# Painful confession time: Things you \*ought\* to know but \*don't\* **URL:** \ **Category:** In My Humble Opinion\ **Created:** [April 30, 2010, 6:12am UTC](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836 "2010-04-30T06:12:48Z")\ **Posts on this page:** 20\ **Page:** 7
**Author:** ![Sitnam](https://avatars.discourse-cdn.com/v4/letter/s/6a8cbe/32.png) [@Sitnam](https://boards.straightdope.com/u/Sitnam)\ **Post date:** [May 16, 2010, 3:05pm UTC](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836/121 "2010-05-16T15:05:17Z")
Having not significantly used my BS Math degree in the last 5 years I’ve forgotten an embarrassing amount of stuff I really should know. ---
**Author:** ![Cardinal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cardinal/32/4000_2.png) [@Cardinal](https://boards.straightdope.com/u/Cardinal)\ **Post date:** [May 16, 2010, 5:20pm UTC](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836/122 "2010-05-16T17:20:56Z")
> [@Koxinga](#): > > I know what the number is, but how do you “multiply” matter by this or any other number? I’ve never gotten that either. Well, I don’t think there’s much to say except that in physics or chemistry we often multiply matter (kg) by other things. A Joule is the energy used to push 1 kg for 1 second such that it accelerates at 1 meter per second squared. So if the object was going 4 m/s, and I use one second to push on it and at the end it’s going 5 m/s, I’ve used one Joule, or (and here’s the big point) 1 kg\*m2 / s2. Those 2s are “squared”, I can’t figure out at all how to make them superscript. And this is of course using the textbook unreal situation of a frictionless environment, if you care to know. An easier one that you’ve used many times is speed. Realize that for the result to be miles per hour, you must have taken miles (distance) and divided it by hours (time), which is pretty much what you’re talking about. So everyone does this kind of thing every day. ---
**Author:** ![katie1341](https://avatars.discourse-cdn.com/v4/letter/k/91b2a8/32.png) [@katie1341](https://boards.straightdope.com/u/katie1341)\ **Post date:** [May 16, 2010, 6:47pm UTC](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836/123 "2010-05-16T18:47:58Z")
> [@CanvasShoes](#): > > Lay vs. Lie. I read the rule, THINK I’ve got it down, and then when it’s time to use one or the other, have no clue which one is required. Grrrrrrrrr… Lay = place, as in to place something somewhere. “Just lay that down anywhere”. Lie = recline. “I’m going to go lie down”. That’s how I remember them. ---
**Author:** ![nuggz](https://avatars.discourse-cdn.com/v4/letter/n/278dde/32.png) [@nuggz](https://boards.straightdope.com/u/nuggz)\ **Post date:** [May 16, 2010, 9:45pm UTC](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836/124 "2010-05-16T21:45:15Z")
The main difference with people is that there are people who know they don’t know stuff, and there are people who think they know everything. I know nothing. ---
**Author:** ![Sitnam](https://avatars.discourse-cdn.com/v4/letter/s/6a8cbe/32.png) [@Sitnam](https://boards.straightdope.com/u/Sitnam)\ **Post date:** [May 17, 2010, 12:36am UTC](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836/125 "2010-05-17T00:36:23Z")
> [@nuggz](#): > > The main difference with people is that there are people who know they don’t know stuff, and there are people who think they know everything. > > I know nothing. Despite Billy Shakespeare et al.'s pithy phrases this doesn’t make you wise. ---
**Author:** ![notsoheavyd3](https://avatars.discourse-cdn.com/v4/letter/n/85e7bf/32.png) [@notsoheavyd3](https://boards.straightdope.com/u/notsoheavyd3)\ **Post date:** [May 17, 2010, 1:23am UTC](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836/126 "2010-05-17T01:23:59Z")
What do I not know how to do that I should know? After thinking a bit I’ve got a good one. I don’t know how to sound out words. Seriously, I can kind of fake it but I’m really no good at it.(Which would probably surprise alot of people who know me since I actually did well in school until college.) Too be fair though, I taught myself to read before kindergarten and I basically learned to just memorize what pronounciations went with what words. (They skipped that skill in 1st grade with me because they probably figured I already knew how.) Also I’m talking about english of course and lets be honest, way too many words are not pronounced they way they’re spelled so I’m not missing out much.🙂 ---
**Author:** ![Yumblie](https://avatars.discourse-cdn.com/v4/letter/y/76d3ee/32.png) [@Yumblie](https://boards.straightdope.com/u/Yumblie)\ **Post date:** [May 17, 2010, 2:04am UTC](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836/127 "2010-05-17T02:04:31Z")
> [@A\_Dodgy\_Dude](#): > > Also, e=mc²… “the speed of light squared” … I have no idea what that means. If you’re a physicist this is something you ought to know, but is there a reason that it’s embarrassing that you don’t know what this equation means? There’s lots of stuff in fields outside my own that I wish I knew but I can’t really say I _ought_ to know. It’s not like e=mc^2 is part of a typical elementary school curriculum. As a physics grad student, I can’t make heads or tails of circuits. I can solve simple book problems, but place a real electronic circuit in front of me and ask me to fix it or analyze it, then you might as well be asking someone from the middle ages. ---
**Author:** ![Koxinga](https://avatars.discourse-cdn.com/v4/letter/k/4af34b/32.png) [@Koxinga](https://boards.straightdope.com/u/Koxinga)\ **Post date:** [May 17, 2010, 2:19am UTC](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836/128 "2010-05-17T02:19:39Z")
> [@Cardinal](#): > > Well, I don’t think there’s much to say except that in physics or chemistry we often multiply matter (kg) by other things. > > A Joule is the energy used to push 1 kg for 1 second such that it accelerates at 1 meter per second squared. So if the object was going 4 m/s, and I use one second to push on it and at the end it’s going 5 m/s, I’ve used one Joule, or (and here’s the big point) 1 kg\*m2 / s2. Those 2s are “squared”, I can’t figure out at all how to make them superscript. And this is of course using the textbook unreal situation of a frictionless environment, if you care to know. ehhh . . . still don’t get it. OK, imagine I wanted to express how much energy was in the pencil that I’m holding here. Could you help me fill in the blank? “If I take this pencil and \_\_\_\_\_ it by 186,000^2 times, then it will yield [so much] energy.” What is “\_\_\_\_”? Please don’t say “multiply”, that will just give me a really large quantity of pencils. ---
**Author:** ![Yumblie](https://avatars.discourse-cdn.com/v4/letter/y/76d3ee/32.png) [@Yumblie](https://boards.straightdope.com/u/Yumblie)\ **Post date:** [May 17, 2010, 2:50am UTC](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836/129 "2010-05-17T02:50:30Z")
> [@Koxinga](#): > > ehhh . . . still don’t get it. > > OK, imagine I wanted to express how much energy was in the pencil that I’m holding here. Could you help me fill in the blank? > > “If I take this pencil and \_\_\_\_\_ it by 186,000^2 times, then it will yield [so much] energy.” > > What is “\_\_\_\_”? Please don’t say “multiply”, that will just give me a really large quantity of pencils. You don’t multiply the number of pencils, you multiply its mass. You might be overthinking it, as I’m not sure what the huge conceptual leap is. Take for example momentum. Thinking of it intuitively, imagine being hit by a baseball going at some speed. Now imagine being hit by a baseball at double that speed. It’s gonna hurt more, right? You’ll feel more momentum as it hits you, in fact twice as much momentum. Now imagine being hit by a baseball at the original speed, but the baseball weighs twice as much. You’ll again feel twice the amount of momentum as before. To summarize, the momentum you feel is: _p = mv_ where _m_ is the mass of the object hitting you and _v_ is the speed. If you want to know how much momentum a baseball is going to have, all you need is the speed it’s going at and its mass. You don’t multiply the baseball by anything because that’s nonsensical, a baseball’s an object, not a number. Nature doesn’t care what the object is, it just deals with numbers. This is the same idea. If you converted a pencil that has a mass _m_ into pure energy, the amount of energy will be _mc_[sup]2[/sup]. Any object with the same mass will give you that same energy, whether it’s a pencil or 50 paperclips or whatever. ---
**Author:** ![Koxinga](https://avatars.discourse-cdn.com/v4/letter/k/4af34b/32.png) [@Koxinga](https://boards.straightdope.com/u/Koxinga)\ **Post date:** [May 17, 2010, 3:26am UTC](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836/130 "2010-05-17T03:26:03Z")
> [@Yumblie](#): > > This is the same idea. If you converted a pencil that has a mass _m_ into pure energy, the amount of energy will be _mc_[sup]2[/sup]. Any object with the same mass will give you that same energy, whether it’s a pencil or 50 paperclips or whatever. Fine, I was being a bit whimsical with the pencil thing, but to be more [del]pedantic[/del] specific: “If I take **the mass contained within** this pencil and \_\_\_\_\_ it by 186,000^2 times, then it will yield [so much] energy.” Once again, what fills in that blank? “accelerate?” “motivate?” “rejuvinate?” ---
**Author:** ![Yumblie](https://avatars.discourse-cdn.com/v4/letter/y/76d3ee/32.png) [@Yumblie](https://boards.straightdope.com/u/Yumblie)\ **Post date:** [May 17, 2010, 5:06am UTC](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836/131 "2010-05-17T05:06:53Z")
> [@Koxinga](#): > > Fine, I was being a bit whimsical with the pencil thing, but to be more [del]pedantic[/del] specific: > > “If I take **the mass contained within** this pencil and \_\_\_\_\_ it by 186,000^2 times, then it will yield [so much] energy.” > > Once again, what fills in that blank? “accelerate?” “motivate?” “rejuvinate?” It helps to know what the equation is actually saying. The equation says that if by some process one could _convert the entire mass of the object into pure energy, how much energy would it yield_? There isn’t really such a process for something like a pencil, the equation mostly applies to small particles like protons and electrons. As an example, if an electron and its antimatter counterpart the positron collide, they evaporate in a big explosion. That explosion contains the energy of their combined masses times _c_[sup]2[/sup]. The important thing is that once this happens, the mass is gone, it has completely converted into the energy of the explosion. It’s not very intuitive why the speed of light would govern how much energy is contained within mass, but it’s a fundamental constant of nature and it pops up in all kinds of unexpected places. ---
**Author:** ![Koxinga](https://avatars.discourse-cdn.com/v4/letter/k/4af34b/32.png) [@Koxinga](https://boards.straightdope.com/u/Koxinga)\ **Post date:** [May 17, 2010, 5:19am UTC](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836/132 "2010-05-17T05:19:29Z")
> [@Yumblie](#): > > That explosion contains the energy of their combined masses times _c_[sup]2[/sup]. Okay I think I nearly get it now . . . except, is there a common unit of measurement for both energy and mass? E.g., “What’s the current mass of that pencil?” “About 5 billion gigawatts.” ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [May 17, 2010, 5:24am UTC](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836/133 "2010-05-17T05:24:13Z")
> [@Askance](#): > > I’ve worked in IT and communications for over 30 years and I still can’t remember the [OSI Model](http://en.wikipedia.org/wiki/OSI_model) of the various layers common to all network protocols. That’s because it _isn’t_ common to all of them. It’s only really useful in reference to the OSI protocol suite, which approximately nobody uses these days. The Internet protocol suite won for any large-to-medium-scale use and things like USB and FireWire won for things we used to use RS232 or other specialized cables for. The Internet protocol suite is most usefully divided into four layers, but it really isn’t designed with layering in mind at all. Those four layers are physical (including DSL, Ethernet, and Wifi), Internet (including IP), transport (including TCP and UDP), and application (including HTTP, SMTP, and so on). Again, layering is just a sometimes-useful mental model, not a law of the networking universe. And, again, there’s nothing especially useful about the OSI model. ---
**Author:** ![Cardinal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cardinal/32/4000_2.png) [@Cardinal](https://boards.straightdope.com/u/Cardinal)\ **Post date:** [May 17, 2010, 6:27am UTC](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836/134 "2010-05-17T06:27:36Z")
> [@Koxinga](#): > > Okay I think I nearly get it now . . . except, is there a common unit of measurement for both energy and mass? E.g., “What’s the current mass of that pencil?” “About 5 billion gigawatts.” There isn’t a common unit of measurement for matter and mass; in fact, what made Einstein more famous than famous was the idea that matter and energy were somehow expressions of the same thing, and could theoretically be converted into each other. I don’t think we’ve ever converted energy into mass, but to be very nerdy, any time energy is used, mass is being converted. Unless it’s on the scale of an A bomb, no one notices the difference. So, to your point: There’s no common unit between them exactly, but they both do contain the idea of kg (mass). One (matter) expresses just and only the idea of how much matter an object contains, and one (Joules/energy) tells how much energy was used to do some amount of work. It’s standardized as being the amount of energy needed to take 1kg of matter from say, 2 meters per second speed to 3 meters per second speed. Nerds: I realize in my previous point I think I actually used the definition of a Watt. Let’s let that go… Or to say it another way, Einstein was saying that there’s no real distinction between expressing a value as mass or energy, since the two are theoretically interchangeable. In practical terms, though, since the only method we have to convert mass to energy on a significant scale is a nuclear reactor or A-bomb, we just use Joules for energy and kg for mass/matter, or pounds, if you’re really American about it and not being super nerdy about the terms. ---
**Author:** ![Little\_Nemo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/little_nemo/32/3120_2.png) [@Little\_Nemo](https://boards.straightdope.com/u/Little_Nemo)\ **Post date:** [May 17, 2010, 7:31am UTC](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836/135 "2010-05-17T07:31:21Z")
> [@](#): > > There isn’t a common unit of measurement for matter and mass; in fact, what made Einstein more famous than famous was the idea that matter and energy were somehow expressions of the same thing, and could theoretically be converted into each other. I don’t think we’ve ever converted energy into mass, but to be very nerdy, any time energy is used, mass is being converted. Unless it’s on the scale of an A bomb, no one notices the difference. I, for one, am still confused. I understand the basic concept that mass and energy can be converted into each other and that a small amount of mass equals a large amount of energy. But E=mc2 implies a very precise equivalence. It says that 1 “unit” of mass is equal to c2 “units” of energy. So what are these units that this is being measured in? It can’t be a universal formula. A mass of one gram and a mass of one ton are obviously not going to produce the same amount of energy. And for that matter, what units are you measuring C in? Miles per hour? Meters per second? Furlongs per fortnight? ---
**Author:** ![adhay](https://avatars.discourse-cdn.com/v4/letter/a/ecd19e/32.png) [@adhay](https://boards.straightdope.com/u/adhay)\ **Post date:** [May 17, 2010, 12:50pm UTC](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836/136 "2010-05-17T12:50:23Z")
> [@llcoolbj77](#): > > Lawyer here: I just don’t get _Marbury v. Madison_. This case is absolutely fundamental. It is the very first case in almost every single Constitutional Law textbook. Something about writs of mandamus… or appointments to the Supreme court. :smack: IANAL but let me try. In M v M, SCOTUS asserted it’s “right” to be the supreme legislative body. Congress acquiesced and here we are today. Perhaps I oversimplify. ---
**Author:** ![Really\_Not\_All\_That\_Bright](https://avatars.discourse-cdn.com/v4/letter/r/e8c25b/32.png) [@Really\_Not\_All\_That\_Bright](https://boards.straightdope.com/u/Really_Not_All_That_Bright)\ **Post date:** [May 17, 2010, 1:31pm UTC](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836/137 "2010-05-17T13:31:42Z")
> [@adhay](#): > > IANAL but let me try. In M v M, SCOTUS asserted it’s “right” to be the supreme legislative body. Congress acquiesced and here we are today. Perhaps I oversimplify. Erm, no. SCOTUS asserted that the Constitution grants it the power and duty of _judicial review_ - to determine whether acts of Congress conflict with the Constitution - and to strike down those acts if so. Otherwise, it might very well have been assumed - as in Britain from about 1688 until quite recently - that Congress itself was to determine whether its acts were constitutional, and to self-regulate. I suppose you could say SCOTUS asserted its right to be the supreme arbiter of the constitutionality of legislation (in Marbury), but it certainly didn’t assert a right to be a legislative body. One might argue that SCOTUS has _since_ asserted itself as a legislative body (I wouldn’t), but it did not do so in Marbury. ---
**Author:** ![bouv](https://avatars.discourse-cdn.com/v4/letter/b/bc8723/32.png) [@bouv](https://boards.straightdope.com/u/bouv)\ **Post date:** [May 17, 2010, 2:08pm UTC](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836/138 "2010-05-17T14:08:26Z")
> [@Little\_Nemo](#): > > But E=mc2 implies a very precise equivalence. It says that 1 “unit” of mass is equal to c2 “units” of energy. It’s not saying that at all. The m and c[sup]2[/sup] are on _the same side_ of the equals sign. They aren’t equal to each other, they (multiplied together) are equal to some amount of energy. If the equation were this: c[sup]2[/sup] = m then you would be right…but that’s not the equation. The energy (the big E on the left of the equation) is what is being measured and comapred to the mass, not the speed of light (the c.) That is just a proprtionality constant. But you are right that units matter…to a point. You can measure both the speed of light and the mass in any units you want…so long as it’s a unit related to mass/speed. You can have mass in kg and c be in ft/hours (which, after it was squared, would be feet[sup]2[/sup]/hour[sup]2[/sup]) All the units of m and c do is affect what units the energy, E, will be in. Since there isn’t a standard unity of energy for kg\*ft[sup]2[/sup]/hour[sup]2[/sup], iut would be pretty darn silly to use those as units, but there is technically nothing stopping you from doing it. However, in SI (it’s short for le Système international d’unités, ie international system of units) the units or Joules for energy, kg for mass, amd meters per second for the speed of light (c) (which, after you square it, becomes m[sup]2[/sup]/s[sup]2[/sup]. So 1 Joule is the same thing as 1 kg\*meter[sup]2[/sup]/second[sup]2[/sup] ---
**Author:** ![Koxinga](https://avatars.discourse-cdn.com/v4/letter/k/4af34b/32.png) [@Koxinga](https://boards.straightdope.com/u/Koxinga)\ **Post date:** [May 17, 2010, 2:21pm UTC](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836/139 "2010-05-17T14:21:25Z")
> [@bouv](#): > > So 1 Joule is the same thing as 1 kg\*meter[sup]2[/sup]/second[sup]2[/sup] How on earth do you “multiply” a kilogram by a meter (fine, a meter squared), and how do you “divide” either one of them by a second squared (which itself doesn’t make much sense). I have a feeling you’re going to come back with “you’re hung up on the units, all that matters is the numbers,” but that puts us right back where we started. ---
**Author:** ![adhay](https://avatars.discourse-cdn.com/v4/letter/a/ecd19e/32.png) [@adhay](https://boards.straightdope.com/u/adhay)\ **Post date:** [May 17, 2010, 2:32pm UTC](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836/140 "2010-05-17T14:32:01Z")
> [@Really\_Not\_All\_That\_Bright](#): > > Erm, no. > > SCOTUS asserted that the Constitution grants it the power and duty of _judicial review_ - to determine whether acts of Congress conflict with the Constitution - and to strike down those acts if so. Otherwise, it might very well have been assumed - as in Britain from about 1688 until quite recently - that Congress itself was to determine whether its acts were constitutional, and to self-regulate. > > I suppose you could say SCOTUS asserted its right to be the supreme arbiter of the constitutionality of legislation (in Marbury), but it certainly didn’t assert a right to be a legislative body. One might argue that SCOTUS has _since_ asserted itself as a legislative body (I wouldn’t), but it did not do so in Marbury. I am aware that that the idea of judicial review had been around for a while. My post was (only partially) in jest. And certainly off-topic. I’m willing to leave it here. [Previous page](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836.md?page=6) [Next page](https://boards.straightdope.com/t/painful-confession-time-things-you-ought-to-know-but-dont/537836.md?page=8)