Wikipedia:Reference desk/Archives/Miscellaneous/2017 February 13

= February 13 =

Vykhino effect
If you're familiar with the Moscow Metro, you've probably heard of (or even personally experienced) the "Vykhino effect": at Vykhino station, because everyone transfers from the commuter train to the subway in order to save money on fares, during the morning rush hour the trains fill up so much that passengers often have to wait to board, and at all intermediate stations between Vykhino and Taganskaya, passengers can't board at all because the trains are so full (and because hardly anyone gets off at those stations during the morning rush hour, these being in working-class residential neighborhoods). My question is, is there a similar "Jamaica effect" in the New York subway at the Sutphin Boulevard-Archer Avenue-JFK Airport station, where the subway connects with both LIRR and the AirTrain JFK? And if so, what other well-known examples of this effect are there in other rapid transit systems? 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 02:02, 13 February 2017 (UTC)
 * I'm unfamiliar with the Moscow fare structure, but in London, which has a zone system, we have similar problems.  At Stratford, which is served by long and short distance commuter trains and also the terminal of the Jubilee underground line, commuters fill the Jubilee line trains to capacity, so that as they pass through "working-class residential neighbourhoods" (e.g.East Ham) nobody can board.   The trains empty at Canary Wharf, which is the financial district. 86.151.49.189 (talk) 06:38, 13 February 2017 (UTC)
 * Actually, we get this in our local bus system here in our Florida city. There's a commuter bus for students and employees that runs between the main campus and some residential complexes. There are also several intermediate bus stops between the complexes where commuters on the main drag can get on board. However, the bus almost always drives by those stops because they've been filled up from the beginning stops. This is a common logistical nightmare in commuter mass transit systems, and one that engineers don't really have an answer for, save to deploy additional buses on these routes at more frequent rates to accommodate the overflow in these circumstances.--WaltCip (talk) 13:33, 13 February 2017 (UTC)
 * Also see crush load.--WaltCip (talk) 13:35, 13 February 2017 (UTC)
 * Thanks, all, but I was asking specifically about overloading of rapid transit systems at points where they connect with commuter rail (such as Vykhino, Sutphin-Archer, or Stratford), due to passengers transferring from the latter to the former -- not about general overloading of public transit during rush hour. 2601:646:8E01:7E0B:9076:92A3:E19C:2F76 (talk) 11:01, 14 February 2017 (UTC)
 * One option, which some subway systems use, is scheduled Skip-stop service: Usually this involves running express trains and local trains on the same line: express trains pick up at the terminal stations and then skip the middle-range stations, dropping off at the city center. Local trains pick up at the stops skipped by the express, and also drop off at the city center.  For the evening rush, the system is reversed.  An example of this is the Purple Line and Red Line on Chicago's north side.  The Purple acts as an express for the northern suburbs, while the Red acts as a local for the city neighborhoods; both then let off at The Loop. -- Jayron 32 14:01, 13 February 2017 (UTC)
 * Excuse me, but skip-stop service does not involve express trains: see the article. There are only two ways an express train can gain time over local trains: either (A) it uses a separate track to pass them, or (B) the local trains are scheduled so far apart that the expresses merely catch up on them and don't have to pass them.  Method A is used on many lines in New York, and on a few places in other cities, including Chicago's Purple Line (see Jayron's link), Philadelphia's Broad Street Line, and London's Metropolitan Line (where the Jubilee Line is the local service).  Method B is not used on any rapid transit system today that I know about, but it was used in the past in London (where the term "non-stop" was used for express trains).  Skip-stop service involves different trains skipping different stops so that they all take about the same time and don't need to pass each other; this was also used in London at one time, as well as Chicago, but was abandoned. It still remains on some lines in New York. --76.71.6.254 (talk) 20:23, 13 February 2017 (UTC)
 * Incidentally, I happen to have another question about express/skip-stop subway trains, but I think I'll ask it later. 2601:646:8E01:7E0B:9076:92A3:E19C:2F76 (talk) 11:01, 14 February 2017 (UTC)
 * There are "all stations services" on the Metropolitan Line as well as the fast ones.  The Jubilee line serves stations which were formerly part of the Bakerloo line. 156.61.250.250 (talk) 14:43, 14 February 2017 (UTC)
 * And it's a 4-track line, just like the ones in New York -- except the track layout is backwards, with the local trains on the inside tracks and the expresses on the outside (whereas in New York the expresses almost always run on the inside tracks). 2601:646:8E01:7E0B:64B4:64AD:FCBF:2883 (talk) 09:24, 15 February 2017 (UTC)
 * I don't think the Jamaica effect would be strong because it's a fairly long subway trip from that station to Manhattan (it would make many commutes well over an hour), they wouldn't save much compared to their income, JFK flyers usually have luggage and many would avoid taking luggage on the train in rush hour. Sagittarian Milky Way (talk) 09:37, 15 February 2017 (UTC)
 * Just checked the timetables (happened to have them open because I was looking at routes and times for the Subway Challenge -- 42 minutes from Jamaica to Times Square on the E train, 47 minutes from Jamaica to Broad Street on the J/Z train. Whereas staying on the LIRR would get you from Jamaica to Penn Station in 20 minutes or so. 2601:646:8E01:7E0B:64B4:64AD:FCBF:2883 (talk) 12:25, 15 February 2017 (UTC)

Ships on the horizon [header added]
Down by the sea, I was watching ships through my 12 power binoculars. One thing I noticed is ships right on the edge of the horizon looked lower. I could only see the tops of the ship's (and we're talking huge mega tankers here) it's as if the sea was higher closer to me. Was the fact the ship's dipped on the far edge of the horizon due to the curvature of the earth? Or am I just imagining things here... — Preceding unsigned comment added by 77.71.228.239 (talk) 08:58, 13 February 2017 (UTC)
 * Yes, this is a real effect caused by the curvature of the Earth - for example, see this Youtube video of a ship sailing over the horizon. You can calculate roughly how much of the ship is hidden by the Earth, but mirages mean that it won't be exact - the light will probably be bent a little bit, and you might see some fata morgana. Smurrayinchester 11:30, 13 February 2017 (UTC)
 * See also Horizon. PrimeHunter (talk) 12:23, 13 February 2017 (UTC)


 * Athough I don't see it in Wikipedia articles, I've heard it said that one reason the ancients suspected the earth was round was because a distant ship would disappear below the horizon while its mast was still visible. ←Baseball Bugs What's up, Doc? carrots→ 13:28, 13 February 2017 (UTC)
 * Spherical Earth (subsection Strabo) mentions that elevated lights or areas of land were visible to sailors at greater distances than those less elevated, and stated that the curvature of the sea was obviously responsible for this. Loraof (talk) 15:07, 13 February 2017 (UTC)
 * Another way to see this effect is to look a suitable distance across water toward the skyline of a city. If you're familiar with the city's appearance from a nearer position, you can see how the bottoms of the tall buildings are missing. I remember observing this by looking at Toronto as seen across part of Lake Ontario from the Garden City Skyway. --76.71.6.254 (talk) 20:27, 13 February 2017 (UTC)


 * I don't want to start a huge debate, but this effect could also be explained if the Earth was flat and accelerating upwards at the rate of gravity. At some distance from an observer standing on shore, the light coming from what we call the horizon would not reach him because the upward movement of the sea would block it. My comprehension of calculus is not good enough. What I'd like is for some math genius to calculate with differential equations, what that distance would be, given the speed of light and upward acceleration of the Earth at 9.81 metres/sec/sec.
 * About 50 years ago, my father demonstrated an interesting optical illusion to me. Taking a long straight pole, he asked me to grasp it at its centre with one hand and hold out my arm at full length in front of my face so that the pole was horizontal. To my astonishment, the pole appeared to droop towards the ends, yet it was rigid and absolutely straight! How could this be? Akld guy (talk) 20:36, 13 February 2017 (UTC)
 * I'm not going to do the whole general relativity stuff right now, but a quick back of the envelope calculation: A yacht's mast is something around 10 metres. It would take about 1.5 seconds for light the sea to travel this distance. In this time, light will have travelled 450,000,000 miles, roughly the distance from Earth to the moon. While I don't know how much relativity would change this, it's not looking good. To recreate the curvature of the Earth on a flat disk would need the force of gravity/acceleration to be somewhere in the vicinity of a billion times stronger. (An alternative, easy way to see where this goes wrong - according to Einstein, gravity in an inertial frame of reference is indistinguishable from fictitious forces in an accelerating frame of reference. We live in a gravitational field of 9.81 N/kg which feels like standing on an accelerating disk at 9.81 m/s/s - if this was enough to bend light noticeably at the surface of the earth, we would see it every time we used a laser pointer - the laser beam would droop hugely towards the ground) Smurrayinchester 23:08, 13 February 2017 (UTC)
 * 1.5 seconds? Akld guy (talk) 23:34, 13 February 2017 (UTC)
 * Yeah, not sure where he got that. As famously used by Grace Hopper in her lectures on data transfer, light travels about 30 centimeters in a nanosecond.  In 1.5 seconds it goes much farther than 10 meters!  -- Jayron 32 03:43, 14 February 2017 (UTC)
 * He means that in 1.5 seconds, the sea will move up 10 meters, from a standing start. As to general relativity, I don't think it would change anything, since we are in the Newtonian (low gravity) limit. However, if we are talking a society so ancient they weren't sure if the Earth was round, they probably also don't know about the speed of light or the equivalence principle. Someguy1221 (talk) 03:53, 14 February 2017 (UTC)
 * Oops, yes, silly mistake. Smurrayinchester 08:56, 14 February 2017 (UTC)


 * This light-bending effect does exist, but it's extremely small (as Smurrayinchester said), and also you have the sign backwards: it makes the ship appear higher, not lower. You can see why in this image (which is not at all to scale) from the article Atmospheric refraction. S' (the apparent location of the Sun) is above S (its actual location). -- BenRG (talk) 08:56, 15 February 2017 (UTC)

Photo check
I received by email a bunch of photos without exif metadata and with strangely small resolutions (roughly between 300x600 and 600x600 px), but my several checks on whether they could be genuine were inconclusive (i.e. reverse search found nothing and no indication of digital retouching). Their default filenames are like "Image80", "Image243", etc. Imageedited.com only suggested that "based on the pixels, this image could have been created with" GIMP-like software (IrfanView, Photomatix, etc.). Is it more indicative of genuine pics or fake ones? Or the metadata was simply deleted? For good-faith reasons, I don't want to ask the sender directly whether they are genuine. Brandmeistertalk  19:12, 13 February 2017 (UTC)


 * Not all cameras even create EXIF data. Is there some content-based reason you question the photos? Because size alone is kind of a weird thing to be suspicious of, imo. Perhaps the sender used an email program that automatically reduces photo resolution. Recall 600x600 is more pixels than a whole VGA screen, and there was a time when that might have been considered a high resolution photo :) SemanticMantis (talk) 19:38, 13 February 2017 (UTC)
 * Ok. I had mild suspicions of scam, partially because even smartphones now shoot at more than 1,000 px by default. Maybe they were resized indeed. Brandmeistertalk  20:40, 13 February 2017 (UTC)
 * To be clear, I'm only offering an opinion, because I have never heard of small size being an indication of deceitful manipulation, and I couldn't find any references suggesting that. On the other hand, it does have a certain sort of logic: artefacts of manipulation may be harder to detect after decreasing resolution... Sorry, I'll come back if I find any actual refs. SemanticMantis (talk) 20:55, 13 February 2017 (UTC)


 * If you’re that curious, why not ask the sender for a few copies of the RAW or full JPEG's of your favourites? Sent one-at-a-time they should be able to pass through the email-server were as a big download may not. Which is why they may have been reduced before sending. Also, if both you and the sender have a FTP client then use that, as file size does not matter.--Aspro (talk) 00:02, 14 February 2017 (UTC)


 * This discussion is a bit vague. Perhaps you could upload an example. Also what do you suspect? What exactly do you mean by genuine? Downsizing and stripping exif may be a routine operation, but in itself it doesn't make a picture fake. Also note that all professional photographers and many amateurs edit all of their work in one way or another. In other words, we need a more precise question for a useful discussion. Jahoe (talk) 12:26, 14 February 2017 (UTC)