Wikipedia:Reference desk/Archives/Science/2021 May 9

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May 9

Vacuum activity in humans

The article on displacement activity mentions humans have them and gives examples. The article on vacuum activity does not mentions humans. Do humans have vacuum activities? Examples? --Error (talk) 00:58, 9 May 2021 (UTC)

Watching cat videos on YouTube? Many people cannot sit still for an extended time; they get up every know and then and walk a few steps before sitting down again. Others may call them "restless". (The behaviour may be advantageous to the organism, but is not elicited by a stimulus.) But is this an "innate fixed action pattern" (FAP)? As far as I am aware, no FAPs have been reported for the genus Homo, and to be classified a "vacuum activity", the behaviour must be that of an FAP.  --Lambiam 10:14, 9 May 2021 (UTC)

I can barely sit still for 15 minutes without fapping. Honestly, I could be watching TV and the adverts come on and it's fap fap fap. Thank God for smartphones. Those little screens are a real boon for frequent fappers like me. nagualdesign 20:54, 9 May 2021 (UTC)

Wiktionary: fap (verb).  --Lambiam 08:27, 10 May 2021 (UTC)

Witionary: joke. --Jayron32 16:24, 10 May 2021 (UTC)

Not to be confused with frapping. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:44, 10 May 2021 (UTC)

• See also fidgeting. --184.147.181.129 (talk) 05:40, 10 May 2021 (UTC)

How can we see light of UV lamp ?

UV is not in our range of visible spectrum. But How can we see light of UV lamp ? Rizosome (talk) 14:46, 9 May 2021 (UTC)

Most consumer-level UV lamps also emit in the visible range. DMacks (talk) 15:43, 9 May 2021 (UTC)

See blacklight. Essentially, most "UV lamps" are light sources that are not monochromatic, and therefore they emit light over a range of wavelengths. In the case of black lights, even if most of the light is in the UV, some is in the visible. A mercury vapor fluorescent tube black light, for example, while blocking most visible light from the mercury emission, fails to block the 404 nm, giving the violet glow appearance. I imagine this is somewhat intentional, since the UV given by these lights is not that great for unprotected human eyes, and by having the purple glow, you know when the lamp is on or off. Not that traditional fluorescent tubes, the ones commonly used to every day room light, are also mercury vapor lamps. The reason they put out visible light and not UV light is because the glass tubes have been intentionally made to block UV and allow visible, otherwise they too would emit UV light. This is actually not that hard to do; glass in general is poor at transmitting UV light and you need specially made glass to pass UV, such as Wood's glass (which is great at letting UV and IR, but blocks most visible, so good for black lights), or quartz glass, which is commonly used for optics and cuvettes in spectroscopy as it transmits UV light much more efficiently than traditional glass, but also works well with visible light. When I need to determine protein concentrations in samples lacking a chromophore, I will commonly use quartz cuvettes and measure in the ultraviolet, making use of the UV absorption of aromatic amino acids. Back to black lights, as I said, in general, these light sources are not monochromatic, and so emit light that isn't just UV. The exception to this would be lasers, but UV lasers are not very common. --OuroborosCobra (talk) 16:56, 9 May 2021 (UTC)

@DMacks: I am asking how can we see it? Rizosome (talk) 17:59, 9 May 2021 (UTC)

We have answered you. What part of the answer did you not understand? Honestly, this is getting very tiresome, as you seem to not read any of our answers to you. --OuroborosCobra (talk) 18:01, 9 May 2021 (UTC)

@OuroborosCobra: I find it too technical your edit is. Rizosome (talk) 18:13, 9 May 2021 (UTC)

DMacks answer was not the least bit technical. What part of it did you not understand, since you directly referenced them? Frankly, I'm not buying it, as you've been given simple answers before and still ignore them. Black lights do not emit just UV light. They are not monochromatic light sources. A fluorescent tube black light, for example, also emits visible 404 nm violet light. Please tell me what part of this statement you do not understand. --OuroborosCobra (talk) 18:19, 9 May 2021 (UTC)

@OuroborosCobra: I am not asking about black lights, my question related to UV lamp only. Rizosome (talk) 20:19, 9 May 2021 (UTC)

@Rizosome:, "black light" is a colloquial name for the UV lamps that you can visibly see a purple color, but fine, I'll reword this so you hopefully understand it. UV lamps, if you can see them, do not emit just UV light. They are not monochromatic light sources. A fluorescent tube UV lamp, for example, in addition to UV light, also emits visible 404 nm violet light. Please tell me what part of this statement you do not understand. --OuroborosCobra (talk) 20:24, 9 May 2021 (UTC)

@OuroborosCobra:So we are seeing 404 nm violet light when UV lamp works? Rizosome (talk) 21:46, 9 May 2021 (UTC)

@Rizosome: If you are talking about seeing the bulb of a UV light. Short answer is yes. Longer answer visible light is from around 400 nm to 700nm. If you read the article on blacklight you will see that most of their spectrum is below 400nm but there is a secondary peak at 404 nm from mercury. If you are talking about when you hold the light over an object in the dark and then you can see it, then read the article on fluorescence. Dja1979 (talk) 03:53, 10 May 2021 (UTC)

@Dja1979:, your answer is likely too technical for @Rizosome:, who does not understand that there is no singular thing called a "UV lamp," and that blacklights are a type of UV lamp. --OuroborosCobra (talk) 14:25, 10 May 2021 (UTC)

@OuroborosCobra: I think mercury emission is one the reason behind 404 nm violet light. Rizosome (talk) 15:46, 10 May 2021 (UTC)

@Rizosome: yes, that's what we answered for you in about 3 different ways. Mercury emission is also the reason behind all of the UV light in said lamp. --OuroborosCobra (talk) 16:07, 10 May 2021 (UTC)

Be aware of the dangers.[1]. I was aware that mercury lights cause blindness but I didn't know why. 95.148.229.85 (talk) 19:01, 10 May 2021 (UTC)