Wikipedia:Reference desk/Archives/Science/2012 May 7

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May 7

Most specific term for the misleading sensation I am feeling

I can't quite explain the sensation I am referring to, but loosely-speaking it is "the sensation of being in the specific room that happened to be my bedroom approximately ten years ago".

Yes, I am on drugs, which probably explains why I am feeling said sensation. But I am not on a hugely strong deluriant or anything; indeed I wouldn't have expected to have this sort of unusual sensation. But it's very strong indeed, hence my starting this discussion. Said room was approximately twice the size of this room, had a different shape (was "in the attic" so sloping on two sides) and with windows in different locations. Also I'm in Ballabeg, Isle of Man while said room was in Ely, Cambridgeshire. I can't actually see anything as my light is out and the laptop I'm typing this on, which is on my chest, is saturating my vision. So it's all about sensation.

All quite peculiar and one of the reason I advocate to everyone that they take hallucinogens (not that I have taken any today) as otherwise their only hope of feeling these very peculiar things is random occurrences like this - which I probably wouldn't have even noticed save for my hallucinogenic experience. And btw none of the drugs I have taken "ought" to produce symptoms like this, but they may have made me more receptive to them. I went to the toilet during typing this out and of course was fine when I had visual evidence of what was going on.

So... again - please do describe, as precisely and concisely as possible, what's happening to me

Grazi,

Egg Centric 01:30, 7 May 2012 (UTC)

Sounds like drug-enabled deja vu to me. The memory-based explanations section of the article sounds pertinent to me, if you're asking about why the brain is triggering these odd sensations. Soapbox: Here's the thing about drugs: they are just ways to add chemicals in your brain. Your sense of everything in life — all that is what you call "reality" — is also produced by chemicals in your brain. So you're playing with the balance of chemicals in your brain. The effects of some chemicals are fairly predictable — alcohol in your system will probably react more or less the same way each time, though each time it's in your blood (and thus your brain) it's going to be playing with other variables of your current state (emotions, for example). But other chemicals can have far more complicated interactions. Anyway, the point is, one should not be too impressed with whatever subjective states are created by playing with the brain chemicals — weird sensations, funny colors, amusing or terrifying notions, whatever. They're all just manifestations of the chemicals. That's all. Completely boring and material. That they can plugs into memory centers in funny ways, or plays with your vague sensations, is not that interesting except as a reflection of the ultimately chemical nature of your brain, the organ that interprets sensations. The most impressive thing about hallucinogens, in my experience, is that it takes only milligram levels of certain chemicals to make your reason-box go completely haywire, to start feeding you completely bonkers versions of reality. The subjective states themselves are, to me anyway, less interesting than most dreams. --Mr.98 (talk) 02:14, 7 May 2012 (UTC)

Surely you jest. To block the inhibition of perception reveals tremendous beauty in many ordinary things, and this is a lesson people can learn from. But there are risks... some fairly well established, others beyond the familiar realms of science. Wnt (talk) 06:02, 7 May 2012 (UTC)

I've yet to see too many deep insights come out of the "beauty of ordinary things" approach. These things feel profound when you're on them, but in the morning they all look like "What's nausea but a kind of -usea?" which isn't very impressive. What's impressive to me is that a milligram of the right substance and reality goes out the window — that our grasp on basic cause and effect is so tenuous, so frayed. That drugs can make you feel that like, dude, pants are so arbitrary, and kissing is such a weird idea, seems subversively brilliant at the time but those aren't that deep of insights. --Mr.98 (talk) 11:51, 7 May 2012 (UTC)

Taking halucinogenic drugs is a very bad idea - it is well known they can scramble your brain. A well known example is Timothy Leary - who started out a highly intelligent and articulate academic and ended up, after taking LSD, a clown you could not have a sensible conversation with.

Your experience may be a form of flashback http://en.wikipedia.org/wiki/Flashback_(psychology). It is well known that hallucinogens, from drugs with very mild hallucinogenic effects, like cannabis, thru to strong ones like LSD, cause flashbacks long after the main effects have long worn off. Flashbacks can even occur months or even years later.

Having said that, your experience is not at all unusual, even for people who are dead boring normal and have never taken any sort of drug. It is quite normal to occaisonally get a sensation, when in a very dark room, of being in a much larger room. I myself sometimes have this sensation when laying half awake in bed in the morning, or if I awaken during the night. As soon as I move to get out of bed, or turn on a light, the sensation immediately goes. Some small children require a dim light in their bedroom - they get distressed as they know they are in their bedroom, but they have the sensation that the walls have receded into the distance, and it scares them. There is a medical term for this, but I can't remember it right now. I'll re-post if it comes to me.

Wickwack58.169.254.40 (talk) 02:30, 7 May 2012 (UTC)

According to Lysergic acid diethylamide#Flashbacks and HPPD flashbacks aren't actually a recognized medical syndrome; they can arise from a number of memorable experiences. But there are visual symptoms which can be more disturbing. Of course, this is not what the original question is about. Wnt (talk) 05:54, 7 May 2012 (UTC)

You vastly overstate Timothy Leary's incomprehensibility, even into old age. He was highly-intelligent and articulate until his death. While taking regularly high doses of LSD (as Leary did for decades and decades) may have long-term effects (our article points out that this is not at all well-established by science), I think stating that occasional uses of such chemicals "scramble your brain" is overstating things quite a bit. You may want to reexamine what you have been told, because it is wrong in every respect. --Mr.98 (talk) 11:51, 7 May 2012 (UTC)

Mr. 98, in your post beginning I've yet to see too many deep insights, you were spot on. But you need to think before you write in response to others. You don't read carefully what others have written. You provide links to make your words look good, but the material you linked does not support what you are saying. I checked the Leary YouTube video. Within the first minute, he's said he went to 7 colleges and was expelled from several. That doesn't seem likely (Get expelled from one, and you can go to another. Get expelled from two, you can try another. Get expelled from 3 or more and none will take you on) and does not fit the known facts. And all that stuff about eyes in the later part of the video - its just boring nonsense that has meaning for only Leary and those like him. The interviewer had a conversation with Leary, but it was not a sensible one. Wickwack58.167.228.55 (talk) 01:23, 9 May 2012 (UTC)

That's interesting Wickwack. As the drugs I was on at the time do not usually have hallucinogenic effects I'm wondering if sleep depravation or similar may have cuased it. Do you notice a particular reason behind the times it happened for you? Egg Centric 23:50, 8 May 2012 (UTC)

I can't comment on whether sleep deprivation would do it, except to say it seems possible. I myself have not noticed any particular reason for the experience, and would not expect to. It just happens at infrequent random intervals. Wickwack58.167.228.55 (talk) 01:00, 9 May 2012 (UTC)

If you want the technical label, this is a type of delusional misidentification syndrome. It's not all that uncommon for people with amnesia or certain types of brain damage to show false beliefs about location. Looie496 (talk) 02:51, 7 May 2012 (UTC)

Wrong label. Neither what I was talking about, nor the OP's experience as he described it, is a delusion - he was clearly aware that his experience was in only one sensory mechanism, and he was clearly aware it was a false one. It is a halucination, not a delusion. And as explained, it clearly does not require, and does not indicate, brain damage. Wickwack120.145.56.245 (talk) 03:23, 7 May 2012 (UTC)

Nimur deleted the whole section as "medical advice"; clearly it isn't. We don't provide medical advice here, and some of the talk above about brain damage strays in that direction, but it's not very relevant. Wnt (talk) 05:40, 7 May 2012 (UTC)

Correct. I've removed the medical advice hat-ing cause it is no such thing. Egg Centric 22:13, 8 May 2012 (UTC)

This sounds like a "madeline cake" moment. Personally I get these sort of sensations quite often, sometimes several times a day. There's often an overt sensory cue, like the sunlight being just as it fell when I was in school at age 9, or beech leaves lying against a red-brick wall, but just as often there is no obvious link. One just feels that way, maybe because an emotional state meshes, or a thought, or the juxtaposition of two words. And it's certainly much stronger than a memory, but not hallucination or delusion, just the identity merging between the two life-points for a while. Rich Farmbrough, 02:12, 9 May 2012 (UTC).

For those not in the know, Rich's reference to madeleine cake (he spelt it wrong) refers to involuntary memory triggered by a particular stimulus. The term comes from author Proust http://en.wikipedia.org/wiki/Madeleine_(cake). It seems to me that the stimulus for Egg Centric's madeleine cake experience (if that's what it was) was the halucination of his room expanding that can occur thru sensory deprivation (the dark room). Note that the term "halucination" refres to a sensory experience, of any sort, that is not induced or caused by a real stimulus. It is not necessarily, and most often isn't, a bizare experience as may be caused by drug taking or brain damage. For example, an random itch on your skin, if not triggered by something touching you, is tecnically a halucination. Wickwack60.230.222.4 (talk) 02:54, 9 May 2012 (UTC)

how nuclear radiations caused pancytopenia?

Pnacytopenia is a disese There are many reasons for causing pancytopenia, nuclear raditions also one of the cause but i dont know How nuclear rays cause Pancytopenia?? If anybody know this so please tell me.. — Preceding unsigned comment added by 111.68.108.51 (talk) 07:55, 7 May 2012 (UTC)

Ionizing radiation, such as the radiation produced by certain nuclear reactions, is able to penetrate through a human body and mutate the DNA within cells. High rates of mutation cause a variety of effects in cells, including cell death. These effects are far more dramatic in rapidly dividing cells, such as those found in bone marrow. This results in a gradual reduction in the blood concentrations of all cells produced by bone marrow, leading to pancytopenia. Someguy1221 (talk) 08:25, 7 May 2012 (UTC)

Quantum Mechanics/Heisenberg Uncertainty Principle?

Hi, I'm having trouble understanding the mathematical equations for Heisenberg Uncertainty Principle page from Wikipedia as well as the Wave/Particle duality due to my mathematical understanding limited to Calculus I. What makes the ideas of quantum mechanics so fascinating. And if the given position of a particle is known, then the energy is unknown and vice-versa? Is there an actual value for both at a precise time, but we cannot measure it by the technological means we have today? Also, couldn't the tools used in the experiment alter the electron placement via electromagnetic fields or by some other means?

If anyone can just give the details on this experiment it would be great! — Preceding unsigned comment added by 98.231.19.48 (talk) 09:06, 7 May 2012 (UTC)

Momentum, not energy. Anyway, what the Heisenberg uncertainty principle means, practically speaking, is that any is that no measurements are physically possible, regardless of how awesome your technology is, that will reveal the momentum and position of a particle more precisely than is allowed by the equation. This is a fact, and it is experimentally verified. The meaning of this fact, its implications for the nature of particles/waves, is less clear however. To my knowledge, most physicists take a very literal view of the uncertainty principle, and maintain that until observed a particle/wave has neither a precise position nor a precise momentum, and that accurately measuring one means the other simply does not exist as a precise value (waves can be that way). A minority of physicists take the view that a particle may have a precise position and a precise momentum simultaneously, but that the act of measuring one alters the other to an extent that makes accurate measurement of both impossible (the De Broglie–Bohm theory is an example of such an interpretation). They also hold that this is a fundamental property of measurements, and cannot be circumvented by superior technology. Someguy1221 (talk) 09:45, 7 May 2012 (UTC)

Note that momentum is always the object of quantum effects. Electrons in their orbitals vary in units of the reduced Planck constant (hbar), the precise unit of angular momentum that the photon carries in its direction of motion (though it somehow carries another, not in its direction of motion). And the Heisenberg Uncertainty Principle is that an atom in space can't have its momentum known past hbar/2 - i.e., to the nearest hbar unit...

What I don't myself know for sure is ... is there any way to know that two particles have a linear momentum relative to one another more precisely? And if so... is it quantized in units of hbar? (But I think that's just the same as the electron case - i.e. that it is quantized, but the quantization doesn't predict the outcome beyond that level of resolution) Wnt (talk) 13:55, 8 May 2012 (UTC)

It is impossible to simultaneously measure both the momentum and position. To truly see why is inherently technical. The reason for this is that the eigenstates (or state of the system corresponding to an observed value) of the position operator are not eigenstates of the momentum operator. That means that the less the uncertainity that we measure the particles position, the closer it is to being in a single eigenstate of the position operator. A single eigenstate of the position operator when represented in the momentum picture again requires a linear combination of the momemtum operator eigenstates. There can be no point where it is in a known state in both representations because momentum and position don't commute. It is not a matter of technical limitations on our ability to measure. See Quantum state for more details. IRWolfie- (talk) 22:17, 9 May 2012 (UTC)

Philosophically, the idea that there are objective properties of the particle which you are passively observing (in a God-like omniscient way) is no longer applicable. There is no such thing as action at a distance; to observe something means you have to interfere with it in some way. If not actually poking it with your finger (which of course means bringing the electron orbitals of your finger into the area of the particle until the force between them is measurable), then you are bouncing a photon of some type off it; or you interfere with it using an electromagnetic field, or a gravitional field, or some such. More realistically, you have to drop the concept that you are observing something basic and fundamental about the particle, and fall back to the position that you do an experiment and you get an answer, period, and the answer you get depends on what you ask/do. But doing an experiment itself alters the situation; things which have been experimented upon are not the same afterwards, and subatomic particles are no exception, so you can't do two different experiments right after each other and assume that the answers you get were both true at the same time. To find out the position of a particle, you need to trap it, more or less, which of course will alter the momentum; to find out the momentum, you need to adsorb it onto something which will alter the position. More to the point, since the basic issue is more fundamentally from the wave-like nature of particles; to find out the position of a "wave" you want it to look kind of like a single pulse, the narrower the better. After all, how would you describe the position of a wave which extended uniformly to infinity in either direction? But to do so, Fourier analysis tells us that such a pulse would be the superposition of an infinite number of waves of different wavelengths, the more tightly located the pulse, the wider the spectrum of wavelengths. And since momentum is a linear function of wavelength, that means an infinite selection of momenta (momentums?). Conversely, to get a perfect measure of momentum, you need a single wavelength, and Fourier tells us that that would extend to infinity in either direction; thus no information on position. So it's a trade-off; the more precisely you specify the position the less precise the wavelength gets, and vice versa, in a mathematically well-defined way. Gzuckier (talk) 04:37, 12 May 2012 (UTC)

adding angular momenta in quantum mechanics (QM)

Texts on QM never make it 100% clear when one should use the Clebsch-Gordan coefficients approach to adding angular momenta and when one should use LS(Russell Saunders)/jj coupling. I have searched all the Wiki articles I can find on the subject and am still not clear about it HELP!! Ron Baskin — Preceding unsigned comment added by 109.152.200.254 (talk) 10:31, 7 May 2012 (UTC)

You can do the computations from first principles. Considering that you don't know what method to use, you should forget about using such methods, close your textbook, take blank piece of paper and do the computations by e.g. writing down the trivial equation for the state with the highest l and m in terms of the product state and then repeatedly applying L^(-) = Lx - i Ly on both sides. And then you find the state for the lower l's, by using that they must orthogonal to the subsspace spanned by the higher l states.

Only when you can do this without any difficulties, should you use CG or LS tables. Count Iblis (talk) 16:06, 7 May 2012 (UTC)

Alternatively, you could try both and see which is easier for the particular case. 71.215.84.127 (talk) 06:35, 8 May 2012 (UTC)

Generic lifts

Many smaller lift companies use generic fixtures (produced by supply companies such as Dewhurst, EPCO, and SCHAEFER), because they don't make their own fixtures. My question: Why? --84.61.181.19 (talk) 19:28, 7 May 2012 (UTC)

That would be an economy of scale issue. That is, it would be more expensive to create their own than to buy from others. For an example, think of how expensive it would be for you to make a car from scratch, versus buying one made by others. StuRat (talk) 19:35, 7 May 2012 (UTC)

Are all recent Stannah lifts generic lifts? --84.61.181.19 (talk) 19:38, 7 May 2012 (UTC)

Around 1980, many lift companies in my area (such as FHW, K&S, OSMA, Schmersal, and W&W) used a rectangular button. My question: Why is this button no longer used? --84.61.181.19 (talk) 19:54, 7 May 2012 (UTC)

I can't speak for lift manufacturers, but we wouldn't use that sort of button in a new design for two main reasons - the side elements that hold the button cap in place are very fragile and break off too frequently, and the incandescent bulb uses a lot of power and needs changing too often. But it was the only reasonably-priced illuminated button you could get 20 years ago. Tevildo (talk) 20:39, 7 May 2012 (UTC)

Who has manufactured the aforementioned rectangular button? --84.61.181.19 (talk) 10:53, 8 May 2012 (UTC)

The ones in the photo look very like Omron A3D switches, but that basic design is produced by most switch manufacturers. Tevildo (talk) 16:04, 8 May 2012 (UTC)

New control panel designs have no moving parts to wear out or collect grime. 84.209.89.214 (talk) 23:45, 8 May 2012 (UTC)

The oldest automatic slide doors in lifts in Germany are about 60 years old. --84.61.181.19 (talk) 10:58, 8 May 2012 (UTC)

Why are generic lifts hated by many lift filmers? --84.61.181.19 (talk) 14:09, 9 May 2012 (UTC)

Possibly due to Product placement. CambridgeBayWeather (talk) 06:11, 10 May 2012 (UTC)

Not exactly on topic but this is interesting: "A recent swab study on elevator buttons showed 2,210 colony forming units of bacteria per elevator button…" Bus stop (talk) 12:56, 10 May 2012 (UTC)

I wonder if they could invent a germ-free system. A few ideas:

1) Voice recognition. "FLOOR TWELVE", for example. Buttons would remain for backup use only.

2) Tiny electric eyes for each button. Just wiggle finger between the two extensions to select each floor.

3) UV light to sterilize panel when elevator is empty. StuRat (talk) 22:14, 12 May 2012 (UTC)