Science desk
< March 11	<< Feb \| March \| Apr >>	March 13 >

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.

March 12

Is Earth getting bigger? If so, why?

Hi guys. In the NatGeo or BBC docus I see, all things historic (fossils, towns) are excavated from meters below the present ground level. The historic ages are mapped as per the depth of the excavation below ground level. This seems to point to the fact that the Earth is getting bigger. Is this the right perception? If it is getting bigger, how is that happening? Is it because of space dust or any other reason? Thanks. Lourdes 04:46, 12 March 2017 (UTC)[reply]

The ground in some areas tends to accumulate and uplift. Check your local cemetery and notice how flat-ground markers appear to be "sinking" due to vegetation and soil accumulation. ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:50, 12 March 2017 (UTC)[reply]

(edit conflict) Earth isn't gaining appreciable mass, or at least that's not the reasons behind what you see in archaeological excavations. (In fact it's generally thought that Earth is slowly losing mass.) There are various ways for things to get buried: natural processes such as deposition of material from rivers or glaciers (as in the famous Gården under Sandet in Greenland), mounding-up of material as a city decays and is rebuilt (see Tell (archaeology)), and so on. Shock Brigade Harvester Boris (talk) 05:01, 12 March 2017 (UTC)[reply]

Also note that the depth/age evaluation relationship is always specific to that location, a particular depth is not universally of the same age everywhere. Various dating methods are used to determine the age of a particular layer at a particular location. Layers of great depths can also be revealed in mountains, because of the tectonic processes which formed them. PaleoNeonate (talk) 05:27, 12 March 2017 (UTC)[reply]

We also have an article on the falsified Expanding Earth hypothesis. PaleoNeonate (talk) 08:21, 12 March 2017 (UTC)[reply]

Maybe we should also point out that the material that accumulates on top ultimately comes from the interior of the Earth - either as sedimental material removed by Erosion and deposited on top by wind or water, or, in the case of organic material, as carbon that outgassed (mostly in the form of CO2) and was converted by photosynthesis into more complex molecules. It's a cycle, not a one-way street. --Stephan Schulz (talk) 08:45, 12 March 2017 (UTC)[reply]

... and don't forget the worms. This article is interesting (in spite of it containing an image of an inappropriate worm) it decribes the general principle and importance. Richard Avery (talk) 12:04, 12 March 2017 (UTC)[reply]

Thanks everybody for the interesting replies (the video feature too Richard). What about the supposed 4000 tons of cosmic dust being loaded onto Earth annually, as per New York Times?^[1] Lourdes 13:23, 12 March 2017 (UTC)[reply]

Our article you linked to suggests 40k may be a better number. But regardless, while this may seem a lot compared to masses you encounter in the everyday world, considering earth mass is

(5.9722 \pm 0.0006) \times 1024 kg

you're talking about a ~6.7e-16% increase. In other words, not even close to the margin of error of our best estimate of the earth's mass. Also you're ignoring losses, our article on the earth's mass suggests there's a net loss and the part on being a net loss is sourced to this [2]. There's also a source for loss of gasses which is where nearly all the loss is. (It also provides a range for cosmic dust.) Nil Einne (talk) 14:40, 12 March 2017 (UTC)[reply]

(edit conflict) Earth is big. The surface area is 510,072,000 km². 4000 tons equally distributed would be 0.00000784 g/m². Earth's mean density is 5.514 g/cm³. Even if we assume a low density of 1 g/cm³ for the dust, it would only correspond to a layer of 0.000000000784 cm per year. That corresponds to 3.56 cm in 4.54 billion years. Earth was clearly hit harder in the past. PrimeHunter (talk) 14:41, 12 March 2017 (UTC)[reply]

This explains the mass gain/loss formula that is generally excepted as being most probable. Earth Loses 50,000 Tonnes of Mass Every Year. The Mice which had planet Earth built for them, may well have more accurate figures. --Aspro (talk) 14:51, 12 March 2017 (UTC)[reply]

Impressive analysis. Thanks all. I leave with a better understanding. Lourdes 15:16, 12 March 2017 (UTC)[reply]

Yup, see: Atmospheric escape#Dominant atmospheric escape and loss processes on Earth. Praemonitus (talk) 19:52, 14 March 2017 (UTC)[reply]

Golden gun

In Scaramanga's golden gun, how is the breech kept closed during firing? In other words, what keeps it from backfiring in his face every time he pulls the trigger? 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 07:05, 12 March 2017 (UTC)[reply]

Book or movie? — Preceding unsigned comment added by 71.85.51.150 (talk) 12:49, 12 March 2017 (UTC)[reply]

Here is a video of the film-prop version replica being assembled, but I have no idea how the breech would stay closed during firing. Alansplodge (talk) 15:24, 12 March 2017 (UTC)[reply]

Neither do I -- that's why I'm asking! Because I've already seen the video, and to me it looks like the breech (closed only by the flip-top of the lighter) should burst open on each and every shot! (Neither is there any striker visible for actually firing the cartridge, but that's not completely implausible because the gun could be rimfire or even electrically fired -- but there must be some way to seal the breech, or it simply wouldn't work!) 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 10:55, 13 March 2017 (UTC)[reply]

There is no evidence of any firing pin. The shell is smooth, so it cannot be clipped in place. The only reasonable method of firing would be electrical, which implies that it would be possible to use an electromagnet to hold the lighter lid in place. Also note that the bullet itself must be very low powder if it were truly a golden gun because a normal bullet would heavily deform a truly golden gun. So, the force of the explosion must be very low in firearm standards, implying that it would be much easier to hold the lighter lid shut. This all goes along with the novel in which the golden gun is lethal because the bullet is poisoned, not because the velocity of the bullet is extremely dangerous. 209.149.113.5 (talk) 11:35, 13 March 2017 (UTC)[reply]

At least the book version is described as "gold plated", not massive gold (which presumably would melt from the heat of the powder, and which is to soft to hold any rifling pattern). Also see Jayron below ;-). --Stephan Schulz (talk) 22:26, 13 March 2017 (UTC)[reply]

Fiction keeps it from backfiring into his face. --Jayron 32 12:10, 13 March 2017 (UTC)[reply]

Any sufficiently advanced technology... seriously, you could postulate all sorts of tricks. Like, maybe there are indentations (not seen) around the base of the bullet into which sliding gold-plated pins move, perhaps to administer an electric current across the powder charge whilst holding the shell casing firmly from moving backward. This is a fine exercise for creative writing - I think I could come up with four more ideas. Wnt (talk) 23:31, 13 March 2017 (UTC)[reply]

Clarke's third law just for those unfamiliar. --Jayron 32 02:22, 14 March 2017 (UTC)[reply]

Well, I've just realized there's no need to apply Clarke's third law -- the most plausible explanation is Martini-Henry action. (I have no proof, though -- this is simply the most straightforward mechanism I could come up with, according to Occam's razor.) 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 10:45, 14 March 2017 (UTC)[reply]

There's no need to invent an actual explanation on your own. The only explanation is what Ian Flemming wrote in The Man with the Golden Gun (novel) or what the prop masters created for The Man with the Golden Gun (film). If Flemming wrote no explanation into the text of his book, the question has no answer. --Jayron 32 12:24, 14 March 2017 (UTC)[reply]

As noted above, the book described a gold-plated Derringer with poisoned bullets. The movie invented a complex mess of gold objects that somehow snap together. So, the book version works just fine. There are many gold-plated guns that work. The movie version is a bit absurd. 209.149.113.5 (talk) 12:59, 14 March 2017 (UTC)[reply]

Golden gun, part 2

Although Scaramanga boasted that he "only needs one shot" to kill his targets, how is this possible with the dinky little 17-caliber gun that he had? Specifically, even if one makes a 17-caliber hollow-point bullet out of solid gold (which would increase momentum and thereby stopping power), and loads the cartridge with enough propellant to give the same muzzle velocity as for a standard 17-caliber bullet, would this give enough stopping power to reliably stop (let alone kill) a person with only 1 shot? 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 08:03, 12 March 2017 (UTC)[reply]

As part of the (fictional) narrative, he simply is that good (or claims to be). Killing in one shot with a BL 15 is not a mark of great skill. With a small caliber, you have to aim not just at the person, but at a particular part of the person. --Stephan Schulz (talk) 08:40, 12 March 2017 (UTC)[reply]

All right, I consider the original question answered -- but this brings up a second question: Is it possible, with a 17-caliber pistol (and one with a removable barrel, at that -- removable barrel = at least some free play between the barrel and receiver = less accuracy), to reliably hit a person's vital organs at anything beyond point-blank range? 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 09:33, 12 March 2017 (UTC)[reply]

Well, at the 50 meter pistol event, the world record is 583 out of 600 with 60 shots. The size of the 10-ring is 5 cm. The shooters use a single-shot .22 caliber pistol. So I would think that, especially with artistic license, this is possible. Note that the movie "Golden Gun" also is a single-shot weapon, which I suspect can be inherently manufactured to greater accuracy than repeating weapons. Of course, in more realistic scenarios like World War II or the current War on Terror, it takes something like 10⁵ bullets (give or take an order of magnitude or two - well, probably give 2-3 orders of magnitude [3]) to kill one opponent - and that's mostly military rifle ammunition. --Stephan Schulz (talk) 10:24, 12 March 2017 (UTC)[reply]

Bear in mind that that figure will include a lot of shots being fired on automatic, without necessarily taking much care to aim, sometimes without actually trying to hit a specific enemy, and possibly without actually confirming the location or identity of the target. A better comparison for Scaramanger's capabilities would probably would probably be a proper sniper. Iapetus (talk) 17:25, 13 March 2017 (UTC)[reply]

True, but, does a target pistol's barrel unscrew from the chamber like the golden gun's pen-barrel does? Because this would reduce accuracy. (I also noticed that the golden gun had no sights -- how much would that reduce accuracy?) 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 11:02, 13 March 2017 (UTC)[reply]

Also, gold is almost twice as dense as lead so you'll have a small but heavy bullet.--TMCk (talk) 14:50, 12 March 2017 (UTC)[reply]

Looking at real examples, the Sleeve Gun, a single-shot assassination weapon developed by the Special Operations Executive (with which Ian Flemming was associated) was "intended for use in contact with the target, but may be used at ranges of up to about three yards". It had a calibre of 0.32" (8.1 mm) Alansplodge (talk) 15:34, 12 March 2017 (UTC)[reply]

But a 32-caliber bullet is a lot bigger than a 17-caliber one, right? 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 11:02, 13 March 2017 (UTC)[reply]

The US Air Force had a bullpup stockless automatic rifle prototype made up chambered in .17 Remington Fireball during the later years of the Vietnam Conflict but it never saw production. The clear implication is that the caliber was considered lethal enough to be a protective weapon for downed pilots (it was thin enough to be part of the survival kit tethered to the ejection package of a fighter aircraft). loupgarous (talk) 00:44, 13 March 2017 (UTC)[reply]

Fossils and igneous rock

Hello Guys i have a curosity that why is fossil not presented in the igneous rocks ?? Since fossils are the dead bodies of plants and animals preserved inside the earth ,Then there should be more fossils in the igneous rocks coming during volcanic eruption,but I had studied that it is not presented in the igneous rocks ??Can any one tell me ?? Sawongam (talk) 14:35, 12 March 2017 (UTC)[reply]

If you look at Igneous rock you will see why. It starts out molten from deeper inside the Earth. If the the volcanic output is from a subduction zone, any physical morphic fossils evidence would be destroyed. It depends of cause on your definition of fossil evidence. The gasses emitted from volcanoes who magma derives from from a subduction zone marine of sediment have been found to have an oxygen isotope ratio showing that its origin is marine. This is because the marine creatures biology favour one of the oxygen isotopes rather than other and thus concentrate it. To my mind these gases comes under the very broadest term used for fossilized evidence. Volcanic ash 'deposits' however, can often preserve thing like human foot prints. So ingenious doesn't contain morphic fossils.--Aspro (talk) 15:25, 12 March 2017 (UTC)[reply]

In general fossils are found in the sedimentary rock that formed the land surface or the bottom of the sea where the animal/plant whose remains were fossilised lived. Living things that are in the path of lava or pyroclastic flows get incinerated. See Pompeii for an example of how at least the shape of humans and other animals remains can be preserved in a pyroclastic flow deposit. Mikenorton (talk) 15:29, 12 March 2017 (UTC)[reply]

The only igneous rock with a chance of containing fossils is an airfall tuff, a deposit made from fine-grained ash that has settled out of the atmosphere - still uncommon though (see page 153 for an example). Mikenorton (talk) 15:50, 12 March 2017 (UTC)[reply]

In addition to the issue of the heat incinerating the body, even if that doesn't happen, there's also the question of what would stop decomposition. There are already microbes in the body capable of destroying it, once dead, so merely being sealed off from the outside world is not enough to protect it. Chemistry in places like peat bogs acts as a natural preservatives to kill those microbes. A common process for fossil formation is if water flows into a cavity left from a body that decomposed, and forms rock there by deposition. I suppose that's possible if the cavity was formed by an animal killed by volcanism, but then it's a sedimentary fossil, not volcanic. As for a later lava flow filling in the gap, that would tend to crack or melt the old lava rock, so would be unlikely to leave a recognizable fossil. StuRat (talk) 16:54, 12 March 2017 (UTC)[reply]

Chemical fossil microbes (cryptoendoliths) have been found in gas bubble cavities (see: vesicular texture and amygdules) in pillow lava, for example in Devonian pillow lava in Germany and in more recent Quaternary pillow lava of the Kolbeinsey Ridge (part of the Mid-Atlantic Ridge, north of Iceland). GeoWriter (talk) 18:22, 12 March 2017 (UTC)[reply]

Two examples of fossils in volcanic ash fall deposits are the John Day Fossil Beds National Monument of Oregon, and the Ashfall Fossil Beds of Nebraska. GeoWriter (talk) 18:32, 12 March 2017 (UTC)[reply]

Well Thanks guys for your informatiom,I got it Sawongam (talk) 01:59, 13 March 2017 (UTC)[reply]

Quadratic field strength

Could you please provide a good source for a definition of the "quadratic field strength" of a stellar magnetic field? I know "quadratic field strength" can be used for magnetic field measurements in the case of complex magnetic fields, but I can't find a good explanation. Thank you. Praemonitus (talk) 17:26, 12 March 2017 (UTC)[reply]

This phrase does not have any particular meaning. Unless you specify a context where you want to use it, the phrase is pretty meaningless. Ruslik_Zero 20:00, 12 March 2017 (UTC)[reply]

Well, for example, Bychkov et al (2009). Praemonitus (talk) 19:29, 13 March 2017 (UTC)[reply]

In Section 3 (page 1339, right column), they say 'In Paper 1, we used the term "the average quadratic magnetic field" instead of rmslmfs', where that abbreviation means 'root mean square longitudinal magnetic field strength' as defined in Equation 1. So, 'quadratic' here means the 'square' in 'root mean square'. --Wrongfilter (talk) 19:35, 13 March 2017 (UTC)[reply]

The discussion was a little confusing to me since they talk about changing the terminology in that paper away from 'average quadratic field strength' equating to 'rmslmfs'. But I guess I'll go with that. Thanks. Praemonitus (talk) 21:45, 13 March 2017 (UTC)[reply]

Digital radio coverage in underground railway tunnels

How is digital radio coverage achieved in underground railway tunnels? Is it through masts within the tunnel which provide coverage throughout the whole tunnel or is it through masts in the train which provides coverage within trains only and the signal comes from either the rails or through masts within the tunnel? — Preceding unsigned comment added by 2A02:C7D:B989:5E00:648B:B127:5B62:1A4E (talk) 19:12, 12 March 2017 (UTC)[reply]

Where?

Both those ideas are in use. 86.20.193.222 (talk) 19:35, 12 March 2017 (UTC)[reply]

"Masts" don't propagate well in tunnels. A leaky feeder is more commonly used. This is a length of cable (similar to antenna feeder cable) that radiates weakly all along its length. Andy Dingley (talk) 19:49, 12 March 2017 (UTC)[reply]

One doesn't need masts in a tunnel, just a arial repeater wire along the roof. It been used for decades. Think it is referred to by a fancier name along the lines of 'leaky coax'. It has low attenuation of the signal and doesn't produce high nodes and low nodes but gives continuous reception along its length. Sure other editor will fill in the technical details. --Aspro (talk) 20:13, 12 March 2017 (UTC)[reply]

Some relatively short tunnels do use actual (directional) antennas for mobile (cell) phone signals, which I presume are broadly comparable. I know this because I used to work (on the admin side) for a company who were tasked (by the actual operators via their Facilities Maintenance providers) to repair and replace such antennas (most often on rooftops or towers, of course), and we had a few callouts to deal with antennas in tunnels, most notably the Dartford Tunnels (where the initial problem was locating the antenna in the first place – a lot of mobile phone infrastructure is appallingly poorly documented). {The poster formerly known as 87.81.230.195} 90.202.209.145 (talk) 21:35, 12 March 2017 (UTC)[reply]

Bug identification

Hi! Can anyone identify this bug for me, please? I found it in Israel today and, unfortunately, it had been squished. But it's still pretty visible. Here's a picture: http://imgur.com/PPBcAwR It's about 6-7mm not including whatever's sticking out of it. (When I say bug I mean an insect or crustacean or something, not a "true bug".) Thank you so much! 195.192.224.237 (talk) 19:34, 12 March 2017 (UTC)[reply]

Could be a Silverfish.--TMCk (talk) 19:50, 12 March 2017 (UTC)[reply]

I have the same impression. PaleoNeonate (talk) 20:10, 12 March 2017 (UTC)[reply]

German cockroach with an ootheca and a detached antenna near it's butt? Maybe not. Sagittarian Milky Way (talk) 20:13, 12 March 2017 (UTC)[reply]

Thank you! 195.192.224.237 (talk) 20:34, 12 March 2017 (UTC)[reply]

Rudolph Valentino's death

The article Valentino's syndrome says that Rudolph Valentino died due to a infection contracted during a failed attempt to repair a perforated peptic ulcer. I would like to know if perforated peptic ulcers can sometimes heal without treatment and if, consequently, Valentino's death could at least theoretically have been avoided had the doctors not intervened. Thanks in advance. --Schweinchen (talk) 21:08, 12 March 2017 (UTC)[reply]

I suppose theoretically it's possible, but it's much more likely that you'll die without treatment. See gastrointestinal perforation. Money quote: "Even with maximum treatment the risk of death can be as high as 50%." Of course, in Valentino's case, antibiotics weren't available at the time, which meant your prognosis wasn't great regardless of what the doctors did. --47.138.163.230 (talk) 21:49, 12 March 2017 (UTC)[reply]

Thank you. Do you have any sources? --Schweinchen (talk) 22:22, 12 March 2017 (UTC)[reply]

There was a link to the relevant article - is there a particular point or phrase you'd like backed up? Rudolph Valentino died in 1926. Antibiotics had been the subject of research by then, but Fleming's work with penicillin wasn't until after Valentino was dead and antibiotics weren't generally available outside of the military until much later. Matt Deres (talk) 00:10, 13 March 2017 (UTC)[reply]

The article doesn't actually provide the citation (aside from a name and year) and I'm not sure if it's a garble. I mean, having a perforation in your GI tract tends to cause infection. I found this which says that one case was managed conservatively with antibiotics and another treated by laparoscopy. It's clear that he didn't need his appendix removed, and of course I suppose unnecessary surgery doesn't help with an infection. I should look a little further though. Wnt (talk) 00:29, 13 March 2017 (UTC)[reply]

The original antibiotics and the only ones available in America at the time of Valentino's death were salvarsan and other arsenic derivatives used for treating syphilis - and considered much too toxic for prophylaxis against post-operative infections. Bayer's work (under Domagk) on the sulfa drugs hadn't been complete until about 1933. loupgarous (talk) 00:49, 13 March 2017 (UTC)[reply]

I am not sure if "meh" is verboten zdyes comme en ITN, but I fell out of my chair at work the Saturday after Thanksgiving after 9/11 and assumed the fetal position since it was too painful to cry out. It was diverticulitis. I don't think we can diagnose things here, including the deaths of dead people. μηδείς (talk) 20:41, 13 March 2017 (UTC)[reply]

Here is his death certificate:[4] ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:13, 13 March 2017 (UTC)[reply]