## Search found 68 matches

Mon Dec 09, 2013 6:47 am UTC
Forum: Science
Topic: Can someone explain more about the Higgs Boson and mass?
Replies: 24
Views: 5765

### Re: Can someone explain more about the Higgs Boson and mass?

The rest of the mass that makes the proton heavy is a lot of energy. And, in quantum chromodynamics, this energy can be considered as pairs of quarks/antiquarks formed with decays of gluons, so the Higgs bosons consider this as a mass. This is not entirely correct. Without Higgs mechanism, bare qua...
Fri Jan 18, 2013 3:22 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 1162: "Log Scale"
Replies: 135
Views: 30748

### Re: 1162: "Log Scale"

Just take the number you wish to record and convert it to a fraction with one as the numerator. Take a metal bar of a known length, say one meter. Cut the bar to the exact length of the fraction. When you need to know the number, measure the bar and reverse the process. :twisted: Bob (who has a ver...
Fri Jan 18, 2013 2:44 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 1162: "Log Scale"
Replies: 135
Views: 30748

### Re: 1162: "Log Scale"

What about this Thorium stuff? I know it's been tried for ages with little proof of success, but it keeps showing up on my FB stream as THE thing. Thorium fuel cycle takes Th-232 to U-233 (neutron capture + beta decay twice.) U-233 gives you 200MeV of energy. That's 0.925% of mass. U-235 reaction, ...
Fri Jan 18, 2013 11:18 am UTC
Forum: Individual XKCD Comic Threads
Topic: 1162: "Log Scale"
Replies: 135
Views: 30748

### Re: 1162: "Log Scale"

I tried writing the number of iterations on some paper, but the stack of pages with that number won't fit in the room. Please advise. Just use the Knuth Paper-Stack Notation again. If the number of iterations of that stack still doesn't fit in its note, repeat. The room, well, more of a warehouse, ...
Fri Jan 18, 2013 9:11 am UTC
Forum: Individual XKCD Comic Threads
Topic: 1162: "Log Scale"
Replies: 135
Views: 30748

### Re: 1162: "Log Scale"

I tried writing the number of iterations on some paper, but the stack of pages with that number won't fit in the room. Please advise. Can we use the others for nuclear fission? I ask because I know very little about this subject. Fission? No. But hydrocarbons consist of elements that can be used for...
Wed Apr 04, 2012 10:46 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 1038: "Fountain"
Replies: 78
Views: 21939

### Re: 1038: "Fountain"

3. If it wouldn’t be ripped out, it would break his arm. (1500N! That’s more than the biggest monster of a supercar on Top Gear!) 4. If he would have monster arms, a monster grip and a monster umbrella, he’d still break his neck after coming down. You are way off. 1500N is about twice the weight of...
Wed Apr 04, 2012 5:45 am UTC
Forum: Individual XKCD Comic Threads
Topic: 1038: "Fountain"
Replies: 78
Views: 21939

### Re: 1038: "Fountain"

Approximating the man as 1.7m, the spout should be around 17.9cm in diameter. Which would double thrust estimate. But compared to his head, the aperture is much smaller. So I kind of just eye-balled it at 10cm. Either way, the thrust is sufficient. You just need something sturdy enough to "gra...
Wed Apr 04, 2012 4:15 am UTC
Forum: Individual XKCD Comic Threads
Topic: 1038: "Fountain"
Replies: 78
Views: 21939

### Re: 1038: "Fountain"

Fountain about 10m tall at v²=2gh, or about 17m/s out of what appears to be an aperture of roughly 10cm in diameter, or about 75cm². That's 167.5L/s flow, which if brought to a stop would generate 1500N of force. More than enough to lift an adult male, but not very high, as thrust will drop off quic...
Mon Nov 14, 2011 8:26 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0977: "Map Projections"
Replies: 353
Views: 138565

### Re: 0977: "Map Projections"

http://en.wikipedia.org/wiki/Gnomonic_projection Is what you are looking for, I think. Indeed it is. I was trying to solve the differential equation for geodesics just now to get the projection, and now I can see why I was having trouble with it. I should have thought to switch to polar coordinates...
Mon Nov 14, 2011 7:41 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0977: "Map Projections"
Replies: 353
Views: 138565

### Re: 0977: "Map Projections"

I feel that my maps should be practical. If I'm using it for navigation, it damn better be a Mercator. You ever tried to navigate by other projections? Don't even bother. For political maps, you can't go wrong with Hobo-Dyer. If I need a map I'm going to map onto a rendered sphere, why in the world ...
Wed Nov 09, 2011 8:33 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0975: "Occulting Telescope*
Replies: 2
Views: 1914

### Re: 0975: "Occulting Telescope*

Hmm, I guess I'll post in this one because it has an actual link. I always thought a Dyson sphere would be almost impossible to construct in real life, as we have neither sufficiently strong materials, nor enough of them even if they existed for it to work. I realize if it's at Kardashev Type II, t...
Thu Oct 20, 2011 6:43 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0966: "Jet Fuel"
Replies: 168
Views: 41104

### Re: 0966: "Jet Fuel"

OK - I'll grant melting part of a beam with jet fuel. That's fine. We're talking 1) Having enough fuel. Close your eyes and remember the planes hitting and a large gasoline (jet fuel) explosion occuring. Did some fuel escape the fire ball? Would the fireball have been smaller if it had? I don't kno...
Wed Oct 19, 2011 6:55 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0966: "Jet Fuel"
Replies: 168
Views: 41104

### Re: 0966: "Jet Fuel"

Jet-A1 burns at 2000 degrees Celsius. Carbon steel melts to a liquid at 1400 Celsius (yes that low!). There are stronger steel alloys but they dont build buildings out of them because nobody can afford it, also the towers were the height (sic) of 60s/70s technology when they were built. Jet-A1, as ...
Tue Sep 27, 2011 4:12 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0955: "Neutrinos"
Replies: 159
Views: 44512

### Re: 0955: "Neutrinos"

The granite block is located at the end of the decay tunnel. If it was on detector side, yeah, that would be something to look into. But it seems like they are measuring distance directly from decay detector (scintillator + photo multiplier?) to the neutrino detector. That would exclude possibility ...
Mon Sep 26, 2011 1:06 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0955: "Neutrinos"
Replies: 159
Views: 44512

### Re: 0955: "Neutrinos"

The thing about tunneling is that it should be random for each particle, so therefore we should see a Gaussian distribution in the "excess speed" of the neutrinos--e.g. some would be 80 ns ahead and some would be 40 ns ahead. In other words, there should be some "blurring" of th...
Mon Sep 26, 2011 5:11 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0955: "Neutrinos"
Replies: 159
Views: 44512

### Re: 0955: "Neutrinos"

A tunneling particle can violate locality. Just take a plane wave solution under barrier, substitute in packet of your choice, and provided your choices don't cause too much packet distortion, you should see that time of transit can be less than for particle to propagate at speed of light. If you ca...
Fri May 20, 2011 3:01 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0899: "Number Line"
Replies: 355
Views: 81219

### Re: 0899: "Number Line"

In fact, whether we are talking about strictly rational numbers or real numbers, all of these infinities fall under the same \aleph class. Not sure what you mean by aleph class. The aleph number for rationals and reals is different, since former is countable. Rationals are still dense, however, so ...
Fri May 20, 2011 12:51 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0895: "Teaching Physics"
Replies: 112
Views: 32422

### Re: 0895: "Teaching Physics"

According to GR, if you are in this ship and accelerate at A (as measured in m/s^2), your accelerometer will measure A (in Newtons of force divided by a known mass in the accelerometer). And if the universe somehow accelerates at -A (as measured in m/s^2), your accelerometer will measure something ...
Thu May 19, 2011 10:31 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0899: "Number Line"
Replies: 355
Views: 81219

### Re: 0899: "Number Line"

Now I doubt your sanity. 0+0=0 0+0+0=0 0+0+0+0=0 extrapolate to infinity. That's not how multiplication is defined. That's just what they told you in elementary school because you wouldn't understand ring algebra. There are two relevant axioms for multiplication: 1) a*1=1*a=a 2) a*(b+c)=a*b+a*c Usi...
Thu May 19, 2011 10:12 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0895: "Teaching Physics"
Replies: 112
Views: 32422

### Re: 0895: "Teaching Physics"

How does it contradict Mach's principle that your inertia would be relative to the mass of other objects in the universe, and thus the acceleration you measure will be doubled by a doubling of the only other mass in the universe, as GR predicts via frame dragging? You seem to have trouble with rela...
Thu May 19, 2011 10:13 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0899: "Number Line"
Replies: 355
Views: 81219

### Re: 0899: "Number Line"

If you can show that the precise decimal expansion of 1/3 is an unending series of threes after a decimal point (e.g. show that dividing one into three by long division requires you to keep writing more threes forever as you try to get rid of your remainder), doesn't it follow directly that an unen...
Thu May 19, 2011 10:04 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0895: "Teaching Physics"
Replies: 112
Views: 32422

### Re: 0895: "Teaching Physics"

No co-acceleration. Forget that. You are making things more complicated than they need to be. Mach's Principle first. A massive object accelerates relative to you. Since it is the only object in the universe of significant mass, its acceleration relative to you is what you are going to measure by an...
Wed May 18, 2011 11:58 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0899: "Number Line"
Replies: 355
Views: 81219

### Re: 899: "Number Line"

Really, though, that wasn't my primary argument, just a rewording of the results. Just do the long division and the answer is obvious. No matter how many decimal places you carry it out to, the next digit is always 3. You can say this for sure because you are explicitly dividing two numbers. 0.9......
Wed May 18, 2011 11:53 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0895: "Teaching Physics"
Replies: 112
Views: 32422

### Re: 0895: "Teaching Physics"

Two problems with the above. First of all, frame dragging causes acceleration of a reference frame. Agreed, you might call that semantics, but it is technically important for the next point. Suppose, the universe consists of you and a billion ton object. That object accelerates, and you feel the tug...
Wed May 18, 2011 9:17 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0899: "Number Line"
Replies: 355
Views: 81219

### Re: 899: "Number Line"

Wait... can someone who's finished second-grade math argue with that equivalence? Doing simple long division, one can see that stopping the threes at any point would be less than 1/3, and capping it with a digit larger than three would be greater than 1/3. Therefore 0.3... must be 1/3 by the "...
Wed May 18, 2011 9:13 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0895: "Teaching Physics"
Replies: 112
Views: 32422

### Re: 0895: "Teaching Physics"

Source for that please? Acceleration in GR is a covariant derivative, which is independent of frame of reference. Acceleration is absolute, and so you can measure acceleration of your own frame of reference absolutely. That's in any GR textbook. I hope I don't need to quote a specific one. Mach's P...
Wed May 18, 2011 8:57 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0899: "Number Line"
Replies: 355
Views: 81219

### Re: 0899: "Number Line"

I claim that sequence (0.9, 0.99, 0.999, ..., 1-10^(-n), ...) has a limit and it is 1. I think an additional problem is that people don't realize the limit of that sequence is *also* what's meant by the single number, 0.999... That's basically where I was coming from with that sequence, yeah. Proba...
Wed May 18, 2011 7:06 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0895: "Teaching Physics"
Replies: 112
Views: 32422

### Re: 0895: "Teaching Physics"

And the fact that General Relativity actually disagrees with Mach's Principle does not bother you one bit, right? According to Mach's Principle, acceleration is relative. According to GR, acceleration is absolute.
Wed May 18, 2011 6:49 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0899: "Number Line"
Replies: 355
Views: 81219

### Re: 0899: "Number Line"

I accept most of what you are saying but I cannot accept the idea of converging to zero. It can get close to zero but never actually reach it. It seems mathematicians have come up with a method of dealing with what is essentially an abstract concept so they can work with it. This does not mean that...
Wed May 18, 2011 12:26 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0895: "Teaching Physics"
Replies: 112
Views: 32422

### Re: 0895: "Teaching Physics"

I don't know enough string theory to say if this is in any kind of disagreement. But seeing how there is still no serious experimental support for string theory, it really wouldn't be a deal-breaker. If it can be made to work as a classic field theory, I'd be happy with it.
Wed May 18, 2011 11:43 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0895: "Teaching Physics"
Replies: 112
Views: 32422

### Re: 0895: "Teaching Physics"

Maybe the universe is on the surface of a rotating hypersphere, and massive objects pull the fabric outward because of the the centripetal force... That... is... brilliant. Not the rotating hypersphere. That part's rubbish. But the idea that the distortions in space-time are due to energy trying to...
Wed May 18, 2011 11:24 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0899: "Number Line"
Replies: 355
Views: 81219

### Re: 0899: "Number Line"

Similarly, anything divided by infinity is not 0, it's just a very small amount. 1/infinity = 0 therefore 1 = 0 x infinity 1 = 0 Do I win a prize? You're on the right track, but your conclusion is wrong. 1/infinity cannot be zero. Your proof of that is flawless. So that leaves two possibilities. It...
Wed May 18, 2011 5:20 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0899: "Number Line"
Replies: 355
Views: 81219

### Re: 899: "Number Line"

Is this actually true? You are replying to a person who wants to say that the difference is an infinitesimal. Does your limit exist if you allow those. The reason I am asking: Assume that 1/infinity is an infinitesimal. Ie. it's a number that is smaller than all positive reals. Then it seems to me ...
Tue May 17, 2011 9:22 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0899: "Number Line"
Replies: 355
Views: 81219

### Re: 899: "Number Line"

∞ is as accurate as ≈ and that is precisely my point. It's truly amazing to me that you can see that without seeing that. Ask yourself why one divided by the "concept" of infinity (happy now?) "is" equal to zero. Oh joyous semantics; as improper as we interpret, as valid as we e...
Mon May 16, 2011 11:39 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0899: "Number Line"
Replies: 355
Views: 81219

### Re: 899: "Number Line"

Infinity is a concept, correct? It's not actually a number. So 0.999bar should be the concept of 1 - 1/infinity. If you're subtracting anything from one, that is not zero, you get a result that is not one. That's because this isn't what 0.9(9) means. The bar/parenthesis mean "take limit of the...
Mon May 16, 2011 10:51 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0899: "Number Line"
Replies: 355
Views: 81219

### Re: 899: "Number Line"

You're right. The difference must be infinitely small, thus zero. It seems like any two "adjacent" real numbers must be the same number in different notation. Real numbers are funny things. You can think about it that way. The problem is that there is no such thing as "adjacent"...
Mon May 16, 2011 9:48 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0899: "Number Line"
Replies: 355
Views: 81219

### Re: 899: "Number Line"

I'm still thinking that if these two numbers are equal they must all be equal, otherwise at what point do they become unequal? If someone wants to be consistent and say they are equal, I respect that. What's inequality between numbers exactly anyway? Perhaps you can build a theory that way. (Or may...
Mon May 16, 2011 8:57 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0899: "Number Line"
Replies: 355
Views: 81219

### Re: 899: "Number Line"

meerta wrote:If 0.999 to infinity is equal to one, then all numbers must be equal, right? Otherwise where is the distinction?

Any number can be written in a number of alternate notations. It doesn't mean that you can't differentiate between numbers. You just need to know what a notation means.
Mon May 16, 2011 8:22 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0899: "Number Line"
Replies: 355
Views: 81219

### Re: 899: "Number Line"

If Gird is integer, then so is Gird-3. 3 < Gird < 4 => 0 < Gird-3 < 1. So the integer line is now ... -2, Gird-5, -1, Gird-4, 0, Gird-3, 1, Gird-2, 2, Gird-1, 3, Gird, 4, Gird+1, 5, ... Nothing technically wrong with that, but it kind of hangs on what Gird+Gird is.
Mon May 16, 2011 7:47 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0899: "Number Line"
Replies: 355
Views: 81219

### Re: 899: "Number Line"

Divide by 3 argument simply appeals to something a person finds obvious. If you try to actually prove that .3(3) is equal to 1/3, you'll find that you are using a proof that you might as well apply directly to .9(9). Of course, this is where you have to rely on the definition of the infinitely repea...

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