank Orrin Hatch!)
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To: longshadow

Purely mathematical and somewhat philosophical. It's an interesting question. Why is i sufficient? (Run your spell&grammar-checker on this.)


43 posted on 12/04/2005 9:57:28 AM PST by Doctor Stochastic (Vegetabilisch = chaotisch ist der Charakter der Modernen. - Friedrich Schlegel)
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To: King Prout
...and, to have radio communications with the civilized world when in the heart of an equatorial jungle, one must physically transport a radio to the remote location.

Not true. Think about it.

44 posted on 12/04/2005 9:58:00 AM PST by js1138 (Great is the power of steady misrepresentation.)
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To: RightWhale

hrmn... no patterns in nature...
can't agree - we observe and describe patterns, but they were extant before we did so.


45 posted on 12/04/2005 9:58:04 AM PST by King Prout (many accuse me of being overly literal... this would not be a problem if many were not under-precise)
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To: js1138

well, if you had the right materials, you might be able to construct a radio locally.


46 posted on 12/04/2005 9:59:12 AM PST by King Prout (many accuse me of being overly literal... this would not be a problem if many were not under-precise)
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To: RightWhale

why can data NOT be transmitted in this manner?


47 posted on 12/04/2005 10:00:34 AM PST by King Prout (many accuse me of being overly literal... this would not be a problem if many were not under-precise)
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To: King Prout

There are two others. There are always three cube roots. You might have fun finding them.


48 posted on 12/04/2005 10:00:43 AM PST by Doctor Stochastic (Vegetabilisch = chaotisch ist der Charakter der Modernen. - Friedrich Schlegel)
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To: King Prout; Doctor Stochastic; snarks_when_bored
I mean, -1^3 = -1...

Yup. If the number of roots is odd, it doesn't generate anything "interesting" that would provide a basis for an orthogonal direction, as "i" does in the case when you take the SqrRoot(-1). "i" is used to define an orthogonal dimension wrt to the real number line, together forming the basis of the Complex Plane.

49 posted on 12/04/2005 10:02:03 AM PST by longshadow
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To: Physicist
I was under the assumption that the likelihood of the "dead" state would be dalculated according to a function which started with a value of 0 at time 0, and apporaches 1 at time infinity. The speed of the approach to one is determined by the characteristics of the actual material. But, this is a probablility and is not the same as actual reality which can only be determined by observation.
50 posted on 12/04/2005 10:02:46 AM PST by RobFromGa (Polls are for people who can't think for themselves.)
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