Wikipedia:Reference desk/Archives/Science/2015 September 3

= September 3 =

How will the Arx Pax "tractor beam" work?
A news story says NASA has hired a special effects company, Arx Pax, which simulated a "hover board" in a movie, to build a "tractor beam" to manipulate objects in space without touching them. I suppose electrostatic attraction or repulsion could achieve this, or magnetism to a lesser extent, but have any new discoveries in physics come along to allow "tractor beams" like in science fiction? See http://www.foxnews.com/tech/2015/09/02/nasa-taps-hoverboard-company-arx-pax-to-build-space-tractor-beam-technology/ Edison (talk) 03:56, 3 September 2015 (UTC)


 * That article says they will use "Magnetic Field Architecture (MFA) technology", which sounds like they are going for magnetic effects. This similar but slightly better article clarifies " But a space-based hover engine wouldn't draw spacecraft in from far away like a tractor beam from 'Star Trek.' We're talking on the scale of centimeters," Arx Pax co-founder and CEO Greg Henderson told The Verge." (Verge article here ) Finally, despite the confusing Fox piece, Arx Pax  doesn't seem to be a special effects company, one of their products just reminded people of the hoverboards from Back_to_the_Future_Part_II. SemanticMantis (talk) 14:01, 3 September 2015 (UTC)

‘Big Bang’ – ‘Protogalaxies’ - ‘Protostar’
I would like to understand the following in simple terms please, I'd be grateful.

When the universe was foggy (till to 380,000 yrs) as a result of the Big Bang, when did it become transparent?
 * 1) After 300,000 yrs, the protogalaxies were forming by creating stars - which definitely was resulting in smoky cloudings, and definitely other stars were getting created along with the centre/main one – then became transparent/were becoming transperent (at the same time).
 * 2) After 380,000, it became transparent, then stars began to form, creating smoky cloudings, and other stars were getting created along with the centre/main one as they were forming, then the outer nebula was shed to the ISM via the solar flares.

Space Ghost (talk) 19:41, 3 September 2015 (UTC)


 * The second statement is correct. According to our current estimates, it took hundreds of millions of years for the first stars to form. See chronology of the universe. Stars couldn't have formed before the universe became transparent. The very reason the universe was opaque before photon decoupling (to use the fancy physics term) is because it was so hot. Particles were constantly smashing into each other at enormous energies. No large-scale structures could form; the universe was just one nearly uniform soup of particles. Only as the universe continued to expand and cool could gravity begin to dominate and begin pulling matter together into stars and galaxies. On a side note, solar flares aren't primarily responsible for the shedding of a star's matter. They do cause matter to be ejected, but compared to the scale of a star, the amount is very small. It's difficult for us little humans to wrap our heads around how huge stars are. Most of a star's material gets released in one of two ways. Lower-mass stars on the main sequence eventually shed their outer layers as they transition to white dwarfs, creating a planetary nebula. This is the eventual fate of our Sun. More massive stars die in supernovas after exhausting their fuel, blasting their contents out into space. Stellar evolution has more details. --71.119.131.184 (talk) 00:12, 4 September 2015 (UTC)
 * Sad.png Okay, I'm taking your words for it. View the following article Galaxy - (press CTRL+F on the browsing tab after entering it then type 300,000), I guess I'm in the wrong here by not understanding the English properly... This article named Dark energy also had information about 300,000 yrs, how protogalaxies expanded after 300,000 yrs, I can't find it now. By the way, the confusion rests upon two things and they are: 1) Scientists recently found out that star formation could occur in a transparent place. 2) The universe was foggy as a result of the Big Bang so, regardless of the particle combinations, if I speak my mind, stars should've formed in the foggy zone at first, but it did not... If you wish to say anything whatsoever about these two points stated, you can say, anything you say would satisfy me... Thanks.
 * One last help now, with the Stellar Evolution article. I'll send the information tomorrow. Thanks in advance. Good night/day. -- Space Ghost (talk) 20:37, 4 September 2015 (UTC)
 * 71.119.131.184: The article Stellar evolution looks like its been renewed, it might take some time (few days/weeks) for me to reunderstand the article; I had problems understanding it the last (many) time(s). I will definately try my best this time because a Wikipedian advised to read it thoroughly - he did not know I had English understanding problem though. If there is a chance of getting in touch with you, let me know, otherwise, I'll just hope to see your message, like I do for Wikipedians.
 * Anyway, I'm grateful for your time spent upon me. And I very much believe that you'll make me understand the 'stellar evolution' article appropriately, in simple terms...
 * I'm not sure if I'll ever see your message, therefore I'd like to state in advance that, I believe that Big Bang occured from a star which followed the stellar evolution procedure; may be from a population IV star! This is as rational as multiverse hypothesis.
 * Regards -- Space Ghost (talk) 20:26, 5 September 2015 (UTC)
 * Sorry for the delay in replaying. Regarding star formation, I'm not quite sure what you're having trouble understanding; this is probably a language barrier issue. Yes, stars and protogalaxies started forming after decoupling, but that takes many millions of years. The universe's time scales are way longer than the time scales we puny humans are used to thinking about. It wasn't like the universe became transparent and then bam, stars blazed into existence almost immediately; rather, it was a slow process of gas and dust clumping together due to gravity, over many millions of years. It seems to me like you might be a little too hung up on the universe being transparent or opaque and how it would affect star formation. By itself, the universe being transparent or not has nothing to do it. If I understand what you mean, yes, it's not like stars can't form in "foggy" places. Indeed, nebulas are pretty foggy (at least, relative to the rest of the universe), and a lot of stars form in them. Rather, the reason stars didn't form before recombination is because all the matter in the universe was flying around at such high energies. Gravity is what forms stars, and gravity is the weakest fundamental force by far. Before recombination, and for some time afterward, the matter in the universe simply had too much kinetic energy for gravity to be able to start drawing it together into large structures. The universe being opaque to light was just another effect of its high temperature, not the reason why stars couldn't form. As for your idea about the universe's formation, hmm, that's definitely not the most out-there hypothesis I've heard. To be fair, the universe at the Big Bang was rather like the inside of a star: hot and dense. --71.119.131.184 (talk) 21:07, 6 September 2015 (UTC)
 * Do you want to hear something funny? I wrote 912 words by constantly re-reading your comment, after accomplishing it, I understood your comment fully when I begun re-reading it for the last time.
 * Anyway, I understand and I’m happy. Okay view the following. I'm using my previous knowledge of it. I've created another section because this one will soon disappear...
 * Space Ghost (talk) 21:40, 7 September 2015 (UTC)

Products that are (generally) better the more expensive they are?
Any thoughts? I know that it's not always (or even usually!) the case that the more you pay for something, the better it's going to be - but in a small number of cases, you really can get a good idea as to the quality of a product simply by looking at how much it costs... Whisk(e)y and wristwatches are two examples that I can think of. --87.113.134.86 (talk) 23:05, 3 September 2015 (UTC)
 * What is the basis for your premise? ←Baseball Bugs What's up, Doc? carrots→ 23:08, 3 September 2015 (UTC)


 * Wristwatch is a bad example. A digital clock is almost perfect (up to 1s per month imprecision), and it's much cheaper than luxury watches.
 * Maybe expensive education is always better than cheap education. Or expensive health care is better than cheap options. Or expensive consumer electronic devices are better. It's difficult to define better, btw.--YX-1000A (talk) 23:42, 3 September 2015 (UTC)


 * Flash cards. The price seems closely proportional to capacity.  But whiskey?  The best way to make that stuff taste good is to pour it out and refill the bottle with something else. :) Wnt (talk) 00:30, 4 September 2015 (UTC)


 * You, sir, don't know your whiskey. Someguy1221 (talk) 02:02, 4 September 2015 (UTC)
 * A man who presumably does know it wrote The Science and Commerce of Whisky. Might be better to start at page one. InedibleHulk (talk) 02:24, 4 September 2015 (UTC)


 * With all alcohol, going too cheap is often illegal. That's a British link, but not a uniquely British concept. InedibleHulk (talk) 02:29, 4 September 2015 (UTC)


 * I'm afraid the two examples you gave are likely the exact opposite of what you mean. Blind taste tests of wines have shown no correlation between price and quality. Luxury watches are also generally overpriced. Expensive liquors and jewellery tend to be Veblen goods; demand for them tends to go up with the price. Buying them is a form of conspicuous consumption, advertising to others that you can afford such an item. This isn't to say that there is absolutely no difference in quality between, say, a $5 digital watch and a Rolex, but that the difference is not commensurate with the price. And to be fair, there are some circumstances where a high-end watch is worth the price; U.S. astronauts have worn the Omega Speedmaster as well as a few other watches that are tested for use in space. Better examples are complex capital goods where there is a broad market for such goods. Automobiles are a great example. You can generally count on a luxury car being of higher quality than a cheap low-end car. This is not to suggest that a low-end car is useless, or that luxury cars never function as status symbols, but there's a fairly strong correlation between price and quality. --71.119.131.184 (talk) 00:42, 4 September 2015 (UTC)


 *  Blind taste tests of wines have shown no correlation between price and quality. cite please. From personal experience I find the 8 to 40 dollar bottle range is extremely efficiently priced by consumers. That is, I choose a 20 dollar bottle. It will be better than any 10 dollar bottle, it will usually be beaten by a 40 dollar bottle. Any 'bargains' rapidly get cleared off the shelves. here's a meta study http://ajae.oxfordjournals.org/content/early/2014/07/12/ajae.aau057.short . I noticed  a silly experiment got a lot of publicity where they tested various wines on non wine drinkers, and found to nobody's amazement that they preferred the cheap (sweet, fruity) stuff. Duh. Greglocock (talk) 19:51, 4 September 2015 (UTC)


 * I've tasted a (yearless?) red that comes in a 5 liter plastic bag in a cardboard box with a plastic spigot (cheap!) and it tastes like medicine. It was so dry (though maybe that's only single sec, I don't know). It needs some sugar, what's with the obsession with fine gradations of ultra sugarlessness and crud like tannins and lemon juice sourness? I kept repeating the algorithm 1. add water to the cup 2. drink a sip 3. go to line 1 to see if there's a point it's even drinkable and it basically tasted like sour water with 1% alcohol at the end. I think should've found out how much sugar would've made it drinkable. Maybe it'd take enough to make it like melted candy, lol. Sagittarian Milky Way (talk) 22:07, 4 September 2015 (UTC)
 * If you like slideshow-style articles based on Reddit posts, has Business Insider got a deal for you! Sixteen generic things and a Tempur-Pedic mattress for just one click. By clicking, you agree to click again for each individual item, and offer requires permission for businessinsider.com and jquery.com to run Javascript, because advertising is expensive and cheap. InedibleHulk (talk) 01:59, 4 September 2015 (UTC)


 * And 13 Things You're Better Off Buying Used, with the same caveats. InedibleHulk (talk) 02:12, 4 September 2015 (UTC)


 * Psst... --71.119.131.184 (talk) 14:38, 4 September 2015 (UTC)


 * This is somewhat true in music and electronics: the really expensive guitars, mics, etc. tend to sound better than the middle-of-the-road, which almost always sound better than the really cheap stuff. Part of this is more expensive components (e.g. humbucker pickups in guitar), and part of it is build quality. This doesn't mean that you should just go out and buy the $2,000 Les Paul Classic: a $900 Studio model might sound just as good, especially with a custom nut and good pickups. However, you're not going to get a good sound out of the $199 Strats (or the plywood guitars hawked by Esteban or Keith Urban), no matter what you do. OldTimeNESter (talk) 12:54, 4 September 2015 (UTC)


 * Cars...the more you spend, the faster they go, the more comfortable they are and the more gadgets you get. On the other hand, the more they cost to buy, the more they cost to insure, the more they cost to repair and maintain, and the more gas they guzzle (in general).  So if your concern is "saving the planet", then a small car with high MPG is better than a luxury car with lower MPG...but if you're concerned about how comfortable you are when you drive, then more expensive is better.


 * The problem is that "better" is a subjective judgement and everyone measures it against a different set of criteria.


 * Someone suggested "wristwatch" as a counter-example because a cheap digital watch is more accurate than an expensive mechanical luxury watch...but accuracy is only one axis of the multi-dimensional "betterness" function. Some people buy luxury mechanical watches because they look nicer, or because they help the wearer to project an image as a wealthy person.  Some people like that they have an audible 'tick' and others just like to geek out on the amazing lengths the manufacturer went to in order to make them as accurate as they are.  "Better" doesn't mean "more accurate" it means "greater in some unspecified manner that dependent on the buyer".


 * So "better" is a tough term to nail down. If a more costly item was "worse" in every possible way than the cheaper one, why would anyone ever buy the costlier item?  Probably nobody would - the manufacturer would be forced to either drop that product line, reduce the price - or go out of business.  So we may conclude that these supposedly cheaper and better items are not "better" for absolutely everyone.  There has to be some market (albeit, perhaps a small one) where the cheaper item is seen as inferior in some way to the more expensive version.


 * SteveBaker (talk) 17:04, 4 September 2015 (UTC)


 * In an attempt to take the subjectivity out of the equation, it might be best to judge how long the item will last, based on it's price. Car tires (tyres to all you tea drinkers out there) are rated for mileage, so those would be convenient for comparison.  The pattern, as described previously, is that more expensive tires do tend to last longer, but not necessarily proportionately longer.  There are also speed ratings on tires, at least in the US, which affect price.  So, comparing tires with the same speed rating and manufacturer/retailer, you could graph out the cost versus mileage rating and get a good idea of the pattern.


 * I have often seen advertisers say something like "Our product may cost more than the competition, but it lasts longer, so it's a better value". However, when you do the math, you frequently find they charge 3 times as much for something that only lasts twice as long.


 * But, to return to your actual Q, you only asked for products which are better, not proportionately better, so that would be everything except the Veblen goods mentioned previously. That is, it is sufficiently rare to find a more expensive product which is inferior (aside from manufacturing defects, etc.) that we have a name and article for such goods.  Another category similar to Veblen goods, if we add the time element, is bleeding edge technology.  That is, you may well be able to buy the same thing, but better and cheaper, if you wait until the technology is perfected.  Similarly, a new fashion, etc., may be available for far less later, but wanting to be the first person in your city to buy it will cost you dearly.  So, in these two cases, the more expensive purchases are only "better" in that they are early, and not in any other measurable way.


 * I suppose we also need to include the category where something is more expensive, but is virtually identical to the cheap version. Bottled water often qualifies, in some cases just being tap water they put in a bottle.  And if you count chemicals that leach out of the plastic, the water quality can actually be worse than straight tap water.  Buying the same thing at different stores is another example, like your favorite brand of packaged food bought at Ralph's or Whole Paycheck.  They might even have the same batch number, yet you pay far more for the latter.    StuRat (talk) 17:17, 4 September 2015 (UTC)


 * Exactly. Why pay high for bad merchandise? There's no profit at either end. Wikiphotographers can provide examples of different ideas of good purchases and bad. My principal tools on the road are camera, bicycle, and mobile phone. The camera has an unusually high price for the small pixel count, which some might call a bad buy. For me, the GPS and wide angle performance are worth the extra money. The Brompton bicycle is much slower and heavier than sport bikes of similar price, but the extra money went for handiness in restaurants and trains, which better suits it to most jobs than my cheaper, faster Specialized Tri-Cross. The HTC cellphone is medium price, and clumsy when talking, but I don't need to talk; I need a computer. The processor is slow but the screen is big and bright. It works well for hunting for places that have a Wikipedia article and no photo, which is my main use for a computer on the road.


 * So yes, tools are diverse, even at similar price, because their purposes are diverse. Brompton bicycles and iPhones, besides being expensive tools, provide entry to a cult. Watches, besides telling the time, are jewelery. Are the sellers being evil, the buyers stupid because their cult prospers? Of course not, when they get what they paid for.


 * I would agree, except that deception is often part of the marketing strategy, making it look like their premium priced product can do things which it can't. (The Cadillac Cimarron ads sure didn't say it was just a more expensive Chevrolet Cavalier.) StuRat (talk) 18:42, 4 September 2015 (UTC)


 * Another point is that there may be a price below which it is not possible to produce a quality product and stay in business. So, at that price you can expect only shoddy merchandise (with possible exceptions where they sell at a loss, like going out of business sales).  However, at the high end, more expensive ingredients may not make the product any better.  For example, you can add gold dust to food, but it does nothing to improve the taste or nutrition. StuRat (talk) 20:10, 4 September 2015 (UTC)
 * Perhaps the most extreme example of a product that does become better as prices increase is money purchased from the bank. If you go to the bank, ask for a £50 note, and pay for it the normal way, you can be sure that it will serve the purpose of money (obtaining other objects that you desire) much "better" than will a similarly sized piece of paper that the bank will sell you for one-tenth the price.  Nyttend (talk) 22:37, 4 September 2015 (UTC)


 * The premise here is based on an equivocation between cost, price, and value. There's really not much to say, and a thread that starts out with "any thoughts?" is clearly an invitation to debate, and belongs elsewhere. μηδείς (talk) 03:27, 5 September 2015 (UTC)

Fundamentals of Engineering Examination without pre-requisites
According to Fundamentals of Engineering Examination, "The state of Michigan has no admission pre-requisites for the FE." So, can anyone in Michigan try his luck to become an engineer overnight? --YX-1000A (talk) 23:35, 3 September 2015 (UTC)
 * "The exam is open to anyone with a degree in engineering or a related field, or currently enrolled in the last year of an ABET-accredited engineering degree program" My other car is a cadr (talk) 03:28, 4 September 2015 (UTC)
 * Besides, completion of the FE exam is not the same as the completion of the PE exam. Roughly speaking, obtaining a passing grade on the FE exam only prepares one to take the PE exam something like five years later, after five years of engineering experience; that's the next step towards the goal of state licensure.  In some states, you can take the PE exam without ever having taken the FE exam, provided certain credentials and experience requirements are met.  Passing the FE exam, in itself, does not "make" you an engineer, and is certainly not sufficient for licensure.
 * All totalled up, this is kind of like the fact that in some states, you can pass the state bar exam and apply for admission without completing a JD degree. (Requirements in California, for example, permit certain categories of work experience in lieu of formal education).  The process does exist, but completing it is probably harder, more competitive, and more expensive than simply entering and completing law school.  The same goes for engineering licensure: how do you plan to pass an examination that tests the ensemble of knowledge accumulated over years of formal training, unless you have spent years informally educating yourself?  And even if you do pass, how will you find competitive employment suitable to meet the experience prerequisites for eventual licensure?  It could be done, but frankly, that sounds a lot harder than university.
 * Nimur (talk) 06:00, 4 September 2015 (UTC)
 * I've seen estimates of 14 years for a non degreed but capable person to get their PE. It would be much harder than being spoonfed through uni, and getting the necessary jobs would also be very difficult. Passing the FE starts the point at which your employment history counts towards your PE, and reputedly checks that you have some sort of engineering knowledge. The only bit of a PE test I've seen looked intellectually unchallenging and laborious, neither of which encouraged me to delve further. Greglocock (talk)