Search found 477 matches

by ATCG
Sun Sep 23, 2018 3:57 pm UTC
Forum: Science
Topic: Wave Function Collapse and information
Replies: 3
Views: 2735

Re: Wave Function Collapse and information

So my question is: Is it possible for the left observer to know (over a large number of measurements), if the photon they are looking at has already decohered before their measurement? (ie. did the right side observer already measure it?) Short answer: No Relevant cartoon (note the mouse-over text)...
by ATCG
Sat Mar 31, 2018 7:23 am UTC
Forum: Mathematics
Topic: Proving One of Demorgan's Law
Replies: 5
Views: 4613

Re: Proving One of Demorgan's Law

It looks like you are writing a natural deduction proof (ala Gentzen.)[/Clippy] If so, you are on the right track. ...why are you assuming (-P v -Q)? @j_s, take Cauchy's question seriously. In fact, turn it into two questions: ⋅ How do you intend to discharge this assumption? Hint: What wi...
by ATCG
Mon Mar 07, 2016 5:33 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 1652 "Conditionals"
Replies: 77
Views: 13343

Re: 1652 "Conditionals"

"But where will you be if I don't want to hang out?"

Disney cats reply.
by ATCG
Tue Jan 29, 2013 9:55 am UTC
Forum: Science
Topic: Quantum Biology
Replies: 13
Views: 4884

Re: Quantum Biology

"Seth Lloyd on Quantum Life" covers, from the perspective of a quantum-computing researcher, much the same ground as the BBC article (particularly the role of QM in the photosynthesis of green and purple sulfur bacteria) and addresses a number of the issues raised above (e.g. the maintena...
by ATCG
Wed Aug 03, 2011 2:37 pm UTC
Forum: News & Articles
Topic: It's official, Hollywood is fucking with us
Replies: 120
Views: 19262

Re: It's official, Hollywood is fucking with us

As noted by jakovasaur, Battleship isn't the only Hasbro-board-game-inspired movie in the works. While waiting to see when (and if) Monopoly makes it to the big screen, we can enjoy the faux trailer for a film that might have been made by Oliver Stone (and hope the real thing is as good).
by ATCG
Sun Jul 17, 2011 12:49 am UTC
Forum: Science
Topic: Is Godel's Incompleteness actually relavent to physics?
Replies: 14
Views: 2355

Re: Is Godel's Incompleteness actually relavent to physics?

Does GIT apply to the theoretical Theory of Everything, and if so, how? A good discussion of this can be found in Torkel Franzén's Gödel's Theorem: An Incomplete Guide to Its Use and Abuse , section 4.4 "Incompleteness and the TOE". No less distinguished physicists than Freeman Dyson (in ...
by ATCG
Sun Jun 12, 2011 8:02 pm UTC
Forum: Mathematics
Topic: PhD in hand
Replies: 43
Views: 6111

Re: PhD in hand

Congratulations on achieving a major milestone. It sounds like you are well on your way to further accomplishments.
by ATCG
Thu May 12, 2011 3:58 pm UTC
Forum: Science
Topic: Brain entanglement - credible?
Replies: 61
Views: 7839

Re: Brain entanglement - credible?

I know I have heard about enzymes or something possibly using quantum tunneling for catalysis (but sadly I can't remember where) . . . You may be thinking of the discovery that bacteria exploit QM to boost the efficiency of photosynthesis . (The fact that bacteria have "discovered" the ad...
by ATCG
Tue Apr 26, 2011 2:47 am UTC
Forum: Science
Topic: Bio question
Replies: 22
Views: 2499

Re: Bio question

Do you include non-infectious diseases among "all diseases"?
by ATCG
Sun Apr 24, 2011 1:53 am UTC
Forum: Mathematics
Topic: Maths problems to do over spring break
Replies: 7
Views: 1475

Re: Maths problems to do over spring break

Find all solutions to the equation 3 * x * 7 = y . Give your answers in the form (x, y) . I read this as asking for an explicit list of x, y pairs that satisfy the given equation - something that resembles (picking values out of the air for purposes of illustration): (1,3), (1,5), (3,5) I s...
by ATCG
Fri Apr 15, 2011 11:40 pm UTC
Forum: Computer Science
Topic: Ultra-parallel computer
Replies: 12
Views: 2679

Re: Ultra-parallel computer

Sounds just a bit like the transputer. See also systolic arrays.
by ATCG
Wed Apr 06, 2011 3:21 pm UTC
Forum: Mathematics
Topic: Theorem being undecidable question
Replies: 8
Views: 1261

Re: Theorem being undecidable question

So, on to my question....are the statements "X is formally undecidable in consistant system Y" and "Y+X and Y-X are consistant systems" equivalent? . . . Intuitively it seems to me that these statements should be the same....I mean, if something is undecidable in a consistant sy...
by ATCG
Tue Apr 05, 2011 12:26 am UTC
Forum: Mathematics
Topic: Expected trials for “winning streak” of given length
Replies: 11
Views: 2311

Re: Expected trials for “winning streak” of given length

This makes sense, thank you. You're welcome. Unfortunately my schedule makes for long delays between forum visits. I’m still looking for the distribution over the positive integers giving the likelihood that the nth trial will complete the first streak of k successes. (Or similarly, the likelihood ...
by ATCG
Sun Apr 03, 2011 8:14 pm UTC
Forum: Mathematics
Topic: Expected trials for “winning streak” of given length
Replies: 11
Views: 2311

Re: Expected trials for “winning streak” of given length

An absorbing Markov chain works well here: transitions.PNG After i consecutive successful trials, the process can be found in state S_i , i \leq n . If we count the number of times N_i that each state S_i is expected to be visited (as the number of trials grows without bound), we find that N_{i+1} =...
by ATCG
Sun Mar 20, 2011 5:59 am UTC
Forum: Science
Topic: public misconceptions
Replies: 1073
Views: 149983

Re: public misconceptions

Fluorescent bulbs may be taking the blame due one of their relatives. Intense short-wave UV radiation emitted by damaged metal halide and mercury vapor bulbs is capable of inflicting severe skin and eye burns. Injuries from these bulbs have occurred most frequently in school gymnasiums.
by ATCG
Wed Feb 16, 2011 9:07 am UTC
Forum: Science
Topic: GPS Error
Replies: 7
Views: 1443

Re: GPS Error

My receiver gives an error value in feet of how strong the signal is, and I wonder if any of you think this is acceptable to use as my uncertainty for the final 'y' position. I suspect your GPS receiver is actually estimating error based on dilution of precision - a figure of merit that depends on ...
by ATCG
Sat Feb 12, 2011 8:45 pm UTC
Forum: News & Articles
Topic: Dark Matter Lives!
Replies: 17
Views: 1993

Re: Dark Matter Lives!

Somewhat funny that the letter's author referred to his idea as a "modest proposal". It's a reference to another bit of satire : Okay, that last paragraph kinda gives the game away -- that and the use of the phrase "modest proposal", a reference to the 18th century satirist Jona...
by ATCG
Sat Feb 12, 2011 6:54 pm UTC
Forum: News & Articles
Topic: Dark Matter Lives!
Replies: 17
Views: 1993

Poe's Law Lives!

Uh, before losing too much sleep over this . . . [Lloyd] originally sent the letter as an email to [Dennis] Overbye [the author of the original NYT article on dark energy], who found it amusing and suggested Lloyd submit it as a letter to the editor. And it was accepted: "Apparently the editor ...
by ATCG
Wed Jan 26, 2011 5:27 am UTC
Forum: Mathematics
Topic: ridiculous naming trend in definitions
Replies: 18
Views: 3127

Re: ridiculous naming trend in definitions

mike-l wrote:
Bjorgen Jansen wrote:I also remember there being a theorem called the hairy balls theorem

The Hairy Ball Theorem is an important fixed point result!

This hasn't stopped naughty undergraduates from adopting a very rude alternative name for it.
by ATCG
Wed Dec 22, 2010 4:58 pm UTC
Forum: Science
Topic: particle vs wave explanation
Replies: 25
Views: 3716

Re: particle vs wave explanation

Moose Hole wrote:Just out of curiosity, has anyone tried the two slit experiment with baseballs? I'm curious if it forms an interference pattern as well.

Baseballs no. Buckyballs yes.
by ATCG
Thu Oct 14, 2010 12:24 am UTC
Forum: Science
Topic: Mechanical limits of the human body.
Replies: 6
Views: 1115

Re: Mechanical limits of the human body.

DoD and NASA have performed many aeromedical studies on human limits. The work of investigator/guinea pig John Stapp is especially noteworthy. The FAA (aviation safety), NHTSA (automotive safety) and other DoT agencies might also have relevant data.
by ATCG
Thu Sep 23, 2010 6:38 pm UTC
Forum: News & Articles
Topic: Completely new and science fictiony weapon developed.
Replies: 68
Views: 7821

Re: Completely new and science fictiony weapon developed.

The idea of industrial sabotage via software has some precedent.
by ATCG
Thu Sep 16, 2010 6:25 am UTC
Forum: Logic Puzzles
Topic: The Four Commanders
Replies: 30
Views: 6028

Re: The Four Commanders

EDIT: Further spoilered: I believe the OP is trying to present the Byzantine Generals' Problem , first proposed by Lamport, Shostak, and Pease . As aleph_one notes, the solution depends critically on whether or not messages can be forged. In the case of forgeable messages: the problem is solvabl...
by ATCG
Mon Sep 06, 2010 6:50 am UTC
Forum: Coding
Topic: Help with bitwise operators
Replies: 20
Views: 10267

Re: Help with bitwise operators

I very much like the direction you've taken with your logicalNeg function. (I would like to think that I would have come up with it myself, but I suspect I wouldn't have.) Your fundamental approach to detecting x == 0 is sound; it's just the execution that doesn't quite come together. Consider repla...
by ATCG
Wed Sep 01, 2010 5:50 am UTC
Forum: Computer Science
Topic: Basic logic circuit
Replies: 6
Views: 1573

Re: Basic logic circuit

What you have is an example of relay logic or ladder logic - and the interpretation that squareroot has given is correct.
by ATCG
Sun Aug 29, 2010 4:49 am UTC
Forum: Science
Topic: Peaceful, but Mad, Uses of Nuclear Weapons
Replies: 76
Views: 7696

Re: Peaceful, but Mad, Uses of Nuclear Weapons

The Pantex Plant, near Amarillo, Texas, has been disassembling nuclear weapons for years. Meanwhile, the Russians are dismantling a significant fraction of their nuclear stockpile. Interestingly enough, their idea of how to best secure the special nuclear material in these retired devices is to ship...
by ATCG
Thu Aug 26, 2010 6:59 pm UTC
Forum: Science
Topic: Peaceful, but Mad, Uses of Nuclear Weapons
Replies: 76
Views: 7696

Re: Peaceful, but Mad, Uses of Nuclear Weapons

All these ideas clearly fall short of being the sort of visionary achievement that only a mad scientist could dream. How about an orbital underground subway system between NY and LA? Ted Taylor beat you to this idea - minus the orbital part - by a number of decades. I suspect that he would have obj...
by ATCG
Fri Aug 20, 2010 4:33 pm UTC
Forum: News & Articles
Topic: P≠NP
Replies: 69
Views: 12003

Re: P≠NP

Jesting, your "bad news" with circuits isn't quite as final as one might think. Solving arbitrary instances of SAT is in NP, but we don't build arbitrary circuits. In practice, we can build circuits that are easy to reason about, rather than random ones or ones that are hard to reason abo...
by ATCG
Thu Jul 22, 2010 5:41 am UTC
Forum: Science
Topic: Charge Sensor
Replies: 5
Views: 1007

Re: Charge Sensor

An electrometer might fill the bill for the OP.
by ATCG
Sat Jul 17, 2010 5:20 am UTC
Forum: General
Topic: How much helium is required to lift a human?
Replies: 16
Views: 4728

Re: How much helium is required to lift a human?

How can this thread have existed for two days with no mention of the late, great Larry Walters, aka Lawnchair Larry? (Safety tip: Don't drop your pellet gun.)

The OP might find useful information here.
by ATCG
Tue Jul 13, 2010 8:28 pm UTC
Forum: News & Articles
Topic: Teen steals airplane, flies to Bahamas?
Replies: 47
Views: 5718

Re: Teen steals airplane, flies to Bahamas?

6'5 is a big kid, I'm surprised he didn't accidentally engage the brakes. Well, he'd be tough to shoehorn into a Cessna 152. But I know for a fact that you can stuff a 6'8" NBA player into the front seat of a Cessna 172 without interfering with the controls (rudder pedals included) - if you mo...
by ATCG
Fri Jul 09, 2010 4:07 pm UTC
Forum: Science
Topic: Insider Science Jokes/Lingo
Replies: 129
Views: 28564

Re: Insider Science Jokes/Lingo

Beer makes paleontology better. When Nicholas Longrich discovered a new dinosaur species with a heart-shaped frill on its head, he wanted to come up with a name just as flamboyant as the dinosaur's appearance. Over a few beers with fellow paleontologists one night, he blurted out the first thing tha...
by ATCG
Thu Jul 08, 2010 3:19 pm UTC
Forum: News & Articles
Topic: 1 W laser pointer hits the market.
Replies: 228
Views: 71920

Lucasfilm hits Wicked Lasers with cease-and-desist

Lucasfilm Ltd. has sent a cease-and-desist letter to Hong Kong-based Wicked Lasers, threatening legal action if it doesn't change its Pro Arctic Laser series or stop selling it altogether. "It is apparent from the design of the Pro Arctic Laser that it was intended to resemble the hilts of our...
by ATCG
Thu Jul 01, 2010 6:28 am UTC
Forum: Science
Topic: Cannot Send Information Faster Than Light
Replies: 70
Views: 8848

Re: Cannot Send Information Faster Than Light

ok um stupid question but if you can't tell whether a particle has been entangled, how do we know entanglement really exists? Not a stupid question at all. As you say, correlation between widely separated events is not in itself terribly interesting. Showing that "an intervention at one place ...
by ATCG
Sun Jun 06, 2010 1:07 am UTC
Forum: Hardware
Topic: Noninverting amplifiers and measuring resistance
Replies: 10
Views: 2629

Re: Noninverting amplifiers and measuring resistance

The single most useful principle I ever learned about op-amps is the notion of virtual ground . To a good first-order approximation, the op-amp in your circuit will do everything in its power (so to speak) to make the voltages at its positive and negative inputs be the same. Assuming that your 1.225...
by ATCG
Fri May 14, 2010 4:10 am UTC
Forum: Mathematics
Topic: Higher Order Unprovability
Replies: 3
Views: 1612

Re: Higher Order Unprovability

You're right. Any sound theory subject to Gödel's first incompleteness theorem must have a true \(\Pi_1\) sentence it cannot prove: its own Gödel sentence (or equivalently, the canonical assertion of its own consistency). As you say, this stands in contradiction to what Zach (and his commenter) seem...
by ATCG
Wed May 12, 2010 7:41 am UTC
Forum: Mathematics
Topic: Higher Order Unprovability
Replies: 3
Views: 1612

Re: Higher Order Unprovability

It's late and your question makes my head hurt. In revenge I'm suggesting you read this article with special attention to Per Martin-Löf's argument on page 14. Maybe the statement, "The statement X1, and (for all values of N) the statement XN, which states that XN-1 is unprovable, seem to be un...
by ATCG
Sat May 08, 2010 3:31 pm UTC
Forum: Mathematics
Topic: Can we truly prove anything?
Replies: 86
Views: 11417

Re: Can we truly prove anything?

I believe Godel once proved that it is impossible for a logical system to prove it's own consistency. This is not really what the Incompleteness Theorem says. I know this. I just thought it was Godel who also proved this. I suspect t0rajir0u was objecting to the misstatement of Gödel's Second Incom...
by ATCG
Fri May 07, 2010 6:29 am UTC
Forum: Mathematics
Topic: Can we truly prove anything?
Replies: 86
Views: 11417

Re: Can we truly prove anything?

If you could do infinitely long proofs, there is a proof that PA is consistent in PA. But we're finite beings and proofs are defined to be of finite length. It's certainly true that we can't write out infinitely long proofs. But what we can do is treat proofs, even those of infinite size, as mathem...
by ATCG
Sat May 01, 2010 2:20 am UTC
Forum: News & Articles
Topic: Radio host sacked for rigging $10,000 competition
Replies: 5
Views: 1330

Re: Radio host sacked for rigging $10,000 competition

Hawknc wrote:Does this happen often in other places?

I don't know about often, but it happens. And if the perp is enough of a doofus, John Travolta may play him in the movie.

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