Wikipedia:Reference desk/Archives/Science/2015 February 18

= February 18 =

Cell Phone for Use in Europe
If this isn't the right desk, then should I post to the Miscellaneous desk? I will be going to Rome over the night of Thursday, 20 February through Friday, 21 February, via Frankfurt and want to be able to call or at least text my daughter and other family members to let them know that I have arrived safely. I spoke to my cellular carrier, Verizon, and they tried to be helpful, but were not. They said that I should have called them earlier so that they could have sent me a temporary phone. They said that I can buy a pre-paid phone in Europe. That is all right, but I asked if I could buy a pre-paid phone that will work in Europe and in North America while I am still in North America. They said no. Is that correct? Do I really have to wait until I get to Frankfurt to let my family know that I am in Europe? Was my carrier being straight with me in saying that I can't do anything until I get to Europe, or can I get a pre-paid phone in the US that I can use in Europe to text or call the United States? Robert McClenon (talk) 03:14, 18 February 2015 (UTC)


 * Phones that work in both the U.S. and Europe are increasingly common (I have a couple). What model phone do you have now? It just might work in Europe. Short Brigade Harvester Boris (talk) 03:20, 18 February 2015 (UTC)


 * The model that I have is a flip-phone that my carrier said will not work in Europe. I believe them on that point.  My real question is only whether I can get a phone at the airport that will work in Europe.  The technical services person said that I can't get one here, and have to get it in Europe.  She may be right, but I would guess that she doesn't know something, which is why I am asking.  Robert McClenon (talk) 03:36, 18 February 2015 (UTC)


 * You absolutely can get a phone here that will work in Europe.
 * A little technical mumbo-jumbo: Your Verizon phone uses a technology called CDMA. Europe (and almost everywhere else in the world) uses a technology called GSM. That's why your current phone won't work over there.
 * In the U.S. both AT&T and T-Mobile use GSM. Although they use different frequency bands than European carriers it's common to find "quad band" phones that work in both Europe and the U.S. One such is the Moto E available at BestBuy for $119. There are two models of the Moto E: a "global GSM" and a "U.S. GSM" model. Both have the same voice frequencies and should work for voice, text, and 2G data in both Europe and the U.S. (I have no experience with this model but according to the specs it should.) The difference is that the U.S. model replaces the European 3G frequency bands with T-Mobile's oddball frequency bands for 3G data.
 * If you don't care about high-speed data overseas I'd go with the "U.S. GSM" model and T-Mobile's pre-paid plan. From what I can tell it will let you send text messages from overseas for $0.50. Voice calls from overseas are very expensive -- they almost always are when roaming internationally with a prepaid plan -- but are tolerable for a quick emergency or safe-arrival call (full rate card here).
 * Hope this helps. I haven't actually used the Moto E but travel internationally a good deal, and from the specs this is how it should work (i.e., I'd be willing to spend my own money on it). You might try calling T-Mo to check, but often the front-line support staff don't know much about these more uncommon issues, as you have found with Verizon. Short Brigade Harvester Boris (talk) 03:59, 18 February 2015 (UTC)
 * There's always the easier option of finding the nearest Wifi and using VoIP/Whatapp or internet based messaging services. Fgf10 (talk) 07:47, 18 February 2015 (UTC)
 * ...or, thinking outside the box, use a phone booth. They get rarer, but should still be around in very central locations like airports. --Stephan Schulz (talk) 09:48, 18 February 2015 (UTC)
 * Finding wifi doesn't help you if you don't have a device which can use it. Or to put it a different way, if the OP is planning to take a laptop or tablet or something perhaps this will work. However if all they're taking is their flip phone, I'm not sure this will have wifi, in which case finding wifi will be of no use. They could buy a cheap smart phone with wifi, but unless this is something they want, it's probably more cost effective to either just get a cheap phone with quad band GSM, or to get a phone in Europe is, as suggested below. (You could probably also buy a dual band or triple band phone that is designed for European markets in the US, but I strongly suspect buying a quad band phone in the US would be easier and probably cheaper too.) By cheap phone I'm thinking something probably under USD25. Nil Einne (talk) 13:05, 18 February 2015 (UTC)

What busters did cancel the regime (status) of plug and play in telephony?--83.237.219.81 (talk) 09:23, 18 February 2015 (UTC)
 * If you only want a basic mobile phone (no web browsing, and no or very poor camera), then you can get them for €20, and a pay as you go SIM. Lyca and Lebara offer cheap international calls, back to the US/Canada. If you only want to make calls in the European country you are in, then pick any local SIM. In any case, you will probably be asked for your address, you can normally use your hotel's address. LongHairedFop (talk) 11:00, 18 February 2015 (UTC)

Internet connection: charging by the time or amount?
Why is Internet (when it is not flat rate) charged by amount of information, and not connection time? I am thinking in 3G, and 4G plans. --Fend 83 (talk) 13:10, 18 February 2015 (UTC)


 * Because "connections" are (nearly) free, while data transfer is not. The Internet Protocol is packet-oriented. You don't "rent a line" to "the internet" that is exclusively yours, but you rather send an addressed chunk of data through the net. It's more like the postal service, where you buy stamps for each message you send, not like a cable provider that gives you an exclusive cable (and signal), wether you use it or not. --Stephan Schulz (talk) 15:05, 18 February 2015 (UTC)


 * In a phone call, you're sending data continuously at a fixed rate - so the amount of time is a direct measure of the amount of data you're sending. When you're surfing the web, you're typically only consuming data when (for example) you load a new page - once it's loaded you can have it on the screen for minutes, hours or days without consuming any more data, so charging by time doesn't make any sense.  So, in effect, you're being charged for the amount of data you send and receive in both cases - it's just that in the case of a phone call, it's easier to think of it in terms of "minutes" rather than megabytes.


 * The network doesn't really care how long something takes - only how much of it's limited data capacity you're consuming...so that's what you're paying for.


 * SteveBaker (talk) 15:06, 18 February 2015 (UTC)


 * But there was a time were dial-up internet ruled. And if I am right, this was charged by the minute, not the KB. Couldn't they have allowed users to connect all the time they wanted, but charged them by the data, to limit its use? Fend 83 (talk) 15:51, 18 February 2015 (UTC)


 * Yes, but that would have kept the phone line open whenever they were logged on, making it unavailable for anyone else. This would result in people leaving their PCs online all the time, but doing very little data transfer, since the price per data transfer would have to be very high.  Also, monitoring the amount of data transfer wouldn't be automatic with such a system, you'd basically have to add hardware to eavesdrop on the line to figure out how much data was being transferred. StuRat (talk) 15:57, 18 February 2015 (UTC)


 * There seems to be some confusion here. There are two components that may arise for dialup internet connection charges. One is the cost you may pay to your telecommunications provider, in other words the company providing you your phone line. The other is what you pay to the internet service provider, the company who provide your internet connection. Depending on a variety of local stuff, you may only may one of these, the companies may be the same, or the fees may be combined. But in terms of your internet service provider, there would be no need to eavesdrop on any line, and no reason why monitoring the amount of data transfer would be any more or less automatic (whatever you mean by that) than mobile connections, or wifi, or DSL or whatever. It would basically work in a similar fashion (monitor data transfer through some router). Now if your telco wanted to charge by data transferred, (which makes almost no sense, at least your ISP charging makes a small amount of sense), they would need to either get this info from the ISP, or eavesdrop on the line, but I'm not sure if that's what the OP was suggested.Nil Einne (talk) 16:11, 18 February 2015 (UTC)


 * I believe the usual arrangement was for it to be a local call from the home to the ISP, and local calls were typically charged per call rather than per minute, at least in the US. At that point the ISP paid for the call from there on, and billed the customer accordingly.  Since they would have used long distance phone lines in those days, and have been billed per minute by the carrier, they would naturally want to pass that per minute rate on to their customers (usually they did this by billing a fixed amount for a given number of minutes, then either cut you off or charged more if you went over). StuRat (talk) 16:24, 18 February 2015 (UTC)


 * More generally, whenever you price something in a way that doesn't match the true cost to the supplier, you will get problems. For example, if a landlord includes utilities "for free", then tenants will be wasteful of those utilities, doing things like leaving windows open in winter in rooms they want a little cooler.  Ultimately this will lead the landlord to raise the rent, or limit heat to everyone, so everybody loses in the end.  Then competition will kick in, and another landlord with a more sensible billing policy will get the tenants moving in there, forcing the first landlord to change his policy or go bankrupt.  StuRat (talk) 15:57, 18 February 2015 (UTC)


 * ...and this is already happening. Voice call rates are generally priced *WAY* higher than the amount of data they actually produce/consume.  That causes customers to use VOIP services (things like Skype and Magic Jack) that convert your voice call into data packets that the phone company cannot easily distinguish from other kinds of data transfer.  Telephone-quality speech generally consumes around 8k bits per second.  A single image on a web page can easily require a hundred to maybe a thousand times that.  If you have a couple of gigabytes of data per month included for free in your phone service agreement - then that's equivalent to maybe 500 HOURS of voice calls.  By any reasonable standards, voice calls over digital networks should be free.  SteveBaker (talk) 20:20, 18 February 2015 (UTC)


 * Agreed, although a live phone call (as opposed to voice mail) does have an additional requirement that the signal be sent in real time. While delays of a few seconds are no problem when sending a pic, they would be a nightmare during a phone call.  So, this higher level of service justifies some difference in pricing. StuRat (talk) 17:02, 22 February 2015 (UTC)

MH370 radio
I haven't yet noticed much about radio signals aspect in the MH370 story, so thought of two things (seemingly not mentioned in our article). First, can the ATC controllers actually tell, whether the radio transmitter used for communication with ATC is switched off in the aircraft, similar to phone signals, telling the calling person whether a particular phone is busy or turned off?

Secondly, since the radio signals from the ATC bounce off from the aircraft regardless whether the onboard radio is switched off or not, was it possible for ATC to track the flight via Doppler effect by repeatedly contacting MH370, measure the radio signals that bounce off from it and doing the related math? Brandmeistertalk  18:12, 18 February 2015 (UTC)


 * The Doppler effect would only tell you the speed at which the plane was moving towards or away from the observer, and I doubt if they have it set up to detect even that. StuRat (talk) 18:17, 18 February 2015 (UTC)


 * Besides, that's what radar does...they already have radar systems - why have their voice radio duplicating that function? The problem with radar (and using voice radio to perform the same trick) is a matter of range. For a voice transmission to get someplace, it has to cover some distance or other...for radar to work, the signal has to be bounced off of the aircraft and reflected back to the transmitter.  Right there, you've doubled the range that the signal has to travel...which means that you need four times as much power to make it detectable.   In practice, it's worse than that because the curved surfaces of the aircraft tend to scatter the signal all over the place, so the amount of the reflected signal getting back to the source is small.  Radar systems are designed with enough power - and at a frequency - where these problems are minimized - voice radio is not.


 * As for whether the ATC operators can tell if the radio is turned on or not - well, no - they could only possibly tell if the radio was actively transmitting (like if the pilot has his thumb on the "TALK" button)...and ordinarily, pilots are trained to avoid transmitting when it's not strictly necessary in order to avoid interference with other aircraft - so an always-on transmitter would be a bad idea for long-range communication. SteveBaker (talk) 20:08, 18 February 2015 (UTC)


 * As somebody who lives and breathes the RADAR equation, I'm obliged to remind our esteemed Steve Baker that RADAR power goes as $$\frac{1}{R^4}$$. At twice the distance, you need sixteen times as much transmitter power for the same signal-to-noise ratio.  This order of magnitude is not something to scoff at.  Nimur (talk) 21:54, 18 February 2015 (UTC)


 * Hypoxia may have set in - that only applies to a passive target. The transmitters signal decays at R^-2. So if the base station pings the a/c and it broadcasts in response, the R^-2 equation applies Greglocock (talk) 22:14, 18 February 2015 (UTC)
 * I thought we were talking about primary returns... but yes, if you're including a transponder or other secondary surveillance radar, ... but then your transmitter power needs to be set to the power of the aircraft's squawk box, not the gigantic megawatt-scale ground-station ! Nimur (talk) 22:22, 18 February 2015 (UTC)
 * Yes, and radar requires a direct line of sight to work, so the curvature of the Earth gets in the way. Some forms of radio, though, like ham radio can bounce between the sky and the surface repeatedly to go halfway around the world. StuRat (talk) 22:03, 18 February 2015 (UTC)


 * "radar requires a direct line of sight to work" more bollox from the man who knows everything. JORN. Greglocock (talk) 02:25, 20 February 2015 (UTC)


 * Over-the-horizon radar demonstrates that you don't need a line of sight. So, while Greglocock is guilty of violating WP:NPA - it's true that StuRat is incorrect in this case. SteveBaker (talk) 16:10, 20 February 2015 (UTC)


 * I wasn't wrong, I just need to clarify my response: "The type of radar typically used at commercial airports requires a direct line of sight". Since the Q is about tracking commercial airplanes, this is the relevant type of radar. StuRat (talk) 16:56, 22 February 2015 (UTC)

Planting milkweed and Monarch butterfly--when and where is it helpful?
Lots of us are planting milkweed to try to prevent the monarch butterfly from going extinct. But I have read on the web that this can be sometimes counterproductive. Is it a location or timing thing? Where in the United States is it helpful or at least harmless and where is it harmful? Exactly what is the reason for planting milkweed to sometimes paradoxically harm monarch butterflies?155.97.8.213 (talk) 22:42, 18 February 2015 (UTC)


 * My understanding is that milkweed needs to be planted in sufficient quality and in a large enough area in order for it to be useful. One plant in a backyard mostly tree-shaded will be of little use.  (I read this within the last week or so, but don't have a source.  In NYC this is pointless, but my parents live in a formerly rural suburban area with a lot of open space.  I'd contact the local municipality and ask if they have something like open space areas like they do in NJ. μηδείς (talk) 22:55, 18 February 2015 (UTC)


 * See Monarch butterfly decline: Monsanto&rsquo;s Roundup is killing milkweed.
 * —Wavelength (talk) 23:04, 18 February 2015 (UTC)


 * You are defaming Monsanto. Roundup is an herbicide designed to kill plants.  There is nothing wrong with their product.  It's like blaming Ginsu knives for stabbings. μηδείς (talk) 01:19, 19 February 2015 (UTC)
 * Where I come from, milkweed is considered a noxious weed. As to the Roundup complaint, an even better analogy is that it's like complaining if Raid were to kill your pet preying mantis. ←Baseball Bugs What's up, Doc? carrots→ 01:27, 19 February 2015 (UTC)
 * For the correct spelling, see praying mantis.—Wavelength (talk) 02:01, 19 February 2015 (UTC)
 * Probably praying it doesn't get hit by Raid. ←Baseball Bugs What's up, Doc? carrots→ 02:43, 19 February 2015 (UTC)
 * And your grandfather didn't consider clover a weed. Weed is a cultural definition, not a scientific one. SemanticMantis (talk) 15:06, 19 February 2015 (UTC)
 * Yes, cultural, hence the "where I come from." And how do you know what either of my grandfathers thought of clover? ←Baseball Bugs What's up, Doc? carrots→ 01:52, 20 February 2015 (UTC)


 * Surely you are joking. In case you are not - What utter dross. We cannot defame with scientific observations. Glyphosate is applied at extremely high rates across the USA, over 91k tons per year (NASS data here ). "Roundup ready" crops developed by Monsanto lead to the creation of glyphosate resistance in weeds, which leads to even more roundup usage, in a vicious cycle of positive feedback. Gene escape has been discovered in many Brassica strains, including rapeseed. Roundup is relatively safe in small applications, but dousing half the country with it every year tends to fuck things up, with respect to our soil, our native plants, our water ways, and many other natural systems. These are all documented in our article, along with many citations to peer-reviewed sources. As I said, Roundup is not the worst pesticide ever. But the incredibly high usage rates are still the cause of many negative impacts to our agriucultural systems and natural ecosystems. Remember, the dose makes the poison, and our dose of glyphosate in the USA is extremely high. Worldwide, roundup is applied to roughly the area of two Californias, and most of that is in the USA, as related by Genetically_modified_crops. So I think I have plenty of room to criticize both Monsanto, and the farmers who use RR crops, all while staying very clear of "defamation". SemanticMantis (talk) 15:06, 19 February 2015 (UTC)
 * I am not going to respond to that directly, I just don't want my silence to imply I concede or agree μηδείς (talk) 17:51, 19 February 2015 (UTC)
 * Can you show us a source that says it's counterproductive? I'm somewhat familiar with recent research in conservation biology, restoration ecology and even butterfly gardens, and I have never heard that claim. Another thing to point out is that Monarchs aren't really in danger of going extinct in their near future, it's the migration that is endangered. See e.g. here, which quote the WWF scientist as saying "The monarch butterfly as a species is not endangered. What is endangered is its migratory phenomenon from Canada to Mexico and back."
 * Anyway, burden of proof applies here, and without a specific claim, much less supporting argument and citation, it's hard for me to refute. I will give some general info that might be helpful though -
 * If planted naturally, the "timing" probably isn't an issue. This would come under phenology. Now, there are concerns that phenological patterns may be breaking down due to climate change, but each individual plant and butterfly will be following its own cues for timing, and planting milkweed can't really change that.
 * The native range of Asclepias is huge in the USA e.g., so I don't think there will be any problems on that front.
 * Now, the one thing that could conceivably be true is this: if you were to grow lots of milkweed in greenhouses, and make sure there were always some in bloom, some always bolting, etc, then that artificial change to the phenology could possibly screw up the butterflies desire to migrate based on food scarcity. So maybe we shouldn't intentionally muck around trying to confuse the Monarchs.
 * The main point is, I believe, for most any home owner in the USA, planting common milkweed on their property can't actually harm the monarch species. SemanticMantis (talk) 23:55, 18 February 2015 (UTC)


 * Oh, sorry is it this ? It says that planting non-native species could be a problem, for pretty much exactly the reasons I said above - exotic milkweeds will bloom all year, and make migration less likely. Good news is, this is very simple, just make sure you plant common milkweed -- you'll have some nice flowers, help the monarch migration persist, and can't really go wrong :)
 * SemanticMantis (talk) 23:58, 18 February 2015 (UTC)


 * See The beautiful reason you should plant milkweed | MNN - Mother Nature Network for instructions.
 * —Wavelength (talk) 00:04, 19 February 2015 (UTC)


 * See Ask the Monarch Butterfly Expert: Dr. Karen Oberhauser.
 * —Wavelength (talk) 00:07, 19 February 2015 (UTC)


 * See http://monarchwatch.org/waystations/ - they produce a "Creating a Monarch Waystation" guide" and if there is a problem they will know about it. Richerman    (talk) 11:57, 19 February 2015 (UTC)