Wikipedia:Reference desk/Archives/Science/2015 August 25

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August 25

how can electromagnetic pulses escape from a neutron star's gravity field

Akbar mohammadzade--2.187.70.127 (talk) 05:36, 25 August 2015 (UTC)

Neutron star article explains that the escape velocity of a neutron star's gravity field is typically a third to one half the speed of light, so electromagnetic (do you mean "pulses"?) don't have a problem escaping the gravity field of a neutron star. Vespine (talk) 05:53, 25 August 2015 (UTC)

where the star radius be 20Km then the escape velocity of objects for 2*10^30 Kg neutron star mass will be 1.6*10^8 m/s more than 0.5 light speed .--Akbarmohammadzade (talk) 05:19, 26 August 2015 (UTC)

The escape velocity only reaches the speed of light in the case of a black hole...that's why it's "black" - finally, electromagnetic radiation (including light) can no longer escape. But a neutron star is nowhere near the density of a black hole, so light can still escape from it. SteveBaker (talk) 20:46, 26 August 2015 (UTC)

how is the lensing strength of any neutron star , and is there any such lens has been observed

Akbar mohammadzade--2.187.70.127 (talk) 05:45, 25 August 2015 (UTC)

• There is definitely a gravitational lens affect around neutron stars. Lensing occurs because of the warping of space-time caused by the presence of a massive object. Neutron stars fit that bill. In fact, if the radius of the star is small the density of the star will be so great as to trap photons in orbit allowing for the entire surface to be seen. For more information see our neutron star article. The part about gravitational lensing and photon trapping is under the properties section. --Stabila711 (talk) 05:54, 25 August 2015 (UTC)

Anything with gravity will produce a lensing effect to some extent, though detecting it is another matter. The lensing effect of our own sun is detectable (barely), but only because we are so close to it. The extreme examples of gravitational lensing described in our article are caused by the collective mass of entire galaxies or galaxy clusters. A single neutron star would produce a far weaker effect known as gravitational microlensing. However, with advances in imaging technology it has become possible to detect the microlensing effect of even relatively low mass objects like exoplanets (see Methods of detecting exoplanets#Gravitational microlensing). So it should certainly be possible to see the lensing around a neutron star. I can find papers online dealing with the theory behind imaging a neutron star in this way such as this one, but no reports of anyone actually doing it. Given that paper is from earlier this year and mentions zero observations of neutron star lensing, I suspect it has never been observed, or possibly even never attempted. Someguy1221 (talk) 05:10, 26 August 2015 (UTC)

Gravitational lensing has even been detected around our local star...the Sun. When Einstein first came up with Special Relativity, one prediction of that was that gravitational lensing would occur. The first solid proof that Einstein was right came from measuring how the position of a far distant star seems to move when the light passes close to the sun. Obviously, it's hard to see the star when it's sitting right next to the sun in the sky - so the measurement had do be done during a total solar eclipse. There were a couple of efforts to do that, and the second of them clearly showed that the light from that star was bent by the gravitational field of the sun.

So something very small and massive - like a neutron star - is going to be a far better lens than the sun, but even the suns' lensing effect is measurable with instruments available since the 1920's.

SteveBaker (talk) 20:40, 26 August 2015 (UTC)

Time travel

Is time travel possible?Sahil shrestha (talk) 14:32, 25 August 2015 (UTC)

Backwards? Not that we know of. Forwards? Yes. By the process known as time dilation one can technically travel forwards in time. This is actually the premise behind the Planet of the Apes movie. When someone travels much quicker relative to another person the time they experience is different. For example, if we were to travel in a spaceship near the speed of light to the next star system over and back, it is conceivable that everyone we know will be dead from old age by the time we get back. This phenomenon is already seen in small scale on the International Space Station. --Stabila711 (talk) 14:40, 25 August 2015 (UTC)

(edit conflict) Maybe, but probably not. See the Wikipedia article titled Time travel, which discusses the issue. Time travel into "the future" by means of time dilation is well established, but is still not "time travel" in the traditional fictional sense of "winking out" at our current time and "winking in" at a different time, it's just the well established consequence of special relativity that the rate at which time passes for an object is dependent on what speed it is moving relative to other objects. Time travel into "the past" is considered to be literally and conclusively impossible, excepting for some esoteric (and entirely unproven) particles like tachyons. --Jayron32 14:41, 25 August 2015 (UTC)

In addition to the good links above, Arrow of time might be of interest. Also recall we are all time traveling - very close to one second per second. SemanticMantis (talk) 14:47, 25 August 2015 (UTC)

Time flies like an arrow; fruit flies like a banana Edison (talk) 15:29, 25 August 2015 (UTC)

Why do Americans get completely stoned after having their wisdom teeth out

I've noticed on YouTube that every video of somebody acting high after having their wisdom teeth out is from America. Additionally, I had my wisdom teeth taken out in the UK and didn't feel high at all. Anybody know what drugs they use in the US and UK, and why they seem to be completely different? 2.102.185.43 (talk) 21:27, 25 August 2015 (UTC)

Dentists use Nitrous oxide, more commonly known as laughing gas, to perform procedures that do not require full anesthesia. It has some side effects of euphoria but everyone reacts differently to it. The videos you see on YouTube are the extreme. Normal reactions to NO gas wouldn't be popular so those aren't posted, it is only the really extreme cases that get the attention. When I had my wisdom teeth out my parents said I just slept all day afterwards. Not a word the entire time. I don't actually remember the whole event so I will have to trust them. That would make for a crappy video so nobody sees it. --Stabila711 (talk) 21:42, 25 August 2015 (UTC)

I don't thing NOX is commonly the sole anesthetic given for wisdom tooth removal in the modern USA. Dental extraction only vaguely mentions local anesthetic (which nitrous oxide is not).

This paper [1] says "Lidocaine with epinephrine was the primary local anesthetic" for wisdom tooth extraction in Helsinki, 1990-93. This paper [2] says general anesthesia is often used.

WP:OR - when I had mine removed (at a university teaching hospital), I followed the recommendation to use twilight sleep ( which includes morphine), as well as simultaneous NOX - quite the heady concoction! Oddly enough David_After_Dentist#Medical_explanation has some relevant references. I recall @DRosenbach: is a dentist and regular contributor here, perhaps he can share some more useful info about medications given in USA vs elsewhere. SemanticMantis (talk) 22:00, 25 August 2015 (UTC)

It is completely possible that something else is used by other dentists but I didn't have mine out too long ago (about 5 years now) and they used gas to knock me out. Had the mask and everything. In any case, YouTube is not a very good reference point for side effects to drugs. Every person experiences every drug differently. The people on YouTube acting "high" is, in all likelihood, an extreme example regardless of what drug they were given. People who act "normal" are usually not deemed YouTube worthy so they don't get their own videos. --Stabila711 (talk) 22:16, 25 August 2015 (UTC)

I completely agree that youtube is not a WP:RS, confirmation bias, selection bias, all that. But I am a bit surprised that NO was the only anesthetic you got. I still can't find any good description of what drugs are used and where, or even general trends. It seems from my limited research (skimming retrospective study like the ones I've linked) that there is a ton of variability, perhaps depending on decade, country, number of teeth extracted, hazards of the specific case etc. etc. SemanticMantis (talk) 22:42, 25 August 2015 (UTC)

Mine were not impacted and where relatively easy extractions. I didn't even need the pain medication they gave me afterwards. I guess my dentist didn't feel the need to go any further with the anesthetic since there were no expected problems. --Stabila711 (talk) 22:52, 25 August 2015 (UTC)

If a tooth is impacted, or the extraction is otherwise expected to be difficult, the patient may be treated with Pethidine (Demerol) rather than the type of anaesthetics used for other dental work (e.g. xylocaine). I had all four of mine extracted in the US, on Demerol. That's my only experience with opiods, and I didn't feel high at all - afterwards I had a warm pleasant all-over sensation, and I was cheery and talkative and (as far as I was concerned) perfectly lucid. But I suspect I may have babbled some. Your YouTube observation inevitably has a sampling bias (because no-one posts, shares, or views, videos of people who've had dental treatment and aren't funny or stoned). But there may also be a difference in dental norms in the US when compared to the UK - it may be the case that wisdom tooth extractions in the US are more likely to be done under an opiod in the US than in the UK. -- Finlay McWalterᚠTalk 21:50, 25 August 2015 (UTC)

Interesting (the connection to NO). I've read that balloons filled with NO gas used to be exploited as a recreational drug by the rave scene (and witnessed people inhale from said balloons, and laughing gas is a common topic/trope in movies etc...) But dentists here (Germany) have completely moved on to injections. Lidocaine makes you pretty high too, though.Rh73 (talk) 21:59, 25 August 2015 (UTC)

Yes, so-called hippy crack has been used by many people in non-medical contexts, long before the word "rave" was coined. But as I relate above, it was indeed used this century for dental procedures. Auditory hallucination is a very common side effect. I recall the sound of dentist drills sounding deeply beautiful whilst under the medical influence :) SemanticMantis (talk) 22:07, 25 August 2015 (UTC)

Yeah I always thought acting stoned was pretty rare after having wisdom teeth removed, but what I'm wondering is why this rare occurrence only happens in America. After watching a few videos and seeing they were all American I searched through dozens of videos and skipped each one with an American accent. Must've been through like 30. Didn't find any British/Irish/Australian/Kiwi. Dunno about Canadian. 2.102.185.43 (talk) 00:02, 26 August 2015 (UTC)

It might be a regional thing. Whatever I was given, I was just somewhat relaxed but fairly lucid while getting my teeth out (akin to lying back, closing your eyes, and listening to all of The Dark Side of the Moon on some good headphones while sober), but whatever they gave me for after made the following week a still-lucid hell. Ian.thomson (talk) 00:15, 26 August 2015 (UTC)

See confirmation bias. The use of sedatives during surgery is not necessarily unique to the U.S. Filming a person who is "coming out" of sedatives may be more prevalent in the U.S. due to various cultural differences between the U.S. and other countries. That is, a person who is regaining their faculties from sedatives after ANY surgery ANYWHERE in the world is going to have the same groggy, detached behavior. It's only Americans who feel the need to take a video of their friends in that state and post it on YouTube for the world to see. --Jayron32 18:10, 26 August 2015 (UTC)

Confirmation bias is surely a factor as I said above, but we have as yet no compelling evidence that the anesthetics commonly given in the USA are the same as the anesthetics commonly given e.g. in Europe. It could indeed be the case the patients in the USA tend to be given higher doses of drugs with more psychoactive effects, compared to other places in the world. And no, not EVERY patient of ANY surgery is going to have the SAME groggy, detached behavior. Some of them may outright hallucinate, some may have memory loss or euphoria, some may just go to sleep. The dose and type of sedative will surely play a role, even if people in the USA are more likely to post these vids on youtube. SemanticMantis (talk) 20:39, 26 August 2015 (UTC)

I wasn't making the point that the ANY particular conclusion was absolutely wrong. If anything, the entire discussion is stupid because we're extrapolating data from such a miniscule number of cases; that's the issue with biases, not that any one conclusion is better or not, but that all of the conclusions everyone is coming up with are completely fucking worthless because they're ALL just based on a few anecdotes and isolated cases. The OP starts with the premise "Americans are <insert negative stereotype here> because I saw some videos on YouTube. Prove me right, please." No, there's nothing to do to prove them right. The best we can do is to encourage the OP to stop jumping to ridiculous conclusions based on incomplete data, and leave it at that. Instead, we're all playing amateurs saying "No, Americans aren't <your negative stereotype>, they must be <this different negative stereotype> because I heard this other anecdote once/I had this personal experience once, etc." No. It's a unanswerable question, and we should stop humoring people who present such questions, and merely inform them why the entire premise behind the question is faulty. --Jayron32 02:31, 28 August 2015 (UTC)

It could be that dentists in the US aren't as regulated and as such great vary in what drugs they use. I think in most other English-speaking countries it's centrally controlled or regulated by the government, especially in the case with the NHS in the UK. 2.102.185.43 (talk) 02:23, 27 August 2015 (UTC)

That is a huge difference, yes. US dentists are regulated by some government laws, but they're otherwise completely independent.

As for confirmation bias, the US makes up ~64% of native English speakers, while the UK only makes up ~16%. Even if all other things were identical, that would mean that Americans would be four times more likely to upload a video of something that happened to them than Brits. Ian.thomson (talk) 02:42, 27 August 2015 (UTC)

In case anyone cares, I live in the U.S. and had three impacted wisdom teeth removed. I was given NO, but also the typical local anesthetic injection. While under the gas, everything was kind of slowed down and distorted. If you had been able to talk to me I would probably have been a little loopy, but of course that would have been a little difficult with two peoples' hands in my mouth. Once the gas was stopped the effects wore off pretty quickly. As others have noted, individual reactions might vary, but based on my layman's knowledge I suspect many of the people in the videos were given either benzodiazepines or opioids. These tend to have stronger and longer-lasting psychoactive effects, especially in people not habituated to them. As also discussed above, these drugs are sometimes used for complex procedures as well as in sedation dentistry, which is used for some people who are severely distressed by dental procedures or have other issues. Now, it might have been nice if I had some of those drugs after my extractions. All I got was co-codamol, which had no effect at all that I could tell, so I spent the next week guzzling ibuprofen with an aching jaw. --71.119.131.184 (talk) 05:48, 27 August 2015 (UTC)