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December 2

Midget Jockeys

I'm looking for answers on why more midgets and dwarves aren't jockeys. They seem to have the right criteria due to their relatively small statute and weight. Yet, most jockeys appear to be normal statute people but at a very light weight.

By definition, dwarfs and midgets have underlying medical conditions. Maybe it's not obviously, but size is only a small part of what it takes to be a successful jockey. It's actually quite a challenging and demanding profession, Jockey has some info. Vespine (talk) 02:56, 2 December 2015 (UTC)[reply]

The jockey signals to the horse with pressure on it's flanks with his feet - that's going to be difficult for someone with very short legs. That said, in the sport of Camel racing, 4 year-old, half-starved children were used as jockeys until fairly recently (for the reason that they are lighter). Nowadays, they've been replaced by camel races that are run with Robot jockeys - radio controlled from SUV's driving alongside the track! SteveBaker (talk) 16:16, 2 December 2015 (UTC)[reply]

Our article jockey contradicts your assumption that jockeys are of normal stature: "Jockeys typically stand around 4 ft 10 in (1.47 m) to 5 ft 6 in (1.68 m)". Deli nk (talk) 16:24, 2 December 2015 (UTC)[reply]

That's not abnormal. —Tamfang (talk) 04:48, 4 December 2015 (UTC)[reply]

Mmmm...well...5'6" for a 30 year old white male is right on the 5% percentile...95% of men will be taller than him. 4'10" would be below the 1% percentile. The World Health Organization defines "abnormal" as being +/-2 standard deviations from the mean (5'10") - which corresponds to the 2.3% percentile - around 5'2". So it's quite clear that the height of some jockeys is "abnormal" and for others it is "normal" - most of them are hovering right on the edge of "normality". SteveBaker (talk) 03:53, 5 December 2015 (UTC)[reply]

Universe is infinitely old??

If the universe is infinitely old, then can anyone be more specific on what happened more than 20 * 10^9 years ago?? Georgia guy (talk) 00:25, 2 December 2015 (UTC)[reply]

(Unproductive "infinite past is impossible" subthreads collapsed. -- BenRG (talk) 06:44, 2 December 2015 (UTC))[reply]

Extended content

It's mathematically impossible for the universe to be "infinitely" old. ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:27, 2 December 2015 (UTC)[reply]

It is absolutely not "mathematically" impossible for the universe to be infinitely old. I was under the impression that it was impossible in a more contingent sense (that is, we have sufficient evidence to assert that it is not infinitely old). But there's nothing whatsoever mathematically wrong with the idea of an infinitely old universe, and if they taught you otherwise in seventh grade, then you were mistaught. --Trovatore (talk) 00:38, 2 December 2015 (UTC)[reply]

No, what they taught us is that there is no point in any measurement system that equates to infinity. If the universe were infinitely old, we would be at such a point. No. It doesn't work. ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:42, 2 December 2015 (UTC)[reply]

Not true. If, for any natural number N, there was an event at least N seconds in the past, then the universe is infinitely old. There is nothing wrong with this mathematically.

Now, what is true is that, if the universe is infinitely old, then you can't use "seconds since the beginning of the universe" as a time scale. That seems to be roughly your line of reasoning here. That's true, but how do you know you can use that as a time scale? There may be ways you can know it, but not "mathematically"; the mathematics works just fine.

Note that if the universe is currently infinitely old, then it always has been infinitely old. (Well, in the simplest case anyway; we can hypothesize more exotic possibilities where this wouldn't be true, but that's the most natural possibility.) --Trovatore (talk) 00:58, 2 December 2015 (UTC)[reply]

No. It doesn't work. Time does not go backward N or N+1, it only goes forward. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:06, 2 December 2015 (UTC)[reply]

Hmm? How do you know this, exactly? As I say, I don't exclude that there's some way to know it, but it isn't "mathematically". The mathematics of an infinitely old universe is just fine. --Trovatore (talk) 01:07, 2 December 2015 (UTC)[reply]

It's not fine. It doesn't work. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:09, 2 December 2015 (UTC)[reply]

Doesn't work how? --Trovatore (talk) 01:12, 2 December 2015 (UTC)`[reply]

Look near the bottom of the Age of the universe article. Georgia guy (talk) 00:28, 2 December 2015 (UTC)[reply]

I see. And they're wrong. They need to go back to seventh grade math class and learn what "infinity" means. ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:33, 2 December 2015 (UTC)[reply]

You can use your own judgement here on whether to accept Baseball Bugs's say-so as a measure of mathematical possibility and impossibility. --Amble (talk) 00:37, 2 December 2015 (UTC)[reply]

It's not known to be infinitely old. See age of the universe for a current best value of 13.799±0.021 × 10⁹ years. We don't know what, if anything, was before that, or whether there was a before that. There are some specific models that let you say something about times before the Big Bang, although they aren't consistent with one another and aren't known to be correct. Are you looking for information about what came before the Big Bang in various models that have such a thing? --Amble (talk) 00:37, 2 December 2015 (UTC)[reply]

The operative word there is "if it turns out to be true"...I'm not sure if that even deserves a footnote in our article. Alternative models can be a dime a dozen, it doesn't mean they present any real challenge to the current model, and the "press release" used as a reference gives no indication if anyone at all is taking this seriously academically. I disagree with bugs though, I don't think it's fundamentally impossible for the universe to have no beginning. Maybe there was a big bang and maybe there was a universe before the big bang, maybe there's a string of big bangs going back into the past without a beginning. How is that not an infinitely old universe? or if you don't like universe then infinitely old "cosmology"? Saying that the universe fundamentally "can't" be infinitely old seems to me just as nonsensical as saying the universe CAN'T have a beginning, because what came before it? and saying "time it self begun with the universe" sounds a lot like special pleading. Vespine (talk) 00:42, 2 December 2015 (UTC)[reply]

Extended content

It is not possible to know what, if anything, came "before" the Big Bang. But the Big Bang is a starting point. An infinity has to have a starting point. Otherwise it makes no mathematical sense. ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:45, 2 December 2015 (UTC)[reply]

What's the "starting point" of the real numbers? --Trovatore (talk) 01:03, 2 December 2015 (UTC)[reply]

Zero. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:09, 2 December 2015 (UTC)[reply]

I mean, left to right, left being negative, what's the starting point? −1 is to the left of 0, so 0 can't be the starting point in that sense. --Trovatore (talk) 01:11, 2 December 2015 (UTC)[reply]

Zero aka the "origin" point, is the starting point. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:38, 2 December 2015 (UTC)[reply]

"An infinity has to have a starting point, otherwise it makes no mathematical sense". Source please? You realize that "mathematics" is not "reality"? It's a tool we've invented, it wouldn't be anywhere near the 1st time something that "didn't make mathematical sense" turned out to be true. Until we invent the mathematics to go along with it, like imaginary numbers, or even zero. Vespine (talk) 00:55, 2 December 2015 (UTC)[reply]

Oh, I dispute the claim that mathematics is not reality. But that's a side issue. --Trovatore (talk) 00:59, 2 December 2015 (UTC)[reply]

And before this turns into a "debate", I'm not claiming to KNOW the answer, I'm pointing out that people like Bugs, who come here and proclaim definitive answers don't know EITHER. There is genuine debate between actual scholars in relevant fields regarding these subjects. When someone like Bugs just comes here and proclaims "it's impossible for the universe to be infinitely old" and anyone who claims otherwise is just plain wrong, THAT'S what I have an issue with. Vespine (talk) 01:00, 2 December 2015 (UTC)[reply]

The notion of the universe being "infinitely" old does not work. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:04, 2 December 2015 (UTC)[reply]

The notion of the universe being "infinitely" old does not work. Are you actually trolling at this point? Vespine (talk) 01:12, 2 December 2015 (UTC)[reply]

This is a point where people often misunderstand what actually is standard in cosmology. The Big Bang cosmology describes the history of the universe from very early times, but it doesn't claim to describe the beginning itself. You can say that the Big Bang Theory is a model of everything that has ever happened in the history of the universe except for the Big Bang. Various extensions to the Big Bang model try to fill in this gap. Some (like Hawking's pea instanton) have a beginning, and some (like eternal inflation) don't. It's hard to say that either one is really a standard or an alternative; instead, both options are consistent with the standard cosmology. What we do know for sure is that our universe hasn't been around forever in its present form; we know that all steady state theories are incorrect. --Amble (talk) 01:04, 2 December 2015 (UTC)[reply]

Extended content

All models of eternal inflation produce a hypothetically infinite multiverse. Hey Bugs, can you contact Alan Guth and tell him he's wasting his time? You've obviously got it all worked out. ;) Vespine (talk) 01:25, 2 December 2015 (UTC)[reply]

"Eternal inflation" has to start somewhere. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:29, 2 December 2015 (UTC)[reply]

Why? --Trovatore (talk) 01:32, 2 December 2015 (UTC)[reply]

How else could it work? ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:39, 2 December 2015 (UTC)[reply]

Time could be like the real numbers, which have no starting point. Zero is not the "starting point" of the real numbers in the relevant sense. --Trovatore (talk) 01:43, 2 December 2015 (UTC)[reply]

Zero is the "origin point" in math coordinate systems. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:47, 2 December 2015 (UTC)[reply]

Sure, but that's a different sense of the word "origin". It doesn't mean it's the starting point from left to right (where right is the direction in which numbers increase). Mathematically speaking, time could be like the real numbers, where the zero point is just any arbitrary moment, and there are events arbitrarily long times both before and after that moment. If that is so, then the universe is infinitely old.

No one needs to bother pointing out that I haven't taken relativity into account here. Of course I haven't. I'm not talking about known physics. We're just discussing what is "mathematically" possible. --Trovatore (talk) 01:55, 2 December 2015 (UTC)[reply]

And right now T = 0. lol. Vespine (talk) 01:56, 2 December 2015 (UTC)[reply]

I have a problem with the way this thread is progressing. Bugs: this is NOT a forum for you to debate your opinions, it's gone on too long. Please support your claims with references or just stop posting, this is a REFERENCE desk, "not a debate your opinions desk". Vespine (talk) 02:05, 2 December 2015 (UTC)[reply]

I'm not sure "time" as a construct is useful at the very origin of the universe. Time isn't constant and likely folds into other elements that are not what we would call "time." As an aside (with the question kind of implied in the article), if I recall fractal representations of the coast of Greenland is an unbounded sum and the length of the coast of Greenland is mathematically infinite. It's not asymptotic but the growth slows but it doesn't stop. The concept of infinite is not simple nor regular and the assumption that infinite mathematical subdivision is physically possible is not at all clear. There may be fundamental "feature sizes" that limit further subdivision. The time it takes light to travel the Planck length may be the limit to which time can be subdivided (and might be quite a bit longer before time even manifests itself as time as we know it. --DHeyward (talk) 03:22, 2 December 2015 (UTC)[reply]

One hugely important take-home message from relativity is that time is not an absolute thing. The passage of time is different for different observers - time seems to go very rapidly for objects moving very fast - and for objects that are very dense. Inside a black hole there is believed to be a "singularity" (a point of zero size and infinite density) - and passage of time at that point happens infinitely fast. So from the point of view of the singularity itself...how long has it existed? It becomes a meaningless question. From the perspective of an outside observer - we can (in principle) tell when the black hole formed - and know it's age as a definite, entirely finite, quantity. However, that doesn't allow us to say: "That's the age of the black hole" when 'within' the black hole itself. It's age depends entirely on where you're looking at it from.

If (as seems possible - perhaps even likely) the universe as we know it started as a 'singularity' (rather like a black hole) then an outside observer could hypothetically tell us how old it is - but there are no outside observers - by definition, all of everything is inside the singularity - including everything that you and I came from. So from our perspective, if the universe was ever a literal singularity - then there is no meaningful answer as to how old it is because at the outset, the passage of time was infinitely fast.

So it ends up depending on who is observing the universe and measuring the time - and for us, it's a meaningless question.

Of course (as others have explained) the Big Bang theory only tells us what happened after the big bang started - presumably because all of those infinities would prevent us from knowing anything about that pesky singularity. It's possible that the universe somehow started up in a way that made it very, very small indeed - but not a singularity - in which case there might well be an answer about its age - and it might actually be finite - and there might well be a "before".

But if we started in a singularity - then there is no meaningful answer - and "infinity" is a pretty good choice. The problem with that is the idea that an infinite amount of time passed - and then the big bang happened...which is just as hard to get your head around.

SteveBaker (talk) 15:55, 2 December 2015 (UTC)[reply]

Bugs's hatted comments above are correct. There are no actual infinities, only potential ones, for which see actual infinity and http://plato.stanford.edu/entries/aristotle-mathematics/. The bottom line is that an "infinitely old" universe could have no actual age, because however old it actually was, it would have to be even older than that. μηδείς (talk) 16:44, 2 December 2015 (UTC)[reply]
The position that there are no actual infinities is certainly one that used to be held by almost all scholars, but that was a long time ago. Through the work of Georg Cantor and others it has become clear that the concept of actual infinity is very useful. Whether it corresponds to any underlying reality is controversial, but your position that it does not is also controversial.

It's true that an infinitely old universe would not have an age that is a real number. So what? As time progressed, its age would stay the same. So what? Can you show that it is somehow logically necessary that the universe must have an age that is a real number, or that its age must increase with passing time? --Trovatore (talk) 18:45, 2 December 2015 (UTC)[reply]
Has the universe "always" been expanding? ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:56, 2 December 2015 (UTC)[reply]
Ah, now you're getting into physics. Your claim was that an infinitely old universe was "mathematically" impossible. We may know (contingently) that it isn't true that the universe is a steady state, but that's physics-based knowledge, not mathematics. --Trovatore (talk) 19:59, 2 December 2015 (UTC)[reply]
Who said the universe is a steady-state? I say it can't be infinitely old because there would have to be an infinity of points in time behind us, which means we would have to have reached infinity - which we haven't. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:02, 2 December 2015 (UTC)[reply]
No one (here) said it's a steady state. The point is, your comment about expansion implicitly assumes that expansion happens. We know expansion happens — but we know it from physics, not mathematics. Therefore it has no bearing on what's mathematically possible.

As for your second sentence, the real number 0 has infinitely many points before it, and yet 0 is not ∞. --Trovatore (talk) 21:46, 2 December 2015 (UTC)[reply]

I don't know why, but apparently Bugs is on a bender of posting weird claims about math on physics questions and then arguing with people who correct the misinformation. While arguments can occur and do (and sometimes should!) occur here, they should also be approached in good faith with a willingness to learn, and rest upon referenced information. As it stands now I think Bugs' recent behavior is very close to trolling, so I'd recommend a prescription of WP:DNFTT. SemanticMantis (talk) 21:55, 2 December 2015 (UTC)[reply]

I'm really not that interested in convincing Bugs. What tasks me, as Khan might have said, is that I have failed to explain myself to Medeis. That I don't understand at all. --Trovatore (talk) 22:46, 2 December 2015 (UTC)[reply]

It might tell you something, as Medeis is pretty smart. But you're not nearly as dumb as I am, which must be why I don't understand your explanations. They contradict the math I was taught, and I typically scored well in math. So if I'm wrong, I need more info, directly from you, and in a way that my feeble mind can understand. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:56, 2 December 2015 (UTC)[reply]

Hmm. You could help me out by letting me know where is the disconnect when I say that time could be (not "is", just mathematically "could be") like the real numbers. I assume you're familiar with the picture of the real numbers as a line, extending infinitely far both to the left and to the right of any fixed point (such as the number zero)? What are you getting stuck on, when I say there's no mathematical reason that time couldn't look like that, with "left" identified with "the direction against the time arrow", and that that would make the universe infinitely old? --Trovatore (talk) 23:00, 2 December 2015 (UTC)[reply]

Time goes forward, not backward. But let's try this... A few weeks back, there was a vaguely similar discussion about the universe expanding, with an analogy being made to a rubber band, and then a rubber sheet, with dots on it representing galaxies. As the galaxies expand, the rubber band or sheet stretch, and you can't discern any "central point" because everything is expanding. But consider this, which is the only way I've come up with so far: consider 2 galaxies, A and B. Let's say they are currently 8 billion light years apart and receding from each other. Looking backward in time, it stands to reason that at some point in time they would have been only 4 billion light years apart. The total time elapsed between the 8 and the 4 points, let's call T1. At some point further back, they would be only 2 billion light years apart. The total time elapsed between the 4 and 2 points, let's call T2. And so on. I'm aware that T1, T2 and so on might not be conventionally "uniform" compared to each other. But I'm assuming that as the distance continues to halve, the time continues to "approximately" halve as well - until you get to, or near, a point where galaxies A and B are next to each other. If each time interval is (approximately) halved, theoretically you never get to 0... except that the distance also continues to halve - hence, Xeno's paradox hence, I still don't get how it works. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:30, 2 December 2015 (UTC)[reply]

Hold on, are we discussing physics now? You said it was "mathematically" impossible for the universe to be infinitely old, and your subsequent comments gave me the impression that you thought this was true independent of any reliance on modern physics (such as galaxies moving apart). If I misunderstood (or if you've changed your mind as to what you're interested in) then that's a completely different discussion. I've been addressing only whether it makes sense mathematically. --Trovatore (talk) 23:46, 2 December 2015 (UTC)[reply]

I don't know why, but apparently you're on a bender of posting non-answers to valid questions I've raised. Maybe you're the troll. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:39, 2 December 2015 (UTC)[reply]

Guys... all of this philosophical stuff is pointless because it fundamentally comes from a position of ignorance. There's a lot of circumstantial evidence that the continuum picture of spacetime breaks down in quantum gravity. One of the foundational ideas of loop quantum gravity is that field lines are quantized and, once you mod out the GR gauge group, only their discrete braiding structure is physically relevant. The Bekenstein entropy bound suggests that the physics in a finite region has finitely many degrees of freedom. A fundamentally discrete, countable physics could correspond to an infinite past in some classical approximation. We don't know. Nobody knows, but at least some people are making an honest effort to figure out what the available evidence seems to say about the nature of the world instead of spouting off philosophical insights that boil down to a pre-rational evolved intuition for geometry at length scales that are relevant to our survival. Aristotle didn't even figure out Newton's laws of motion, and you are not smarter than Aristotle. So shut up. -- BenRG (talk) 23:26, 2 December 2015 (UTC)[reply]

One is tempted to refer the Right Honourable Members to 0.999... for possible edification. Tevildo (talk) 21:04, 2 December 2015 (UTC)[reply]

@Trovatore: I saw your comment above, and assuming you weren't just teasing My Esteemed Colleague from the WB, I'll make a few comments. First, I am familiar with Cantor, and realize that theoretically one can do all sorts of infinite things with finite objects, as with the Cantor set. My problem with declarations that the universe is infinite in space or time is that either the statement is meaningless and/or contradictory, or that there may be some meaning there, but it hasn't been rigourously expressed in a way that is meaningful or open to challenge.

Also, I make no universal negative claim. All knowledge is bounded by horizons, the light cone, the cosmic background radiation, the Planck limit and Heisenberg uncertainty principle. I'll gladly accept that we cannot tell, with the given state of knowledge and technology, and indeed may never be able to tell if or what causal factors may have been prior to the big bang. Perhaps our knowledge is naive now in the way that it was when astronomers thought that all that existed was our own galaxy, and the nature of spiral nebulas as other galaxies along time ago and far far away was unexpected.

Basically, the only a priori position I am willing to take is that cosmology is not in the realm of philosophy, that non-scientific speculation is suspect, and that suppositions that are contradictory or unclear don't merit extended comment. μηδείς (talk) 01:07, 3 December 2015 (UTC)[reply]

This sounds somewhat different from your earlier comments, where you asserted affirmatively (for example) that "there are no actual infinities". Is that not a "universal negative claim"?

In any case, if you want me to be more specific and rigorous about what a spatially or temporally infinite universe would mean, I can do that. That would hopefully take it out of the realm of "unclear". As for "contradictory", you could then attempt to find an actual self-contradiction, if you still maintain that the notion is self-contradictory (it's not clear in your latest comments whether you do or do not). --Trovatore (talk) 02:18, 3 December 2015 (UTC)[reply]

That this might sound different is why I clarified myself, User:Trovatore. Basically, my opinion is OR, not RS. So I will sign off with the clarification that "there are no actual infinities" is a double negative. It means that every thing that is actual is limited (has a defined nature); to be is to be a certain something. To deny this is to make an undefined claim. μηδείς (talk) 01:37, 4 December 2015 (UTC).[reply]

Ah, I see, thanks for clarifying. To me this sounds like what you are denying is not so much actual infinity as actual absolute infinity. Infinity (but arguably not absolute infinity) can in fact be limited, have a defined nature, and be a certain something.

The test for whether something is infinite, as the word is understood today, is that it is bigger than any natural number. So if, for example, for every natural number N, there are points further apart than N miles, then the universe is spatially infinite. That does not make the universe fail to have a defined nature or fail to be a certain something, it just makes it bigger than any natural number of miles.

Interestingly, as I understand it, Cantor understood the word "infinite" much as you do, and this is why he referred to his new numbers as transfinite rather than infinite. They were not infinite, meaning without limit, but they were transfinite; they were beyond some limit (for example the limit ordinal ω, though I don't know if he conceived of it in those terms when he coined the word). Be warned that this is somewhat folklore; I don't have a source for this motivation of Cantor's.

In any case, this scruple of Cantor's, if such it was, is not generally shared today. If that is the sense of "infinite" that you mean, it would probably be better to clarify that up front. --Trovatore (talk) 04:00, 4 December 2015 (UTC)[reply]

Ah, I thought of a neater way of putting it. Suppose, for any point off in the distance, no matter how far away it is from you, there is another point that is at least one mile farther from you than the first point. Then the universe is spatially infinite.

Suppose, for any event, no matter how long ago it was, there was another event that preceded that event by at least one second. Then the universe is infinitely old.

I hope these formulations clarify what I mean by "infinite". I'm going to anticipate an objection that this is potential infinity rather than actual infinity. The potential-v-actual distinction here doesn't reside in the notion of "infinity", but in the notion of "universe". If you accept that there is such a thing as the universe, considered as a completed totality, then the criteria given would make it actually infinite, not just potentially. --Trovatore (talk) 08:19, 4 December 2015 (UTC)[reply]

Boxelder bug or Small Milkweed bug?

This picture appears in the Boxelder bug (Boisea trivittata) article. An IP editor recently changed the caption to say that they are Small Milkweed Bugs (Lygaeus kalmii). I am inclined to ask Commons to change the image name because the current one is highly misleading if that is true. Can anyone confirm the correct identity of these bugs? SpinningSpark 10:23, 2 December 2015 (UTC)[reply]

Based on http://www.unexco.com/box-milk.jpg (referenced from http://www.unexco.com/boxelder.html), they are clearly milkweed bugs. Looie496 (talk) 12:15, 2 December 2015 (UTC)[reply]

Transportation industries

Are all transportation industries including highway, railway, airline etc all very complex industries? 2A02:C7D:B901:CC00:C16C:F21B:AD37:1EBA (talk) 18:46, 2 December 2015 (UTC)[reply]

See Transportation: the very, very first (16 January 2001) Wikipedia article! In short, no. One can run a transportation company with one van and one driver. Tevildo (talk) 19:13, 2 December 2015 (UTC)[reply]

However, the OP was asking about industries, not companies. {The poster formerly known as 87.81.230.195} 185.74.232.130 (talk) 14:13, 3 December 2015 (UTC)[reply]

Logistics however can be a VERY complicated thing. --Jayron 32 21:36, 2 December 2015 (UTC)[reply]

If logistics is complex, I'm assuming transportation industries are too? Since they are very similar. 2A02:C7D:B901:CC00:E5EE:75C:A910:D365 (talk) 22:32, 3 December 2015 (UTC)[reply]

Replacing a fuse of a microwave grill oven

My beloved relatively ancient microwave oven with grill has lost its grill function after a day of heavy use. The microwave modus works as well as previously. I suspect this is just a blown fuse, which is specific to the grill, and wonder how easy it is to replace it. If I open the case, would be fuse be easily visible, accessible and replaceable? Can the cause be something completely different? --Kiwipidean (talk) 21:50, 2 December 2015 (UTC)[reply]

Yes, fuses are often fairly easy to replace. Other causes sadly are a break anywhere in the entire circuit, eg controller, or the grill element itself. Given the spectacularly lethal voltages inside a microwave I'd be a bit hesitant about opening one up if you haven't done that sort of thing before, but I guess in kiwiland it may be a long drive to a skilled repairdroid. You may find a service manual online, eg http://www.hobbielektronika.hu/forum/getfile.php?id=191466 Greglocock (talk) 22:47, 2 December 2015 (UTC)[reply]

Do NOT repair your microwave oven yourself. Do NOT open the case. Older style microwave ovens contain capacitors that can retain high voltage and lethal energy for considerable time after they are switched off and unplugged. There are specific safety procedures listed in service tech training and in service manuals, but I am not going to describe them here. Newer style "inverter" microwave ovens are a lot safer in this respect, but non-qualified persons are still best advised to not attempt repair. If you need to ask a question like this, you are clearly not qualified to carry out repair safely. Qualified servicemen also have instruments to check RF leakage and ensure that is safe. It should not be difficult to find a serviceman or repair shop in New Zealand. Recent articles and letters in trade journals indicate than many are struggling to get enough customers through the door but they are still around. 124.178.37.23 (talk) 02:10, 3 December 2015 (UTC)[reply]

And how would an RF leakage detector help with identifying whether HV is present? Oh that's right, it wouldn't in the slightest. Not all of us have a handy repairdroid. Greglocock (talk) 04:04, 3 December 2015 (UTC)[reply]

Nobody said it did. In fact I strongly implied it didn't - did you see the word "also" in my answer? The thing is, old microwaves can develop door seal deterioration or latch wear that allows leakage. Not common, but it does occur. When old microwaves come to a serviceman for attention, it won't be because of RF leakage. The owners never know. But the servicemen can check it and correct it as necessary. A 2nd benefit of taking it to a qualified serviceman. 124.178.37.23 (talk) 05:27, 3 December 2015 (UTC)[reply]

If you are thinking about attempting a repair, I would suggest trying to obtain a service manual for the thing. It would not only address necessary cautions but also answer your original question. Sometimes service manuals can be found on the Internet. Just make sure, if you find one, that it is for the correct model. --76.69.45.64 (talk) 04:55, 3 December 2015 (UTC)[reply]

This is a bit like thinking you can do surgery just because you have a textbook on surgery. You can't. Medical textbooks are written assuming the doctor has appropriate training, and electronics service manuals are written on the assuption that the tech has appropriate training. If your knowlege of electronics is at the level of the OP's, it's not safe for you to work on it, with or without the manual. It isn't 115V or 230V inside. It's kilovolts. One stray finger and quite possibly you've had it. 124.178.37.23 (talk) 05:27, 3 December 2015 (UTC)[reply]

In any case, fuses can occaisonally blow due to fatigue. But mostly they blow for a reason. A good serviceman will ask himself "why did it blow?" and locate and correct the cause. All of us in the electronics game for a reasonable time have had to advise an owner that their appliance has to be written off because the fool has through ignorance or deliberate action replaced a fuse with the wrong type or rating, thereby allowing extensive damage to occur. And if that caused a fire, insurance companies won't cover it. 124.178.37.23 (talk) 05:27, 3 December 2015 (UTC)[reply]

Replacing the fuse with an identical rated fuse is a good test. If that one quickly burns out, too, then there probably is a problem. If not, then the first fuse likely just failed from age. StuRat (talk) 05:44, 3 December 2015 (UTC)[reply]

Not really. The trouble lies within what is "quickly". Immediately? After a couple of hours use? After a week? A month? All these mean a definite fault. Faults can be "hard on" or intermittent. And there is still the extreme safety hazard of a non technical user poking around in a circuit where there can be kilovolt lethal stored charge. And you haven't addressed the problem that an unqualified user may cause further circuit damage and/or a fire hazard by unintentionally fitting a fuse of the wrong type. I've seen people put in a 10 amp fuse where a 1.0 Amp fuse should go - very dangerous. Or a delay fuse where a fast blow fuse should go - they look the same to an unqualified user. Fuses don't fail due to age anyway. They do occaisonally fail due to fatigue. Not the same thing. Due to the very short on-time per day of typical microwave oven use, coupled with often only a single on-off cycle per day, fuse fatigue is someting I would be quite reluctant to accept. 124.178.37.23 (talk) 10:20, 3 December 2015 (UTC)[reply]

I have a workaround for you. There is a microwave absorbing foil you can get, to place beneath the food in the microwave, which will provide heating from the bottom. Many frozen microwaveable foods have such foil to provide browning. With this you can continue to use the microwave, without hauling it off to a repair shop or risking electrocution. StuRat (talk) 02:26, 3 December 2015 (UTC)[reply]

Do we have an article about that material? I know what you're talking about, just seems like an actually known-by-the-public item that should be here on WP...somewhere... DMacks (talk) 07:27, 3 December 2015 (UTC)[reply]

Didn't find it, but when looking I found this product, a microwave grill pan, which apparently absorbs microwaves and puts grill lines on the bottom of your food with the heat generated: [1]. 07:40, 3 December 2015 (UTC)

Finally found susceptor (and made it more easily, found via microwave susceptor). DMacks (talk) 07:42, 3 December 2015 (UTC)[reply]

Careful if not trained service person, avoid to do it yourself! You need to have minimum of needed skills to work save with HV and RF components. In the microwave part, a high voltage fuse is installed. In the oven heater circuit, a thermal fuse or thermostat and a fuse is installed. Toasters use sheet mica in the heater unit. Only replace identical spare parts with identical values! Improper work or opening the device can cause shortcut, fire, exploding parts, electric hazard, microwave exposure causing irreversible injuries. --Hans Haase (有问题吗) 23:54, 4 December 2015 (UTC)[reply]