Wikipedia:Reference desk/Archives/Science/2017 February 4

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February 4

Stephen Hawking's illness

The progress (or regress, I suppose) of the disease of typical ALS patients is well documented, so a neurologist can give a general prediction of how long a patient will live if something else doesn't kill him first. However, Stephen Hawking isn't a typical patient, considering that he's had the disease for more than half a century. Have there been any publicly announced predictions of his remaining lifespan in recent years (you get to define "recent") by reputable neurologists? All I'm finding on Google is numerous hoaxes claiming that he's already died and been replaced by some poor sap who's had to become a body double. Nyttend (talk) 05:04, 4 February 2017 (UTC)

Related question—have they studied him to determine why he's been able to live so long, with the hope of applying that knowledge to other patients? If so, what have they learned?Loraof (talk) 17:14, 4 February 2017 (UTC)

Life expectancy for ALS is in general much shorter, but his is a rare form of ALS.

From the relevant article: "Hawking has a rare early-onset, slow-progressing form of amyotrophic lateral sclerosis (ALS), commonly known as motor neurone disease in the UK, that has gradually paralysed him over the decades. He now communicates using a single cheek muscle attached to a speech-generating device."

Life expectancy can also be prolonged through better supportive care like assisted breathing machines.

--Llaanngg (talk) 01:11, 5 February 2017 (UTC)

Given the nature of his condition it seems to me that his life is most at risk from secondary effects e.g. if he gets pneumonia. Count Iblis (talk) 22:05, 5 February 2017 (UTC)

Reverse osmosis

Can water purified by reverse osmosis be considered sterile insofar as common pathogens are effectively removed? Roger (Dodger67) (talk) 05:33, 4 February 2017 (UTC)

Only if all the downstream equipment has also been effectively sterilized prior to startup. 2601:646:8E01:7E0B:8C41:94D2:B8B0:3710 (talk) 06:15, 4 February 2017 (UTC)

Drinking water in bottles, which was taken from "unselected source", filtered with reverse osmosis, I found declared to be processed with "ozone and uv light". --Hans Haase (有问题吗) 17:04, 4 February 2017 (UTC)

How small are RO membrane pores compared to bacteria or virusses? Roger (Dodger67) (talk) 19:28, 4 February 2017 (UTC)

Since they have to filter out the dissolved salts, they by definition have to be smaller than viruses. 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 09:35, 5 February 2017 (UTC)

Spectrophotometry

In UV-vis spectrophotometry, which wavelengths are the best for detection of aqueous Cu²⁺, Al³⁺/AlOH²⁺/Al(OH)₂⁺, and PO₄³⁺/HPO₄²⁺/H₂PO₄⁺? 2601:646:8E01:7E0B:8C41:94D2:B8B0:3710 (talk) 06:22, 4 February 2017 (UTC)

Anyone? 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 03:24, 8 February 2017 (UTC)

Wastewater disposal

Can anyone refer me to the current regulations for disposal of dilute, acidic aqueous waste containing (low levels of) phosphate, copper and aluminum ions? 2601:646:8E01:7E0B:8C41:94D2:B8B0:3710 (talk) 06:25, 4 February 2017 (UTC)

Identifying the correct regulations might be considered legal advice, which we aren't allowed to give. Even if it isn't, it's certainly impossible without knowing what jurisdiction's regulations you're talking about. --76.71.6.254 (talk) 07:49, 4 February 2017 (UTC)

Looking up the IP the location is as I suspected in the US, so if you just wait a while there will be no regulations on whatever waste you dispose of [1]. Dmcq (talk) 08:41, 4 February 2017 (UTC)

Any source for that claim besides notorious fake-news outlets like Vox? 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 09:36, 5 February 2017 (UTC)

Yes it is an exaggerated headline but it is essentially true, see [2], [3]. No direct help for you but it shows the way the balance on environmental protection is going. Dmcq (talk) 08:55, 8 February 2017 (UTC)

The answer is highly dependent on where you are located, who is generating the waste and how much you are generating. Assuming you are in the US you will be subject to Federal, state and potentially county laws. If you are an individual you are generally exempt from many regulations and your best bet would be to take your waste to a household hazardous waste disposal facility. If you are generating waste on behalf of a corporation or University you will need to comply with regulations such as getting an EPA ID, and paying fees to register as a hazardous materials generator Generator classes. If a hazardous waste generator such as a CESQG (see link) wishes to treat waste it becomes even more complex because you may need to submit information on exactly how you are treating the waste and provide proof that it has been rendered safe because you are now you are running a hazardous waste treatment facility. — Preceding unsigned comment added by 204.28.125.102 (talk) 01:02, 7 February 2017 (UTC)

Thanks! 2601:646:8E01:7E0B:CFC:95E:6BD7:D508 (talk) 02:37, 7 February 2017 (UTC)

Celestial body and person related to the following image

Which person and celestial body is related to the following image? Figure out the celestial body
Try to extrapolate the name of a celestial body from the images, that will lead to something that person was known for. Oh, and by the way, what's that myth about cats? Try to get a number from the first and second image (myth) to get the celestial body's name. Join that name with something related to the first image to get the thing for which the person is known. I don't know the answer, please, help. 103.253.146.245 (talk) 08:51, 4 February 2017 (UTC)

Everything there is a mammal, so the connection might be milk, with the Milky Way (or Galaxy). Graeme Bartlett (talk) 11:40, 4 February 2017 (UTC)

Just a thought: Gemini (twins) and Leo (lion, well OK so it's a cat but still) --TammyMoet (talk) 15:56, 4 February 2017 (UTC)

Leo Minor Sagittarian Milky Way (talk) 17:14, 5 February 2017 (UTC)

You might have better luck on puzzling.stackexchange.com —Tamfang (talk) 08:39, 6 February 2017 (UTC)

Why aren't opiods commonly used as suicide drugs?

In as much as I understand it, opiods typically kill (relatively) quickly by causing respiratory failure. As analgesics, I guessed that an opiod overdose would be almost painless. I'm aware that this is slightly facile: paracetamol overdose is often painful; however, paracetamol death usually occurs quite a long time after consumption when most, if not all, the analgesic effect has worn off; further, paracetamol is not known as a particularly potent analgesic.

Yet my (albeit limited) research suggests that few suicide attempts use opiods. Why not?--Leon (talk) 14:04, 4 February 2017 (UTC)

I think it is mainly an issue of availability. Opioids are all prescription drugs, and prescriptions are only supposed to be given to people who are experiencing severe pain. They aren't as a practical matter all that hard to obtain, but hard enough to reduce their use for suicide. A secondary factor is that opioids are very potent at reducing emotional distress, so a person who is able to get them might use them as a substitute for suicide. Looie496 (talk) 14:35, 4 February 2017 (UTC)

They are. They're used for analgesia in late-stage terminal conditions and, as such, it's easy to arrange an overdose that is indistinguishable from the increasing palliative dose. The most famous case is probably King George V. Andy Dingley (talk) 16:05, 4 February 2017 (UTC)

Okay, then why does the lethal injection used in the United States not use opioids? I've heard that the present procedure may be painful.--Leon (talk) 18:28, 4 February 2017 (UTC)

Most legal experts on capital punishment in the United States hold the position that for a drug or pharmaceutical to be legal for use, it must be specifically tested and regulated for a specific clinical purpose - namely, for the purpose of causing death. Few, if any, regulators and drug providers want to formally pursue the costly and emotionally-fraught steps to clinically test a fatal drug to the point where it can pass regulatory muster. It is not, in the eyes of legal scholars, sufficient to use a clinical drug that is known to be fatal in an off-label use.

Capital punishment in American law is very complicated; elements of the decision-making process are not motivated solely by scientific facts or ideologies. In other words - even if we all know that a drug can make a person die, and even if a plurality of scientists know (or believe they know) of a method to make the death painless, that does not in itself pass the muster needed to make the drug acceptable for use in cases of capital punishment.

It is primarily for this reason that there is so much debate about exactly which pharmaceuticals may be used to conduct a lethal injection: the fundamental law in our nation (the United States Constitution) mandates that the punishment must be neither "cruel" nor "unusual." Analysis of constitutional law is a matter that frequently defies a scientific world-view.

For example: in 2007, the United States Supreme Court was presented with the simple question, "Do the means for carrying out an execution cause an unnecessary risk of pain and suffering in violation of the Eighth Amendment upon a showing that readily available alternatives that pose less risk of pain and suffering could be used?"

In answer, the response was: "THE MOTION OF PETITIONERS FOR LEAVE TO PROCEED IN FORMA PAUPERIS IS GRANTED." Decipher that, you poor, brilliant scientific ethicists! Here is a brief summary, from Cornell University, to help the rest of us make sense of the decision.

Nimur (talk) 18:56, 4 February 2017 (UTC)

Opioids (note spelling) certainly can cause death, and are frequently used for (essentially) euthanasia. I have watched more than one family member in dire straits taken off to the hospice; people there die remarkably quickly while under the influence of large quantities of opioids... I think the staff have become exceedingly efficient at it. But I do not mean to blame them as they generally become involved at the stage where there is no right answer. Wnt (talk) 02:26, 5 February 2017 (UTC)

When a fly falls into water then it dies?

When a fly falls into water, then it can't move because of Van der Waals force? After how long does it die? I'm asking it because I saw on youtube a video about "miracle" in which a 'dead fly' was taken out of water when it dies and some people put on it ash and then it was revived. I don't believe it and that's why I'm looking for the scientific explanation behind it.93.126.88.30 (talk) 18:30, 4 February 2017 (UTC)

Flies are an insect and require oxygen to live. See Respiratory system of insects - Insects do not have lungs, rather, they have a series of tubes called spiracles which start as openings on the body surface and them permeate the animal's deeper tissues. I suspect that when a fly lands in water, the water blocks air (containing oxygen) moving into the spiracle system and eventually kills the fly. As for how long this takes, that would depend on many factors such as the size of the fly, how healthy the fly was when it landed, and how much it struggles (which would use up oxygen more quickly. DrChrissy ^(talk) 19:06, 4 February 2017 (UTC)

I have just watched the YouTube video. The first thing I would like to say is that I find messing around with animals in this way is morally distasteful to say the least. Back to the science. Once removed, the fly might very probably have recovered with no further action. The cigarette ash might have acted in several ways. First, the warmth of the ash might have increased the metabolism of the fly which is an ectotherm. Increased metabolism would have allowed the fly to move more normally. Second, the ash might have absorbed the water from the spiracles and their openings, thereby allowing the fly to "breath" normally and recover, DrChrissy ^(talk) 19:15, 4 February 2017 (UTC)

Thank you. What about the Van der Waals force here? 93.126.88.30 (talk) 19:20, 4 February 2017 (UTC)

This is my 2 ¢ worth. Watch a flying insect trying to exit a glass window. It has a simple brain that keep trying to fly through the glass pane until it it utterly exhausted and finally sits on the sill - no longer able to move a muscle. Looks dead, one can pick it up without it giving any response. After a period of rest however, it become active again and tries to fly through the pane once more. Think, that this fly upon finding itself in a liquid some 850 time more dense than air, s/he or it just became exhausted. The ash may have soaked up the water but remember... Next: Van der Waals force. Most flying insects have either a hydrophobic outer skin or exoskeleton which repels water (otherwise they would drown when it rains). This is why soft-soap is such an effective insecticide against infestations like greenfly. Being a wetting agent it prevents spiracle respiration. Also, soft soap is made with potassium hydroxide and thus serves as plant food. Me thinks, this fly in the video just had the time to recover after being fished out. --Aspro (talk) 23:36, 4 February 2017 (UTC)

Thank you. I'm not sure I got the answer about the "Van der Waals force". In this case of the landing of the fly to the water, did "Van der Waals force" is the causer for it to be not able to go out? You've said that insects hydrophobic bodies (I thought they have just hydrophobic 'legs' but the body is not) then, what is the reason for them to not be able to get out of the water in case of landing there?93.126.88.30 (talk) 09:40, 5 February 2017 (UTC)

When you put an insect in water and limit its respiration, it can reduce its activity to survive longer. Being cold-blooded it requires very little metabolism under adverse circumstances. Since some air diffuses through the water into any air space near the insect, it is even possible that they could survive quite long periods this way, though I don't know. Putting it in cold water helps much more - you can anaesthetize insects for days in cold temperatures, then warm them up and they are as they were. The ash simply mechanically takes up some of the water, and has no other positive effect (nicotine has a very negative effect on insects, but I suppose there is little left in ash). Now as for "Van der Waals force", this is simply a matter of it being "wet", a macroscopic everyday concept we readily understand. The water adheres to the insect by dispersive forces, perhaps also by some hydrogen bonds in places.

As for the "morality" of messing with insects, I find the complaint utterly ridiculous and without any philosophical validity. Every day we consume foods that rely on our payment of farmers to spray vast areas with insecticides (the environmentalist fringe might insist on organic insecticides). There is not a Jainist here, I would guess. So why should people hesitate to torment insects by ones and twos for intellectual curiosity when they torment them by countless thousands for some extra tasty morsels and food that sometimes gets thrown away? Is curiosity so disreputable? This is characteristic of all "animal rights" crusades - as a movement they are governed by appearances, by willful ignorance, by shaking down those vulnerable to racketeering, above all by coordinated bullying of whosoever acts differently than most people. They will walk past a thousand mousetraps in the supermarkets without comment but burn down a lab building because someone wants to cure cancer in a mouse model. Wnt (talk) 02:21, 5 February 2017 (UTC)

@Wnt:Please choose your words very carefully - are you suggesting I am on an "animal rights crusade"? DrChrissy ^(talk) 17:50, 5 February 2017 (UTC)

@DrChrissy: No. But even a mild sentiment favoring a certain philosophy can be evaluated in terms of where those who believe in it intensely have gone with it. Wnt (talk) 19:47, 5 February 2017 (UTC)

@Wnt: The fact that you started your reply with "No. But..." is extremely disingenuous and leads readers to confirm you are accusing me of being on an "animal rights crusade". If you are prepared to conclusively withdraw from this casting of aspersions, I will explain my position and why I made the comment I did - you might learn something from such an interaction. DrChrissy ^(talk) 20:06, 5 February 2017 (UTC)

At this point I have no idea what you mean. I know that I have no concern for the morality of tormenting a fly, and AFAICT you disagree with that position. In my mind, it is synonymous to think that messing with a certain animal is immoral, and to believe that the animal has a "right" not to be messed with. Wnt (talk) 20:19, 5 February 2017 (UTC)

And therein lies the problem - the two are not synonymous. DrChrissy ^(talk) 20:28, 5 February 2017 (UTC)

One doesn’t have to be a 'Jain' nor an animal liberationist to hear that small-quiet-voice inside that says lesser creatures are not our playthings. As a child, I was guilty of this before I could hear that voice. I put tadpoles under my microscope to see the blood corpuscles coursing through their tails. Now I feel bad about it, but not in a sentimental way. Rather it is is the awaking of moral awareness and mindful intentions that advances science. It is only through respecting our subjects under study that we can gain better knowledge. To suggest that mindless experimentation is OK is to keep to a child-like position.--Aspro (talk) 21:28, 5 February 2017 (UTC)

Very well said. When I was a child, I stamped on ladybirds when there was a plague of them one year. Why? - because I could. But we live and learn. “The greatness of a nation and its moral progress can be judged by the way its animals are treated.” ― Mahatma Gandhi. DrChrissy ^(talk) 21:46, 5 February 2017 (UTC)

A child feels bad about watching a tadpole suffer out of water; an adult repaves a back road riddled with mud puddles and does not give the thousands of tadpoles in them a second thought. To me the premise seems to be that an act is only immoral if you think about it, and since the curious (and children) are at risk of thinking, they are exceptionally wicked. I think that is a notion that animal rights supporters generally tend to hold... though they never thought about it. Wnt (talk) 14:19, 6 February 2017 (UTC)

@Wnt: Have you ever considered that people might have moral convictions towards animals, or follow a set of moral and ethical guidelines in animal experimentation that do not involve them being an "animal rights supporter"? DrChrissy ^(talk) 16:33, 6 February 2017 (UTC)

@Wnt: “premise seems to be that an act is only immoral if you think about it” . Homo sapiens means "wise man". Requires both thought and introspection etc. Some primates (including some humans) achieve this full ability and some don't. Normal distribution explains there is a spread of abilities. So, some Homo sapien individuals, are happier remaining ignorant, rather than employ their cognitive powers. So, don't think its is strange that some editors still hold this view point. --Aspro (talk) 17:53, 6 February 2017 (UTC)

Thank you. I'm not sure I got the answer about the "Van der Waals force". In this case of the landing of the fly to the water, did "Van der Waals force" is the causer for it to be not able to go out? (simply I didn't understand the meaning of the sentence "The water adheres to the insect by dispersive forces, perhaps also by some hydrogen bonds in places.") 93.126.88.30 (talk) 09:40, 5 February 2017 (UTC)

Coming back to DrChrissy's point about heat and ectotherms. The video is in Hebrew and it can get hot where this photos was taken. So people often drink chilled water. Looked it up. If most flying insects are cooled below 8 ° C they become immobile (not dead). So the fly may have just warmed back up and become active again.--Aspro (talk) 15:50, 5 February 2017 (UTC)

Van der Waals force is uninformative when used loosely as a synonym for the totality of intermolecular forces. This case concerns the wettability of a fly in water. Insects have hydrophobic surfaces characterized by greater than 90° contact angle to a water surface. Other examples of hydrophobic surfaces are the self-cleaning Lotus effect of some flowers and insect wings, and the water-walking feat of the "Jesus lizard" Basiliscus. The fly in the video does not appear ever to have sunk into the water (which could have been made fatal by adding a Detergent) and the moral objections raised against the revival experiment echo those against Nazi human experimentation at the Nuremberg Doctors' trial. Defense argument that such experiments were the only way to develop recovery treatment for e.g. downed pilots was rejected by the Tribunal. Blooteuth (talk) 16:24, 5 February 2017 (UTC)

@Blooteuth: The Van der Waals force is a combination of dipole-dipole interactions, dipole-induced dipole interactions, and mutually induced dipole interactions (London force), but not hydrogen bonding. But hydrogen bonding is rather important where hydrophilicity is concerned. I would expect the effect of detergent to be as a surfactant which enhances the wettability of small structures, such as insect tracheae, reducing the air internally available and making it much more difficult to purge the water if drying it out with ash or some other absorbent material. But I don't actually know that. Wnt (talk) 19:56, 5 February 2017 (UTC)

@Wnt: A purpose of our responses is to provide Wikipedia references for further study. The link to Van der Waals force that I provided explains what they are. The very first sentence of the link to Detergent that I also provided states "A detergent is a surfactant or a mixture of surfactants...". DrChrissy already linked to Respiratory system of insects that describes their trachae but no page exists with the name "insect tracheae". Apart the link you added (why?) to London dispersion force I can't see how your post is helpful to me(?) or to the OP. Blooteuth (talk) 00:01, 6 February 2017 (UTC)

Well, hydrogen bonding contributes to wettability but is not a Van der Waals force. Wnt (talk) 14:19, 6 February 2017 (UTC)

Not sure ash has anything to do with the recovery. I've seen flies "come back to life" after merely drying out. Of course, they weren't really dead, they simply go inactive when they deplete their oxygen supply. Just how inactive they go would be an interesting study. Do all nerve impulses stop, or merely slow down ? StuRat (talk) 16:48, 5 February 2017 (UTC)

And I am still a little bit confused about the reason that the insect stuck to the water without any ability to get out of it. In the meantime, I got here the explanation that they're cold blood and under 8° C they become immobile, then if it's the case here then it explains why the insect was stuck in the water without moving. But if I'm not mistaken I saw in the past insects that landed to liquids - includes water in the room temperature and they moved in the water by shaking their bodies back and forth but they couldn't really get out of the water and it looked like they are linked to the liquid, and that's why I thought on Van Der Wals force.93.126.88.30 (talk) 22:56, 5 February 2017 (UTC)

You are talking about many variables here. It is possible/probable that the fly would not have been able to take off directly from the water due to the forces discussed above. However, if the fly had moved around on the water surface until it bumped into the side of the glass, it would have climbed up the side of the glass, probably stayed there until it dried a little and then flown off. Do you have evidence that the water in the glass was 8° C? Signing 24 hrs later - DrChrissy ^(talk) 17:06, 7 February 2017 (UTC)

Don't have a good RS for you because my text books are all up in the attic now (am retired). But a 20 second google (which you could have done) came up with this : They are most active during the day at temperatures of 80 to 90°F and become inactive at night and at temperatures below 45°F. . Which is 7.222 degrees Celsius. Approx 8 ° C. In hot countries, water is often served up straight from the cooler at near 0 degrees Celsius. Which you can also experience too if you go on vacation or work in such places. --Aspro (talk) 23:33, 6 February 2017 (UTC)

I have been to many countries where water is available from coolers - including working for 12 years in Australia. I have to say that your stressing of "But a 20 second google (which you could have done) came up with this" is rather unwelcome. My question about the RS was directed at the IP to encourage them to go and do their own research, and I think your comment should have been directed at the same editor, not me. DrChrissy ^(talk) 00:45, 7 February 2017 (UTC)

Crossed wires? I first bought up the point about 8 ° C and was giving a generic reply to that post. If you had signed your post I would have made sure that I indented my reply after s/he. Whilst I am assured by my closest fiends friends that I am just a raving psychotic I am not in the same breath psychic (unlike my cat).--Aspro (talk) 01:33, 7 February 2017 (UTC)

Yikes - my fault for causing the crossed wires by not signing my post - apologies for that.As for psychic cats, I have 2 of them. Being rather cold in the UK at the moment, I am trying to keep heat in by closing room doors. What makes a cat immediately want to go through a closed door when it had been open 60 seconds previously! DrChrissy ^(talk) 17:06, 7 February 2017 (UTC)

Might be that all three of you are on a different time schedule and culture. You might come in and want to settle down in front of the TV and cat thinks “Oh no not this again” and want to wonder off to a different part of the house (that could be the trigger for wanting to leave so soon as you have -in your estimation - closed the door). My cat can't abide the TV serial EastEnders … may be because the characters are always 'arguing' with each other and they find the tone and intonation of voice distressful. Note: not saying they understand the dialogue but rather they aware from tone and intonation when you are unhappy at something they did to your displeasure. Do your two cats always do-thing-together or are they living independent lives under that same roof? They don't recognise an 'alpha' male as leader of their pack so don't want nor be inclined (as to their nature) to be at the homeowners heal 24/7. Wondering if its time for all door manufactures to fit cat flaps in as standard -even for internal doors- or place door handles a lot lower down. Fitted at the time of manufacture it would not cost a lot more and save one from continually getting up to let cat in or out. Just a thought. --Aspro (talk) 14:08, 8 February 2017 (UTC)

Temperature of reflecting material

If we change the temperature of any body, would it change how it reflects light? I assume they would emit different amounts of heat but would they reflect light differently too?--Llaanngg (talk) 19:07, 4 February 2017 (UTC)

The most standard simple models of electromagnetic wave reflection - such as the reflection coefficient or the Fresnel equations - are not parameterized by temperature. Surely, we can extend these models to account for the actual, non-simple effects that apply to any specific real scenario; but such an extension to the model would not be universally or generally accurate. In practice, it is more likely that we would use an empirically-derived model, rather than attempting to model the effect of temperature on optical reflectivity using first principles of physics.

One of my go-to books on optics, Meyer-Arendt, Introduction to Classical and Modern Optics, contains entire chapters devoted to discussing reflectivity; but "temperature" is never mentioned. Loads of other parameters are described - angle of incidence, index of refraction, and (...I mean, this book is really thorough!) even esoteric optical effects like metallic extinction. But temperature is never mentioned and isn't even in the book's index. Clearly, experts in the field of optical physics do not consider temperature to be a primary factor for most classical and modern models of optical reflectivity.

Nimur (talk) 19:19, 4 February 2017 (UTC)

For the interested readers who want to learn more about extinction, we have articles on minerological extinction, but none on metallic extinction! Once again, we reference-desk regulars have located, and then crossed, the exact boundary of all the human knowledge that is documented on the internet! Nimur (talk) 19:32, 4 February 2017 (UTC)

Some materials are thermochromic and change colour when heated or cooled. In the infrared spectrum there can be significant changes dependent on temperature, but this is also where you get the black body radiation. Graeme Bartlett (talk) 22:40, 4 February 2017 (UTC)

In some cases high temperature will cause a surface to oxidize or boil away, degrading that nice shiny surface. And of course if a material is glowing white hot it may be difficult to measure how reflective it is; as a practical matter mirrors should be cool enough so that they don't swamp any reflected light with self-generated light. --Guy Macon (talk) 23:39, 4 February 2017 (UTC)

@Guy Macon: A reflective material shouldn't glow white hot, AFAIK - it should reflect that light internally, so to speak, and function as poorly as a blackbody as it functions well as a mirror. Wnt (talk) 19:59, 5 February 2017 (UTC)

(Slaps forehead.) Of course you are right. It could still glow, but only if the mirror is imperfect. A perfect mirror wouldn't glow at all.

Then again, in some cases the light you want to reflect is in the far infrared. As https://jwst.nasa.gov/mirrors.html says, "One further challenge is to keep Webb's mirror cold. To see the first stars and galaxies in the early Universe, astronomers have to observe the infrared light given off by them, and use a telescope and instruments optimized for this light. Because warm objects give off infrared light, or heat, if Webb's mirror was the same temperature as the Hubble Space Telescope's, the faint infrared light from distant galaxies would be lost in the infrared glow of the mirror. Thus, Webb needs to be very cold ("cryogenic"), with its mirrors at around -220 degrees C (-364 degree F).".

I would like to be able to say that I am smart enough to have been thinking of far infrared, but the truth is that I simply had a brain fart and didn't consider the fact (which of course I knew) that good mirrors are bad emitters, and vice versa (thus the phrase "black body radiation -- a black body is the opposite of a good mirror). Thanks for correcting me. --Guy Macon (talk) 03:57, 6 February 2017 (UTC)

That's a great example of why your original point really is relevant. The risk of reflected light being "swamped" depends on both the strength of the reflected light and the imperfection of the mirror. If a mirror is 99% reflective (I assume Webb's is much better) it does a great job of delivering the light ... yet if that light is less than 1% of the blackbody emission, it still gets swamped out. Wnt (talk) 14:29, 6 February 2017 (UTC)

stalled replicating DNA

joke about a roommate
The following discussion has been closed. Please do not modify it.
The following discussion is closed. Please do not modify it. Subsequent comments should be made in a new section. Joke has been made, no need to discuss this i am not a student or writing a paper but i do have a serious issue i need help with. i have a stalled DNA fork replication front in and at my residence. i dont know how or where to get the help that i need. --Stuckinweirdzone (talk) 23:58, 4 February 2017 (UTC) Unhatting: this might be a question. There is a thing like a stalled DNA replication fork. --Llaanngg (talk) 02:42, 5 February 2017 (UTC) If you can explain the question, or answer it, by all means do so. I can make no sense out of it. Wnt (talk) 02:55, 5 February 2017 (UTC) It's simply a lame attempt at (nerdy) humor. It should be rehatted or removed. General Ization Talk 02:57, 5 February 2017 (UTC) The above discussion is closed. Please do not modify it. Subsequent comments should be made in a new section.