Wikipedia:Reference desk/Archives/Science/2015 February 8

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

February 8

Telomeres predict maximum age of 200 years?

Is this right? I heard that people are born with 10,000 base pairs of telomeres and that people lose 50 base pairs of telomeres per year, so I divided 10,000 by 50 and got an estimated maximum human lifespan of 200 years. Is my estimation of a maximum human lifespan of 200 years correct and if not, can someone correct my calculation? Icemerang (talk) 09:08, 8 February 2015 (UTC)

I am extremely skeptical of neat round numbers like "10,000" and "50 per year". At best they are likely to be broad approximations. There are trillions of cells in the human body, each with their own telomeres. Some cells, such as neurons in the brain, rarely if ever divide once one reaches adulthood, so their telomeres will experience very little shortening. Numerous cell types that divide frequently, such as hematopoietic stem cells, express telomerase, meaning they can regenerate their telomeres. Really, telomere shortening is less important than it's made out to be in many pop science explanations of aging; it's primarily a defense mechanism against cancer. While it does play some role in aging, there are many other factors involved. --71.104.75.148 (talk) 13:57, 8 February 2015 (UTC)

And who says that you can live until your last telomere is gone ? A better way to estimate maximum human lifespan is to measure the lifespans of the oldest people. Based on that, it seems closer to 130 years. Of course, this requires that they have the best possible genes, diet and exercise level, so most people can't live anywhere near that long. StuRat (talk) 16:07, 9 February 2015 (UTC)

The "10000 / 50" estimate is a ballpark estimate, at best, as it makes too many gross oversimplifications. First and foremost, as already mentioned, some cells are constantly replaced throughout life, and some cells only divide during fetal development and early childhood. For example, White blood cells - cells of the adaptive immune system - are produced continuously throughout life, while neurons of the brain and the spinal cord are largely preserved (do not divide and are not replaced) for most of the human life span. A cyborg with a human nervous system (or parts thereof) and artificial body could potentially live much longer than 200 years according to your estimate. By contrast, by the age of 100 the immune system capability to produce new cells is nearly depleted, so it is mostly up to chance and modern medicine to keep the person from potentially fatal infections. Dr Dima (talk) 17:57, 9 February 2015 (UTC)

hypeto-particle

I saw the viral video of the hypeto-particle yesterday. It was dicovered on the third of feb. Can someone explain to me what it is and how can it lead to timetravel as early as 2016. — Preceding unsigned comment added by 105.226.98.192 (talk) 12:51, 8 February 2015 (UTC)

Wasn't it all hype to confuse you? I wasn't expecting it to be discovered until April 1st. Dbfirs 13:24, 8 February 2015 (UTC)

This thread is the only Google hit for "hypeto-particle". -- BenRG (talk) 00:10, 9 February 2015 (UTC)

• I think he meant "hypothetical" and there are Feb. 3 news hits for this January 27 publication: [1] Wnt (talk) 01:15, 9 February 2015 (UTC)

An interesting article, but lots of hypothetical particles have been suggested (see Supersymmetry for some other examples). This particular suggestion for a dark matter χ particle can be detected by 140 nm particles held in a vacuum in a 120 kHz harmonic trap provided by a tight laser focus and feedback ‘cooled’ to reduce the uncertainty in both their position (<1 nm) and velocity (500 µm/s), and this has to be done outside the atmosphere, preferably at a Lagrange point. If they have been detected, then someone has been very quick off the mark. And what's the connection with time travel? I still think it's all hype. Dbfirs 08:10, 9 February 2015 (UTC)

H2O2 cerumen reaction

Hydrogen peroxide - urea, or just hydrogen peroxide, is a common treatment for hardened ear wax. Users of H2O2 ear drops are familiar with the fizzing noise this treatment sometimes features, which is presumably due to the generation of a gas as a by-product of the reaction. As H2O2 is often used as an oxidiser, presumably this is some kind of oxidation reaction. But what specifically is the chemical reaction that takes place in this circumstance (and what is the gas - I'm guessing CO or CO2)? Is it lipid peroxidation? 46.208.67.136 (talk) 19:51, 8 February 2015 (UTC)

H₂O₂ gradually decomposes to produce gaseous oxygen and water. Many biological (and some non-biological) materials catalyze that process, and that's what's happening in this context. The gas production simply physically loosens the ear wax for easier removal.[2] DMacks (talk) 20:40, 8 February 2015 (UTC)

Urea? No one ever pissed in my ear when I was on the swim team. Is this an actual thing? μηδείς (talk) 22:02, 8 February 2015 (UTC)

I don't know if pissing in your swim teammate's ear is a thing (although it sounds like fun) but yes, they do contain urea hydrogen peroxide - see:[3]. Richerman (talk) 07:34, 9 February 2015 (UTC)

If Medeis were actually interested, she could have read the linked articles to verify it from a cited ref for this use, and the role of the urea in particular. DMacks (talk) 08:17, 9 February 2015 (UTC)

@DMacks - thank you for your help. I'd never have thought of a simple mechanical explanation like this. It's kind of like a mini massage :) 81.174.196.2 (talk) 16:07, 12 February 2015 (UTC)

Direction of Earth revolution

As you may know, the Earth is revolving around the Sun. In theory, a person standing on the Earth's surface should be able to hold out their arm and point in the direction of that movement. To stay pointing in the direction of revolution, their arm would move to compensate for both revolution and rotation.

Given a precise time and geographical location, it should be possible to calculate the direction to point. It shouldn't be all that difficult to build a device containing an accurate clock, a GPS receiver, and an arm mounted on two axes, which would keep its arm pointed in the direction of Earth's revolution at all times. Has such a device been built? If not, would you care to speculate why not?

You could also have a web page where one could enter their geographical location and it would give the direction to point as azimuth and elevation. Has such a web page been built? If not, would you care to speculate why not?

For that matter, you could have a continuously changing azimuth and elevation displayed on your computer screen at all times. Has such ... never mind.

Thank you for your consideration. ―Mandruss ☎ 20:14, 8 February 2015 (UTC)

Stellarium is worth a look.--Aspro (talk) 20:34, 8 February 2015 (UTC)

We even have a Stellarium (computer program) article for it:) DMacks (talk) 20:42, 8 February 2015 (UTC)

I don't think such a device has ever been built because not many people would see the point of it. (I'm happy to be proved wrong, of course!) Churches approximate the equivalent device for rotation of the Earth about its axis, of course, but not the velocity of orbit. It should be fairly easy to do in software and also to take into account the velocity of the sun in its orbit round the centre of the galaxy if you wish. I would speculate that this has not been done because yours is a minority interest. I haven't looked at Aspro's stellarium, but it sounds interesting. Does it have the facility that Mandruss is asking about? Dbfirs 20:40, 8 February 2015 (UTC)

Ah, but think of all the pointless, wonderful things that science museums have created for their exhibits, many of them spending tons of money in the process. Imagine what effect such a device might have on the mind of an eight-year-old child. They're all taught that the Earth is revolving around the Sun, but that's a very abstract and inaccessible concept until you say it's revolving that way. And to have that way be slightly different when they come back a few hours later. ―Mandruss ☎ 20:48, 8 February 2015 (UTC)

Are you following up on our replies or ignoring them just to beef off? Just show an eight-year-old child Stellarium and they will soon understand more than wot U does!--Aspro (talk) 21:02, 8 February 2015 (UTC)

Oh my, hostility. I wasn't expecting that at the Science Desk. Actually I was going to look deeper at Stellarium later, but when I briefly scanned its features "direction of Earth revolution" didn't jump out at me. ―Mandruss ☎ 21:06, 8 February 2015 (UTC)

OK, taken on board. Yet an an eight-year-old child ( I was one, a long, long time ago) doesn’t what to be feed spoon-fed factoids. Rather, they have have a hunger to understand the world and universe they where born into. Stellarium is a good staring point. In reply to Dbfirs... ( In a nice way – no just to avoid any chance of offense - but in way of further explanation) It is not 'my' Stellarium but an application I got lost in for a time. I now live in a city, with all the light pollution one expects from street lights extra, so I can't even see the Milky-Way no more. Stellarium took me back to my childhood, where a could stand, stare and wonder at Andromeda that was 2½ million light years away, etc. Now, all I can see in the the night sky, are aircraft coming into land.--Aspro (talk) 21:33, 8 February 2015 (UTC)

Sorry, I wasn't suggesting that you were in any way connected with the website, just acknowledging that you had given an interesting link (I must try it — though we don't suffer from much light pollution where I live, we do have more than our fair share of cloud cover, so I have to choose a rare clear night to see the Milky Way.) Rather than just a swinging pointer, I think Mandruss would appreciate a Stellarium combined with an Orrery. Dbfirs 21:52, 8 February 2015 (UTC)

Yes, a mechanical Orrery is great for understanding apparent retrograde motion. One can see it (and understand) with ones own eyes very quickly. Trying to fathom the same thing out from an encyclopedia (when your eight years old) -make one's brain hurt.--Aspro (talk) 22:15, 8 February 2015 (UTC)

Most of the motion of such a device would just be to swing in a daily circle to compensate for the earth's rotation on its axis. The plane of the circle would tilt with the seasons and be adjusted to account for local latitude, but that is basically it. Not a particularly interesting device in my personal estimation. If you are curious, for someone standing on the equator the direction of orbital motion is basically directly overhead at dawn and directly below the feet at sunset. Dragons flight (talk) 21:21, 8 February 2015 (UTC)

• As I may know, the Earth orbits the sun. Is there an actual question here? μηδείς (talk) 22:01, 8 February 2015 (UTC)

Shush!. The Pope may be reading this – do you want to be burned at the stake!--Aspro (talk) 22:21, 8 February 2015 (UTC)

The average heretic would concede that a hot stake is better than a cold chop. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:20, 9 February 2015 (UTC)

• • It was about whether anyone had ever constructed a pointer. We think not, for reasons outlined by Dragons flight. Dbfirs 22:05, 8 February 2015 (UTC)

This seems relatively trivial to do approximately. You point your fingers at the current position of the Sun, your thumb at the (unchanging) position of the North Star, and then the palm of your hand faces the way the Earth is moving ... provided that it's your left hand, and I didn't foul this up (50% chance, at least :) ). With a little correction for the minor eccentricity of the Earth's orbit. Of course, it's possible to do this more properly by marking the plane of the Zodiac and true north on an armillary sphere, but frankly, I think I'd only be more likely to confuse myself using it. :) Wnt (talk) 01:11, 9 February 2015 (UTC)