Wikipedia:Reference desk/Archives/Science/2017 August 8

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August 8

Escalators changing directions

One day the escalator is going up and the next day down. Why? Anna Frodesiak (talk) 02:13, 8 August 2017 (UTC)

Because somebody flipped the switch that reversed it's direction.--Jayron32 02:23, 8 August 2017 (UTC)

Excellent answer, Jayron32. :) Now, why did they flip that switch? Anna Frodesiak (talk) 02:32, 8 August 2017 (UTC)

In response to the Q, "Why did the Titanic sink ?", Jayron's answer would no doubt be "Because it was full of water." :-) StuRat (talk) 03:36, 9 August 2017 (UTC)

It's possible that they adjust the direction to match traffic flow. So, for example, if they have 3 escalators, they may have 2 going up and one down when people are coming into the building, and the reverse when they are leaving. Unlike changing the directions on roads, this operation should be fairly simple. Just put up a barrier blocking people from getting on, wait until everyone is off, then flip the switch and remove the barrier. StuRat (talk) 02:41, 8 August 2017 (UTC)

They might do this at large sports venues, for example. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:51, 8 August 2017 (UTC)

Yes, it's a standard thing to do at locations like that, and similarly in public transit stations where some escalators will run one way in the morning peak and the other way in the evening. (Details will depend on the traffic at the specific location, of course.) With the ones that I've seen, there may be a small sign telling staff what time each day to change it, next to the up/down switch (which is key-operated, by the way). But Anna says this isn't the case she's asking about. --69.159.60.147 (talk) 05:16, 8 August 2017 (UTC)

I'm not sure that's it. I see in lots of malls, a pair of escalators switching up to down and down to up. These are quiet malls with no traffic-flow reason to do this. Could this be about the gears and evening out wear from continuous single direction usage? Or is it psychological to shake up and wake up the people, or make them flow in a different direction when they disembark, like to make them see now products? Anna Frodesiak (talk) 02:58, 8 August 2017 (UTC)

They also switch up directions so that the escalators wear evenly. .--B8-tome (talk) 02:52, 8 August 2017 (UTC)

Edit conflict. I just guessed what you wrote! See above. Are you sure though? Thanks. :) Anna Frodesiak (talk) 02:58, 8 August 2017 (UTC)

If you want to be sure, you'll have to ask the building management people. --69.159.60.147 (talk) 05:16, 8 August 2017 (UTC)

Many modern escalators have sensors to detect people getting on. If no-one uses them for a while, they shut down, and re-activate in the useful direction when the next person gets on. --Stephan Schulz (talk) 12:41, 8 August 2017 (UTC)

Assuming that's true, it sounds like trouble waiting to happen. And what does it do if two people get on opposite ends at the same moment? ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:08, 9 August 2017 (UTC)

There is no such thing as two events happening "at the same moment" for a control computer. One or the other will win. If it goes your way, you grin apologetically at the other person. If not, you glare at them while you wait or use the stairs, which are usually next to the escalator. --Stephan Schulz (talk) 04:45, 9 August 2017 (UTC)

Metastability in electronics is an inevitable result of any attempt to map a time-continuous domain to a clocked one. Blooteuth (talk) 12:13, 9 August 2017 (UTC)

It will depend on the tolerances of the device. When I reset my cable box, I have to push three buttons at once, with two hands. I'm sure that I'm not literally pushing all three of them at the same moment, but it works. Also, I'd like to see a citation for someplace where escalators oscillate between up and down depending on where someone steps on it. I would think that customer irritation is a big price to pay for being too cheap to build a second escalator. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:55, 9 August 2017 (UTC)

Not a high-quality source, but a blog report from an expat living in Munich. These are totally normal in Germany in places with little traffic or in situations where traffic streams change depending on the time of day. Remember that Europe has public transport, and these are part of the infrastructure, not a luxury to impress customers ;-) --Stephan Schulz (talk) 21:45, 9 August 2017 (UTC)

The comments are good evidence for why it's a stupid idea. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:52, 9 August 2017 (UTC)

About as stupid as the idea that we don't all live in 40 room villas on beautiful mountain tops and commute to work from our personal airport in a custom 747. Or to build 6 lane highways where a 12 lane highway would avoid all traffic jams. In the real world, resources are limited and we tend to prioritise how we use them. Perhaps it's not yet clear: There always are normal stairs next to the escalator. Most people get to ride (because the escalator statistically follows the traffic direction), the others can wait or walk. Nobody is doomed forever... --Stephan Schulz (talk) 05:51, 10 August 2017 (UTC)

The comments in that blog illustrate why it's a stupid idea: it aggravates people. It's typical European authoritarianism: Here it is, live with it, get used to it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:56, 12 August 2017 (UTC)

When you push those 3 buttons, the device registers the fact that each is being held down continuously. That is totally different from the situation we're talking about here, where a device reads the state of each escalator's infra-red detector in turn. Only one will be successful, even if another one is triggered a fraction of a microsecond after being read and before the reading of the other. Polling on a rotational basis like that can result in only one being first. This is the basis of all computer programs which run through a set of commands and loop back to the start. No two commands can be read at the same time because the reading of them is timed in rotation by the system clock. Akld guy (talk) 21:21, 9 August 2017 (UTC)

What's your evidence for how cable boxes work? ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:50, 9 August 2017 (UTC)

I've been reading and thinking about this up/down phenomenon. I would like to add something. It is all over the city in different malls. And it may be just disorganized workers. The person who turns the key each morning may be different on different days. He turns the key maybe left, maybe right. If it goes up, then he makes the other go down. No system. That would fit where I live perfectly. There's probably a rule for this -- something like Occam's razor or Hanlon's razor. Then again, I could see (I suggested this above) shops at the foot of an escalator asking management to make people disembark there to attract more customers. Anna Frodesiak (talk) 08:42, 11 August 2017 (UTC)

Do escalators follow the rule of the road? That is, in this country at the point you board the escalator the one running in your direction of travel is usually on the left as you face it. 79.67.91.37 (talk) 10:45, 12 August 2017 (UTC)

No, they do not, not in China anyway. :) Anna Frodesiak (talk) 11:09, 12 August 2017 (UTC)

(edit conflict)And again, on the London underground the rule is "stand on the right", i.e. traffic is flowing on the left hand side. This shows the convenience of the "keep left" rule on the highway, since it is more convenient for right - handed people (the majority) to grip the handrail with the left hand while holding and manipulating the ticket with the right. 79.67.91.37 (talk) 11:14, 12 August 2017 (UTC)

Neuroscience question

Is it possible to remove consciousness (like the feeling of under anaesthetic), but keep your body alive and functioning normally in everyday life? I.e. is it possible to turn a person into a meat machine? Why does consciousness even exist? If materialism is correct there shouldn't be any consciousness. It would reduce a lot of suffering in this world if people can do this, unless dualism/idealism is correct. Money is tight (talk) 05:31, 8 August 2017 (UTC)

Vital body functions can remain alive when the patient is in coma, yes. Of course that is not the same as functioning usefully. Unconsciousness, coma, brain death and autonomic nervous system may be useful. As for the part about materialism and machines, it is indeed expected that neuroscience may eventually explain consciousness. Parts of consciousness are being understood but a lot remains to be discovered. You appear to infer that the source of consciousness would be a hypothetical soul or the like. We can invent such explanatory devices, symbols and concepts for things that are unknown. We also do this as part of science, but more rationally. Some hypothesize that the impression of self-consciousness is an illusion. Also see hard problem of consciousness, existence of God and problem of evil. —PaleoNeonate – 06:38, 8 August 2017 (UTC)

Maybe it is possible. If an evil scientist had selectively removed consciousness from half of the human race but left them functioning exactly as usual in all other respects (including stating that they were actually conscious when asked) then how could you tell ? See philosophical zombie. The materialist response is that a philosophical zombie is a logical or physical contradiction - like a three-sided square or dry water. Gandalf61 (talk) 08:24, 8 August 2017 (UTC)

An Induced coma by barbiturates such as Pentobarbital and Thiopental can be maintained (e.g. for brain surgery, 7-14 days with monitoring by an anaesthesiologist) with some risks which are noted here as: Myocardial depression, Increased in venous capacitance, Impaired gastrointestinal motility, Increased hepatic microsomal activity, Possible allergic reaction and Impaired immune response. Blooteuth (talk) 10:05, 8 August 2017 (UTC)

Why focus strictly on materialism? That is a subset of desire, which is one of the four noble truths. 209.149.113.5 (talk) 15:02, 8 August 2017 (UTC)

You may be confusing ontological materialism with economic materialism. Gandalf61 (talk) 15:15, 8 August 2017 (UTC)

Materialism and consciousness are friends. People who formulated materialism had consciousness. --AboutFace 22 (talk) 16:04, 8 August 2017 (UTC)

That's only trivially true. They also had pancreases and eyebrows and mothers, but that doesn't mean that knowing that leads us to a deeper understanding of materialism. Post hoc ergo propter hoc and all that jazz. --Jayron32 16:11, 8 August 2017 (UTC)

There is no problem of understanding materialism. There is a problem of understanding idealism and religions. I subscribe to the quantum theory of consciousness[1]. --AboutFace 22 (talk) 16:41, 8 August 2017 (UTC)

Which is no less based on a pure-faith belief than any other religion, except it uses sciencey words so it makes the athiests feel better. --Jayron32 18:38, 8 August 2017 (UTC)

I wouldn't say that athiesm requires justification, or that quantum mind is pure faith, but it is pseudoscience (or at least, a far fetched hypothesis for now). —PaleoNeonate – 20:22, 8 August 2017 (UTC)

Or just give up on materialism and accept that there only exist a mathematical multiverse. This is a set of all algorithms, one of these algorithms will be me at precisely this moment when I'm writing exactly this part of this sentence. Another algorithm is me a few seconds later writing this part of the next sentence. And yet another algorithm is Jayron32 writing to AboutFace 22 that what he says is no better than any other religion. Note here that the algorithms contain all the information about what the person (or some other entity) is aware of, it doesn't imply the existence of an external world, it encodes the external world indirectly as that's contained in whatever the person is aware of. Count Iblis (talk) 20:18, 8 August 2017 (UTC)

solipsism Gem fr (talk) 13:17, 10 August 2017 (UTC)

See Zombie#Haitian_tradition. This holds that it is possible, by use of a psychoactive substance, to disable their decision making processes, rendering them highly susceptible to suggestion. Not medically verified to be true, though, perhaps because voodoo priests/priestesses tend to be highly secretive about their methods. (This tradition also holds that zombies rise from the dead, but far more likely they were just in a deep coma from the substances ingested, noting that in Haiti the air temp and body temp are often close, so as to make determining death by body temperature impossible.) StuRat (talk) 04:16, 9 August 2017 (UTC)

Your question cannot be answered without a proper definition of consciousness and "normal everyday life". You'll find Self-awareness of interest, i guess.

"If materialism is correct there shouldn't be any consciousness" is quite a strong assumption, why would you believe that? Gem fr (talk) 13:17, 10 August 2017 (UTC)

The question sounds like the questioner is reifying conciousness - probably they believe in something like a soul that might be removable. But this is a belief we don't need to deal with to answer the question; the behaviors of people who take Ambien or who sleepwalk demonstrate that all sorts of complex behaviors are possilble while unconscious. - Nunh-huh 21:08, 10 August 2017 (UTC)

Who said sleepwalkers aren't conscious? And as for the materialism no consciousness thing, it's intuitive that in a Newtonian materialistic world there should be no consciousness (which has lead people like Dennett to believe consciousness is just an illusion). I'm saying, if materialism is correct we must be able to turn off consciousness, and that would reduce so much suffering (maybe because I've been through so much myself, I wish I had an on/off switch to my consciousness). Money is tight (talk) 02:39, 11 August 2017 (UTC)

The problem is that you, and some respondents, have conflated two discrete meanings of the term "conscious" which might as well be considered little more than homonyms for purposes of this sort of discussion: 1) the general topic of the sensation of subjective experience, and 2) the concept of the much narrower state of mind of being "awake", a specific experience which in every day dialogue we treat as "more real" or "more conscious" than other states of mind we spend our life in. Your answers (such as exist) vary a little depending on which definition were are utilizing in parsing the questions themselves. I'll answer your originally inquiry shortly, when I have time to spare.

As to the somewhat separate issue of a mechanistic Newtonian universe precluding consciousness as an objectively real phenomena, that's a complex topic, but suffice it to say that while it may seem like an intuitive assumption to you, experts (be they cognitive scientists or metaphysicians) are far from settled on the matter--to say nothing of people generally, of course! I also agree that you don't seem to be adequately explaining the intermediate causal relationships that lead you to believe that materialism is incompatible with the view that consciousness is in fact a "real" phenomena, albeit one that is poorly understood in physical terms at present. If you are referring to the hard problem of consciousness, then yes, that's a real quandary. Well, that's an understatement, actually. It's probably in fact the greatest quandary in the history of human inquiry. But not all researchers or philosophers agree that it's established that consciousness is not an empirical reality, however confusing the question of how it arises out of physical matter. And I think it's more accurate to say that Daniel Dennett claims not that consciousness doesn't exists in any sense, but that the nature of the questions we ask about it are often non-pragmatic/unuseful. Snow ^{let's rap} 09:15, 11 August 2017 (UTC)

Not sure I understand what you mean, but it seems to me that booze, drugs and even sleep are fairly common and effective ways to "to turn off consciousness", and "reduce so much suffering" (or at least try to, i am not sure it works very well in this respect...), so obviously consciousness needs a material element to function, for sure.

I am pretty sure that "suffering" is a word that can be applied to unconscious beings (like an oyster being eaten alive, or a comatose human), so turning off consciousness wouldn't work.

As far as i understand Buddhism, it even say that suffering is consequence of LACK of consciousness, not too much of it (please correct me if wrong). In fact, AFAIK, all spiritual ways tries to reach some higher level of consciousness as a way to reach real happiness, prevent or fend off sufferings.

Gem fr (talk) 10:32, 11 August 2017 (UTC)

I think you're going to find that perspectives vary considerably between particular traditions and idiosyncratic perceptions, when it comes to such spiritual matters. For a certainty, there are strains of Buddhism that would argue that the "higher level" consists of letting go of the notion of subjective experience, and the illusion that one is a separate thing for the rest of reality. And indeed, some perspectives might even find the notion of qualia and perception of the physical world to be a trap. These issues are a matter of longstanding debate in certain ascetic traditions, needless to say.

As to the other, much more (well, ok, slightly more) empirical matter, I don't think most neuroscientists would agree with you that an oyster is a fundamentally "unconscious" creature, when we are looking specifically at the issue of pain. It has a nervous system with both internal and external sensory inputs. It has a rudimentary kind of consciousness, or at least is presumed to in the way most animals with such biophysical systems are assumed to. It may not include anything approaching the human capacity for abstract knowledge or even the sensorium/level of outward perception/sense of experience of an animal of intermediate neural complexity (let's say, for example, a bee), but it presumably does "feel" in respects other than pain. Snow ^{let's rap} 11:02, 11 August 2017 (UTC)

Sure oysters feel; Scallops can even see (a rudimentary sight, indeed, but a sight anyway). I am just pretty sure OP doesn't consider these as "conscious", since according to his question consciousness may not be not required to live a normal life. Then again, a proper definition of consciousness is lacking. Gem fr (talk) 11:43, 11 August 2017 (UTC)

This also reminds us that nervous systems evolved (evolution of nervous systems, evolution of the brain, evolution of human intelligence) along with bodies for a long time (so did neurons before and after complex nervous systems existed), making hypotheses like quantum mind or higher souls which require an advanced level of sentience to possess/assess, less likely. Animal cognition is also interesting... —PaleoNeonate – 14:00, 11 August 2017 (UTC)

You can also turn this around and start with sensations, consciousness and then consider the problem of localizing yourself in some state given everything you aware of. So, given what I experience right now, I can locate myself in a place where there exists a human body that I consider to be me that's typing this sentence in a computer that's logged into Wikipedia. But the far more rudimentary consciousness of an oyster probably won't be precise enough to locate itself as being inside the body of an oyster at roughly the place and time as we can observe it. It could just as well be some other similar creature swimming in an ocean on a planet similar to Earth. In case of humans, if the universe is large enough or if there exists a multiverse, then we'll have copies in places that need to be far more similar to our current location, what matters is that we are not aware of the difference.

This then means that consciousness cannot be attributed to the precise microstate of the system, as the conscious experience does not contain enough information to locate itself in a precisely defined physical state. Count Iblis (talk) 18:36, 11 August 2017 (UTC)

Cooling a CCFL bulb without straining the glass

I want to make a floodlight from salvaged CCFL lamps. Despite their name, they do generate heat and I'm going to be using them in high-density so I need to cool them (their efficiency drops off beyond about 30 °C) and I'd like to do it passively if possible (mostly because of the noise). The way I'm considering doing this is affixing the glass tubes to an aluminium panel (thickness not determined), possibly using thermal adhesive or possibly a cheaper adhesive. My concern is that with cooling on one side of the glass tube, it could lead to stress and fracturing which would destroy the tube. Is that a valid concern? --145.255.246.78 (talk) 06:23, 8 August 2017 (UTC)

Yes it's a valid concern. Consider immersing the lamps in a transparent oil. Blooteuth (talk) 09:43, 8 August 2017 (UTC)

I am not an expert, but perhaps immersing high voltage devices in oil could give rise to some safety or reliability concerns ? Gandalf61 (talk) 10:13, 8 August 2017 (UTC)

Oil immersion is commonplace for high voltage transformers and contact breakers. Blooteuth (talk) 11:45, 8 August 2017 (UTC)

Indeed. But the fact that some high voltage devices are designed to be immersed in oil does not give me confidence that taking some other high voltage device that is not designed for this and immersing it in oil is either safe or sensible. Gandalf61 (talk) 12:28, 8 August 2017 (UTC)

Oil is a poor coolant for this task. In large devices, it circulates and the heat transfer is by convection. Here you need something that's useful by conduction. There are such thermal tapes available, they're now widely used for mounting COG (Chip On Glass) LEDs onto aluminium heatsinks. They're also slightly flexible, to avoid straining the glass. Andy Dingley (talk) 14:47, 8 August 2017 (UTC)

^^ That is the answer, I think, but I'm rooting for one of those misting devices they use for produce at Wal-Mart. You would try to make sure the ends are sealed up and then you have a flooded floodlight dripping gentle shining warm ?high voltage? rain. Would look really cool... Wnt (talk) 18:32, 8 August 2017 (UTC)

I guess you're joking but I'd still like to understand what you're saying. The misting device would be fed oil that leaks from the enclosure? In any case, I was thinking of using thermal adhesive from a tube to adhere the glass CCFLs to the aluminium sheet. I figure that will be much thinner than using even a 0.5 mm thermal pad. --145.255.245.164 (talk) 22:08, 9 August 2017 (UTC)

Well, I was thinking if you are talking about oil, why not water? In theory, the electrical bits can be insulated, and if the mist is fine enough, the water shouldn't impose large temperature variations. And of course a water line can keep flowing at a high rate to keep cooling things down. Wnt (talk) 00:30, 10 August 2017 (UTC)

Glass is a thermic isolator. Aluminium alloys have a typical Thermal conductivity (W·m⁻¹·K⁻¹) of over 100. Glass has a typical thermal conductivity of 0.5 - 2! Thus you can not use glass as part of a heat "bridge" or cooling "chain". It does not matter much if you cool the glass with aluminium, copper or graphene. Its like putting a stretch of plastic between 2 copper cable ends and then ask if the electric current would improve if you would use gold contacts on the plastic ends. --Kharon (talk) 11:30, 8 August 2017 (UTC)

The glass is non-negotiable since the body I want to cool is made of glass. Attaching it to an aluminium sheet with some heatsink attached would maintain a temperature gradient. One option is glass and aluminium and the other is glass and air. The aluminium would greatly increase the surface area in contact with air. 129.215.47.59 (talk) 14:48, 8 August 2017 (UTC)

The quoted thermal conductivity of glass is 0.8 to 0.93 W·m⁻¹·K⁻¹ A (disputed) diagram at the article Thermal conductivity shows it relative to other materials. Blooteuth (talk) 12:08, 8 August 2017 (UTC) (edited after vandalism Blooteuth (talk) 11:57, 9 August 2017 (UTC))

The best way to keep the tubes cool would be to allow natural convection between them. What orientation will you have them in? Dbfirs 12:53, 8 August 2017 (UTC)

They will be arranged all in parallel. I made this useless animation to try to compare active versus passive approaches. Since I want these floodlights to illuminate my dumb YouTube videos (in progress), I don't really want the noise of the fans. I'm planning on having 50-70 in parallel, representing about 200-300 W of heat yet I need to keep them below 60 °C maximum (40 °C would be better) 129.215.47.59 (talk) 14:48, 8 August 2017 (UTC)

Will they be horizontal or vertical ? I would expect convection to work better if they were vertical, provided there is a sufficient air gap between each tube, it's neighbors and the housings.

As for fans, they can be made to be silent, provided they are large and slow moving. I have large box fans hooked up to a dimmer switch so I can reduce the speed and hence noise down to a whisper. StuRat (talk) 02:53, 9 August 2017 (UTC)

If the floodlight project is for making videos, I suggest first checking with your video camera whether CCFL illumination is adequate regarding flicker and colour rendition. Blooteuth (talk) 12:03, 9 August 2017 (UTC)

I probably won't go through the hassle to make my own floodlight, but, anyway...

I very much doubt that you will cool the lamp by gluing them to an aluminum panel, video projectors would have used this kind of system if it worked. Speaking of which, this article has DIY links, that cope with the very same cooling issue that you have (same power range), so you will find them of interest (e.g. [2] ).

You could find interest in computer fans a,d computer fan#Alternatives, to, as they do the job of pulsing away 100s W without uncomfortable noise

Gem fr (talk) 12:54, 10 August 2017 (UTC)

Lard diet

I've been reading about "no carb" diets and I was wondering how long could a human survive eating nothing but lard? — Preceding unsigned comment added by 190.117.188.223 (talk) 09:40, 8 August 2017 (UTC)

As long as it takes for one of these diseases to kill you. It's probably somewhat variable based on your particular biology, but you'll die of one of those. --Jayron32 10:51, 8 August 2017 (UTC)

Are you sure of that? I can't help wondering if Kwashiorkor or some effect of protein deficiency will kill you first, especially for a child. And what about Mineral deficiency? This may depend on your precise water and lard, but what about a sodium or potassium deficiency? P.S. I'm assuming that this isn't excluding drinking water since I suspect you'll probably quickly die of dehydration if you only eat even unrendered lard and don't drink anything. Nil Einne (talk) 15:53, 8 August 2017 (UTC)

That'd work too. There's lots of ways to day of malnutrition. --Jayron32 15:58, 8 August 2017 (UTC)

Or even ways to die of malnutrition tomorrow ; -) Aspro (talk) 18:21, 8 August 2017 (UTC)

Pronounce "day" the Aussie way and it works. ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:45, 8 August 2017 (UTC)

I believe that you would die of Hyponatremia before any of the other conditions mentioned gets you. Under the right conditions, [3] severe, life-threatening hyponatremia can occur in a matter of hours.[4] Too-rapid restoration of normal sodium levels may also cause trouble.[5] --Guy Macon (talk)

Wouldn't the hyponatremia be due to a sodium deficiency arising from insufficient dietary intake? Assuming as I said above they had a sufficient but not excessive water intake and weren't trying to run a marathon or something. Yes it may not normally be the sole cause, but it seems to me it would be in this case. Nil Einne (talk) 04:16, 9 August 2017 (UTC)

You'll survive longer on blubber. Count Iblis (talk) 20:25, 8 August 2017 (UTC)

fasting, starvation and Starvation response will be of help. specially Starvation response#timeline and Starvation response#Biochemistry

You can survive several month on your own lard ("fasting" as several examples), the lifespan will depend on your health and what you drink, since it will bring some of the necessary nutrients (like aforementioned sodium).

according to Starvation response#Biochemistry, death occurs when you run out of energy (fat) or, when fatty enough, of proteins; you usually have enough micro-nutriments (vitamins, mineral, etc.) to don't run out of these (also the lack of them will make you more susceptible to death by disease). Obviously eating lard will ensure you only die out from a lack of proteins, so the best answer is probably "longer than if you don't eat lard, but not much".

Gem fr (talk) 12:05, 10 August 2017 (UTC)

Ventricular fibrillation by palpation

Not a medical request, just curiosity Is it possible to detect ventricular fibrillation by chest palpation instead of electrocardiogram? Would the palpating person sense quivering instead of beating? 212.180.235.46 (talk) 17:10, 8 August 2017 (UTC)

Some people arrive at the hospital with a chief complaint that indicates they are feeling the effects of arterial fibrillation. Descriptions I've heard are skipping a beat, hearing a thud, or just chest pain. Ventricular fibrillation is different. With ventricular fibrillation, the heart pumps little to no blood. Cardiac arrest and unconsciousness follows very quickly. Therefore, I seriously doubt the person will be able to say what they felt. Of note, there will be no transfer of short-term memory to long-term memory. So, they will have no memory of the few minutes before losing consciousness. Therefore, they will not be able to describe what they felt. 209.149.113.5 (talk) 17:39, 8 August 2017 (UTC)

[1] you mean atrial fibrillation, not arterial. [2] the questioner seems to be asking if a second person (that is, the examiner, rather than the person with ventricular fibrillation him or her- self) could detect ventricular fibrillation. A person with ventricular fibrillation would be pulseless, but this is usuallly determined by palpating an artery rather than the heart per se. And there are other pulseless rhythms (pulseless electrical activity). Generally, if someone is in ventricular fibrillation, the examiner will be more interested in hooking them up to a monitor/defibrillator than in practicing their palpation skills. - Nunh-huh 18:05, 8 August 2017 (UTC)