Wikipedia:Reference desk/Archives/Miscellaneous/2009 October 30

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October 30

Completing a 5-min Run in 4-min

Suppose your coach tells you to go running for 5 minutes. Is it possible to complete the run in 4 minutes? At first glance, by definition, the run is determined by time, 5 mins, so no matter how fast you run, you still have to do 5 minutes of running. But what if we were to apply some of Einstein's relativity theory to it? If I was to go faster than the speed of light or something, will it be possible then to complete a 5 minute run in 4 minutes? Acceptable (talk) 02:26, 30 October 2009 (UTC)

If you were able to run faster than the speed of light, you probably wouldn't need a coach. And you would probably finish the run before you started. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:29, 30 October 2009 (UTC)

Please regard this as a hypothetical question of theory. Acceptable (talk) 02:39, 30 October 2009 (UTC)

Yes, you can. If you run at 0.6c (ignoring acceleration/deceleration times) 4 minutes in your frame of reference will correspond to 5 minutes in the coach's frame (assuming he is not running alongside you, in which case you are out of loopholes). See Twin paradox for more deatils of the phenomenon. Abecedare (talk) 02:53, 30 October 2009 (UTC)

But if the runner's own clock only reads 4 minutes, has he really lived up to the coach's order? ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:43, 30 October 2009 (UTC)

A spinoff question would be, at that speed, how many laps would that be around a typical quarter-mile track? Assuming he's got really high-quality track shoes (Nike's finest) which enable him to go around each semi-circle at roughly 112,000 miles per second, that would be about 450,000 times around the track in one second; 27,000,000 times in one minute; and 135,000,000 times in 5 minutes - or 4 minutes. Either way, he still has to go around the track 135,000,000 times. Right? ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:55, 30 October 2009 (UTC)

That's not what the OP asked for. It was a simple mathematical question: at what speed v is the Lorentz factor equal to 5/4? --PalaceGuard008 (Talk) 04:21, 30 October 2009 (UTC)

The runner would be in an accelerated frame going round the circuit so fast, wouldn't that slow them down a bit more again? Dmcq (talk) 14:28, 30 October 2009 (UTC)

His body structure would fly apart as he tried to turn in such a short radius at 0.6c He would literally have to withstand millions or even billions of g's in acceleration. Googlemeister (talk) 16:29, 30 October 2009 (UTC)

I think that's why he would need the special shoes. UltraExactZZ ^Claims ~ Evidence 17:38, 30 October 2009 (UTC)

I'm seeing Spike Lee now: "It's gotta be the shoes!" I was assuming a standard oval track. But if it was a great-circle track around the world, that would eliminate the issue of turns (never mind how they would build a track across the oceans - that's a different question). But in any case, if you had to go around an oval quarter-mile track 135,000,000 times, the great circle route of 25,000 miles would be 100,000 times as long as that track, hence "only" requiring about 1,350 circuits of the globe in those 5 (or 4) minutes, or 270 circuits in 1 minute, or an average of 4 1/2 times around the world per second. It would now be interesting to see how many times in one second that Superman flew around the world in the 1978 film. Anything less than 7 1/2 trips around the world would mean he's not actually exceeding the speed of light, and hence couldn't "reverse time". ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:14, 31 October 2009 (UTC)

It's never clear to me why anyone would think that travelling faster than light would "reverse time". Aside from the complete impossibility of doing it - what the equations suggest might hypothetically happen is something akin to taking the square root of -1...your experience of the rate time passing in the rest of the universe would be a complex number. But complex numbers never appear in the results of real-world calculations. It's impossible to say what it would hypothetically mean to someone if they experienced a lorentz contraction that was a complex number. That in no way even hints at a reversal of time...it hints at something so completely beyond comprehension as to be literally indescribable.

Fortunately (or not), Nature has a way of protecting us from such ugly math problems. For example - the equation for the period of the swing of a pendulum has a square root in it - so the time that a pendulum of negative length would take to swing would be a complex number...but nature doesn't allow us to make physical objects with negative length - so the question never crops up. In this case, the protection against tripping over a complex number is that you can't go faster than light - period. SteveBaker (talk) 12:45, 2 November 2009 (UTC)

A great-circle path does not eliminate "turns", it just means that the "turn" is in a different direction. He still needs magic shoes to cling to the track to provide that acceleration, and a non-magic body would still be pulled apart by the forces needed to produce the acceleration. Dbfirs 10:22, 3 November 2009 (UTC)

What luggage should we buy? (to use it as check in luggage)

If you are open to flying with any air company, but do always want to check in with your trolley, what measure should your trolley have? I have researcher online and found the following extreme values: from 43 cm x 28 cm x 20 cm to 56 cm x 45 cm x 25 cm. Of course, I won't buy anything bigger than the highest allowance. I was thinking to buy something near 50 cm x 40 x 20 and try to fly with it even if the company has a lower allowance. The question is how tolerant are companies of minor deviances of a couple of centimeters? --Quest09 (talk) 11:50, 30 October 2009 (UTC)

Company tolerances vary considerably. Then again some institute a 'blitz' for a short time. The only way to be sure is to visit the sites of the airlines you most use and check individually. Also remember that the luggage regulations vary with the class of ticket you pay for. Travel First and almost anything goes. Travel cattle and you'll be cramped. Finally, you can often get by with flexible luggage. Sports bags, etc. These squeeze down and often fit where a hard case would not. Finally, finally, check out the carry-on allowance. The maximise what you are allowed. i.e. a large handbag (purse) for a lady... good luck.Froggie34 (talk) 12:15, 30 October 2009 (UTC)

Hand baggage regulations are also imposed by the airports. As well as checking with the company you're flying with, you should check with the airport(s) you're checking in at. Don't forget that many places forbid the carriage of large volumes of fluids. --Phil Holmes (talk) 13:57, 30 October 2009 (UTC)

Yes, the regulation regarding fluids in the European Union is still in force. I wonder why liquids have to be carried in single containers with a capacity not greater than 100 ml, being a half-full 200 ml container not permitted, and all of these single containers must be packed in one transparent, re-sealable plastic bag with a capacity not greater than 1 liter. Quest09 (talk) 16:47, 30 October 2009 (UTC)

The article on this is 2006 transatlantic aircraft plot security reaction, and it was caused by the 2006 transatlantic aircraft plot. Comet Tuttle (talk) 17:13, 30 October 2009 (UTC)

And why is the regulation the way it is? Why is half-full 200ml not acceptable? Why should the bag be re-sealable? Why do you have to divide everything in small bottles? --Quest09 (talk) 18:50, 30 October 2009 (UTC)

Because the people who make rules like this are not grounded in reality. Or at least the version of reality that applies outside their government building. Googlemeister (talk) 19:16, 30 October 2009 (UTC)

See Security theater. Having rules makes people think that action is being taken which is likely to keep them safer. You are not actually safer; but it makes you think that you are. See my response to a similar question below. --Jayron32 19:33, 30 October 2009 (UTC)

You're going overboard with theatrics about security theater. You are asserting that increased analysis of passengers' carry-on liquids makes airline travel actually 0% safer, which I disagree with. Comet Tuttle (talk) 21:25, 30 October 2009 (UTC)

It's not about 0% safer, it's about the trade-off between measures taken and security gained. In general airplane security does not have a good track record—it costs a huge amount of money and we don't get much for it. Bruce Schneir has written quite extensively on this, and it is quite good analysis, and he knows of what he speaks. Check it out. There's an argument, for example, that regulations of this sort lead travel security people to focus on the wrong sorts of things when they are evaluating the overall threat assessment of a given person—if true, that means that they are actually doing less than increasing security 0%. If people (and security folks) feel more secure than they are, then your security theater has created an atmosphere of less security than you had when you started. --Mr.98 (talk) 01:09, 31 October 2009 (UTC)

I'm not disputing that the carried-on-liquids rules may not be worth their costs. I'm disputing the claims above that they increase security by 0% (or less). I think such claims are silly. And the claim that "The TSA must be overlooking important vectors of attack because of the carried-on-liquids rules" is pure speculation. Comet Tuttle (talk) 03:02, 31 October 2009 (UTC)

Perhaps the belief is it's easy to mix explosives if you have a larger container. Of course it would seem likely you could just mix the explosives in the 1l plastic bag you're required to carry anyway. It may not be as easy, but it would seem likely to be good enough. (Also according to below you can just buy a large bottle after you've passed security.) The reason for transparent/resealable should be obvious. The reason for single bag I suspect is more to do with convenience for the security staff. If you have passengers pulling 3 bottles out of various pockets of their bags it's going to waste more time then if they are all in one place. Edit: Another thing that occured to me is that a half empty container could also be partly for the convenience of security. If you have a 1 litre container which you say is only 100 ml full security may have to look at it carefully to make sure this is really the case since 1) A 1 litre container can vary significantly in shape so working out whether a container is really 1 litre and if so whether it really contains 100ml only is likely to be more difficult then working out if a container is really a 100ml container and 2) They have to actually check the container only contains 100 ml as you claim and not more, rather then just go by the container size. For example, you could have to liquids that don't mix and one of them is highly transparent and above the other one or if the container is not very transclucent. This would at a minimum likely require shaking the container and obviously looking a lot more carefully then just glancing at the containers, it may even require opening it. 2 doesn't apply to the examples when you are talking about a single large container that is under the total limit allow for liquid vs 5x100 ml (or whatever). 1 does apply to some extent and I guess there could also be a 'simple examplanation' thing. Saying you're allow 5 containers of up to 100 ml each is simpler then saying you're allowed 5 container of up to 100 ml each or 1 container of 500ml or anything in between (saying you're allowed one or multiple containers with a total combined volume of 500ml kind of works but may cause further confusion) Nil Einne (talk) 08:05, 31 October 2009 (UTC)

It depends totally on the airline, and the cost of the ticket is often related to the amount of leeway you are given in terms of hand bag size. I have witnessed a furious row between a passenger and a check-in girl who refused to allow an item of hand baggage even though it fitted into the size checker, because she said the bag's little plastic feet protruded above the top rail of the checker (they did, by about 4mm tops) and because the bag had been pushed down into the size checker instead of dropping in with no resistance. This was with a no-frills airline. The bag was eventually checked in at extra cost, and the passenger loudly announced his determination never to travel with that company again. The only safe answer is to check the individual airline's rules and ensure you more than abide by them. Karenjc 20:18, 30 October 2009 (UTC)

Question about school policy

Why don't schools allow us to go on social networking sites when in a study hall? it seams like if you don't have many schoolwork to do, and the site doesn't contain any malicious software it should be allowed.Accdude92 (talk to me!) (sign) 15:21, 30 October 2009 (UTC)

Every school will have its own rules and ideas about these things. Their logic is likely to be that social-networking sites are a distraction from school-work. They don't know if you are or are not busy in your studies, but they expect that the site will reduce likelihood of doing the work. There's plenty of debate on this subject across businesses too - my office allows Facebook but plenty don't, it's partially a question of trust I guess. 194.221.133.226 (talk) 15:57, 30 October 2009 (UTC)

A further consideration is how many computers with internet access the school has and how they are charged for access. If there aren't enough for everyone to access the internet at the same time, the school won't want to waste a terminal on someone visiting a networking site in case someone else wants to use it for work. And if the school is paying for internet access in any way other than unlimited broadband at a set cost and very high speed, they won't want people using the connection for things other than work, particularly if the sites they visit show a lot of pictures and videos. 86.139.237.128 (talk) 16:02, 30 October 2009 (UTC)

Furthermore, you always have schoolwork to do. You have tests to study for, papers to write which are due in a week or two, textbooks which contain review problems which, while not assigned for a grade, still exist and you could still do them to give you more practice. The deal is, there is school work that you do not want to do during study hall. It doesn't mean that you don't have anything school-related you could be working on. --Jayron32 16:37, 30 October 2009 (UTC)

Well, it all depends - if there's so much H1N1 around that teachs dont' assign much schoolwork, or the person is just really fast, they could still do work ahead, but near the end of the year, there might not be. But, that's when you can work on something you like for the future. I know a guy who tried to write a book during part of study hall, so writing is one avenue you can explore. Or, anything you're interested in going into in college, should you choose to go.4.68.248.130 (talk) 17:38, 30 October 2009 (UTC)

(ec) A sentence that starts with "it seams like if you don't have many schoolwork to do," seems to imply exactly the opposite. Aside from that, Facebook and MySpace have historically been quite efficient avenues for distributing malware. --LarryMac | Talk 16:38, 30 October 2009 (UTC)

To clarify LarryMacs comment - if you don't have any other school work to do, you should work on your spelling and grammar. --Tango (talk) 18:08, 30 October 2009 (UTC)

Let's be honest -- no one here learned spelling and grammar by studying it intensively -- you just pick it up over the years. Vranak (talk) 18:21, 30 October 2009 (UTC)

And you learn it largely by reading and writing; hence, if one has no school work to do, get a library book and try reading a bit... --Jayron32 19:30, 30 October 2009 (UTC)

I agree. Reading is the best way to learn good English. --Tango (talk) 19:42, 30 October 2009 (UTC)

The point remains: one does not 'work on one's spelling or grammar' per se, past junior high. Vranak (talk) 20:29, 30 October 2009 (UTC)

Just because you did not have to doesn't mean other people do not have to, and do not do it. Comet Tuttle (talk) 20:48, 30 October 2009 (UTC)

The ones who gripe about me going off-track ought to read this thread. Here's the deal: The school owns the computers and they have the right to determine how they're being used. If you're going to a news site like CNN, that's presumably a good thing, as it could be expanding your knowledge of current events - and improving your reading skills. If you're going to chat rooms, that's not a good thing. You're in school to study; you can socialize at appropriate times, like in the lunchroom. There could also be bandwidth issues. That's one reason why Youtube is blocked at my office. Another is that it's likely not work-related. It is very unlikely, in an industrial company, to find something on Youtube that's vital to watch during working hours. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:03, 31 October 2009 (UTC)

I was reading a book on grammar just last week and I'm a long way past junior high. --Tango (talk) 01:30, 31 October 2009 (UTC)

I never tire of looking things up in the dictionary, and reading in general. But in my day, it was toward the end of what you might call the "pedantic" approach to schooling. It seems to have shifted toward another direction now, where somehow good English is not important. And someday, it's going to cost us dearly. I've met some people who said, "I don't like to read." What can you feel for that, except sadness for what they're missing. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:19, 31 October 2009 (UTC)

Never forget Accdude that these so called social networking sites are about selling you a product. They are a business. Undoubtedly they are distraction for vulnerable individuals who cannot distinguish between the relative social value of an education and logging on to Facebook and similar. It is quite clear that some people need to concentrate on their education. Caesar's Daddy (talk) 16:17, 31 October 2009 (UTC)

(Oh, how high-minded and moral we all are, all of us who probably edit the Ref Desk while at work, school, and so forth. Get to the school, young man. Study and be diligent and avoid distractions. Just like how we did when we were in school, and we had to walk uphill both ways, in the snow, at that.) --Mr.98 (talk) 19:54, 31 October 2009 (UTC)

Walking to school would have been luxury for us. We had to crawl down the mine all day. But we were happy. Cuddlyable3 (talk) 21:02, 31 October 2009 (UTC)

Ah, memories of Gym class! "Those who can't do, teach. And those who can't teach, teach Gym." --Woody Allen. In any case, we didn't have computer terminals in my day, all we had were manual typewriters. Not much internet surfing on those babies. Although every generation thinks it has it tough. I'm hearing Larry Miller's prospective comment to his son someday: "In my day, we didn't have jet-packs; we had to drive to school!" ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:24, 31 October 2009 (UTC)

no liquids can be brought on commercial flights

Does the rule in the US that all liquids brought into the cabin of a commercial airliner be in tiny bottles and sealed in a plastic bag include the crew? For example, if the pilot wants to bring a thermos of coffee with him for the flight, will it get taken from him by the security drones? Googlemeister (talk) 18:48, 30 October 2009 (UTC)

Pilots do have to pass through the security checkpoints, so I would assume that this rule applies to them. Marco polo (talk) 19:08, 30 October 2009 (UTC)

Actually, once you pass through the security checkpoint, you can purchase a coffee or a bottle of water and safely bring it on the plane. Most moderate-to-large sized airports have plenty of vendors on the "safe" side of security; no one checks you once you have passed through that point, so pilots should be able to buy a cup of coffee like anyone else and get on the plane. Pilots and other airline workers have "break rooms" and pilots lounges where they can get coffee; they could presumably get coffee there and bring it aboard. Most planes I know also have a pot brewing on the plane itself, so the fact that pilots cannot bring an actual cup through the checkpoint should provide little impediment to getting coffee to fly with. Security is generally only handled at the checkpoint; furthermore there is still very little security at the "back doors" of airports. Workers that do not enter through the traveller checkpoints aren't subjected to the same level of scrutiny that travellers are; that gives way to the criticism that the whole system is Security theater; designed to make passengers feel like the industry is doing something to keep them safe; but a determined terrorist would still have little to no trouble getting a bomb on board a plane. Have a nice trip! --Jayron32 19:27, 30 October 2009 (UTC)

As a passenger in both in Australia and Britain, I have taken an empty plastic bottle with me and filled it up on the "safe" side from a drinking fountain. The security people didn't question it. Saves a heap of money too!--80.176.225.249 (talk) 21:03, 30 October 2009 (UTC)

What is this rule for? I can't think of any purpose, though I'm sure there is one. —Akrabbim^talk 21:09, 30 October 2009 (UTC)

See 2006 transatlantic aircraft plot security reaction and 2006 transatlantic aircraft plot. Bad guys were going to sneak explosives onto the planes in bottles. By reducing the amount of carry-on liquids that can be brought aboard — and having an emphasis on security personnel analyzing passengers' liquids in the first place — the theory is that the risk of a repeat of this plot is reduced. Comet Tuttle (talk) 21:22, 30 October 2009 (UTC)

There is a strong argument that this is just security theater—something that makes it look like security agencies are doing "something", but doesn't actually increase security. A nice write-up of this particular argument is: "The Things He Carried", from the Atlantic Monthly, 2008. --Mr.98 (talk) 01:04, 31 October 2009 (UTC)

Reportedly if you merely claim the liquid is medically necessary, such as contact lens fluid or baby formula, there are no limits, implying it is all theater. Edison (talk) 01:19, 31 October 2009 (UTC)

Baby formula you are usually made to taste to show it isn't liquid explosive. I'm not sure about contact lens solution... --Tango (talk) 01:28, 31 October 2009 (UTC)

I mistakenly left my contact lens solution in my carry-on luggage recently and they let me bring it on the plane. The thing that annoys me most about the liquids thing is the 100ml limit. It seems pointless, since anyone wanting to bring on, say 200ml of liquid explosive would simply carry on two bottles. --Richardrj ^{talk email} 09:05, 2 November 2009 (UTC)

The taste thing is an interesting issue. Provided you can avoid showing too much aversion to the liquid, the only question is whether it's possible to have liquid explosives which won't kill you (or make you too sick to follow through the plan) within a few hours. If you can then it's not likely to be effective except that if the person decides not to follow thorough with the plan after they've passed security they may still die. Nil Einne (talk) 08:12, 31 October 2009 (UTC)

I see. That's kinda what I figured, but wasn't sure. Anyway, this is what sparked the question in my mind. —Akrabbim^talk 02:54, 31 October 2009 (UTC)

-Flight crewmembers are exempt from the liquids ban in the United States

RETAIL MARKET

There was a company named AMNES retail store which was the biggest competitor of WAL-MART some 10 years ago. But I dindn't find that company. Can you please provide me the details. —Preceding unsigned comment added by Kunjal88 (talk • contribs) 19:35, 30 October 2009 (UTC)

Did you mean Ames Stores? They went bankrupt in 2002, according to the article. Bielle (talk) 20:07, 30 October 2009 (UTC)

New Listing for Scottsdale Arabian Horse Show

This event is the world's largest Arabian horse event. It attracts thousands of Arabian horses from all over the world and around 250,000 human spectators each year. How would I go about putting together a listing for it? It is a non-profit event benefiting childrens charities. I am not very tech savvy but would love to do something to get this event the listing as they really deserve to be part of Wikipedia. —Preceding unsigned comment added by Owensharkey (talk • contribs) 22:40, 30 October 2009 (UTC)

There is a mention of it at Scottsdale, Arizona#Annual cultural events and fairs, but you're right that there is no article. (The word 'listing' suggests to me that you're thinking of this as a directory or guidebook, but it's not: it's an encyclopaedia). If you know something about the Show, and you have some reliable sources for the information, why don't you try writing an article? Read Your first article carefully first, though. --ColinFine (talk) 00:36, 31 October 2009 (UTC)

You may be interested in WikiTravel. Dismas|^(talk) 02:26, 31 October 2009 (UTC)

Having Trouble Staying Logged In Wikipedia

Dear Wikipedia, I use your website all the time but lately every time I come here I have to log in when it Remember up to 30 days it hasn't been 30 days its like the day when I have to log in again, please help me I really love website I wanted stay logged in for a while that is up to the 30 days not the day where I need sign in again.

Love, Angela :-) —Preceding unsigned comment added by Dancingteen (talk • contribs) 23:24, 30 October 2009 (UTC)

Do you have your web browsing software (i.e. Internet Explorer, Firefox etc) set up to accept cookies? If not then you will keep getting asked for your password. Change your setup to accept cookies and that might solve the problem. --Richardrj ^{talk email} 23:34, 30 October 2009 (UTC)

It can also help to delete all your Wikipedia cookies. See also Help:Logging in for tips on staying logged in.--Shantavira|^{feed me} 07:29, 31 October 2009 (UTC)