Trinity College experiment succeeds after 69 years • Hacker News Board

Re: Trinity College experiment succeeds after 69 years

#101

Post by samatman » Fri, Jul 19, 2013, 12:31 AM UTC

ColinWright wrote: post #91

samatman wrote: post #87

Earlier quoted context omitted.

No, all suspensions are not fluids. Amorphous rocks, for an example, often contain microcrystals in suspension. They will not flow under any circumstances. Glass can have all sorts of powders suspended in it, and is not a fluid. Pitch can be proven to be a suspension via distillation. To prove it's a fluid, it must be observed to flow, to form a droplet, and to detach that droplet in the manner of a fluid.

Mathematician here. Yes, this is about to be a nitpick, and I apologize in advance. However: > No, all suspensions are not fluids. I think what you mean is "No, not all suspensions are fluids." Interpreting what you said literally would imply that anything that is a suspension is definitely not a fluid. And I know one can interpret what you said according to common sense to deduce that you didn't mean that, and that…

The question was "are all suspensions fluids"?

My answer was "No, all suspensions are not fluids". The structure depended from the phrasing of the question.

Re: Trinity College experiment succeeds after 69 years

#102

Post by rtkwe » Fri, Jul 19, 2013, 12:46 AM UTC

throwit1979 wrote: post #22

Um, not to take away from the achievement of the result, but couldn't this result have been obtained in much less time with higher force than 1G in, say, a centrifuge?

That would be another variable to account for and isn't the a standard test for viscosity. Also with pitch being this viscous having a centrifuge capable of spinning fast enough and long enough would be troublesome.

Re: Trinity College experiment succeeds after 69 years

#103

Post by samatman » Fri, Jul 19, 2013, 1:10 AM UTC

timdellinger wrote: post #98

samatman wrote: post #68

Earlier quoted context omitted.

Chemist here. We use centrifuging to separate components of a suspension by weight. Pitch is a suspension. The heavy stuff would drop to the outside, the viscosity would be affected, no experiment.

Just letting a suspension sit on the laboratory bench does the same thing: gravity separates the components by density (not weight). That's why you stir paint before you use it: it has partially separated, and has done so without the without the use of a centrifuge.

It is in fact density, although in my defense I meant molecular weight. But was still wrong ;-)

However, there are many suspensions which will never settle under standard gravity, but which will rapidly settle in a centrifuge. We call these colloids.

Re: Trinity College experiment succeeds after 69 years

#104

Post by LeeLorean » Fri, Jul 19, 2013, 1:25 AM UTC

dokem wrote: post #78

why did the pitch have to drip? Isn't the fact that a drip was forming proof that the pitch was flowing?

Seems like it to me. Maybe they thought the whole drop quantam tunneled to the bottom

I guess you could have asked that if you find a tree that's fallen in a forrest, did it actually fall over if no one saw it?

Re: Trinity College experiment succeeds after 69 years

#105

Post by scythe » Fri, Jul 19, 2013, 1:59 AM UTC

robomartin wrote: post #36

The first thought that popped into my punny little brain was: Why didn't they use a centrifuge to accelerate results? The one variable that could be controlled is the gravitational force on the substance. If we were on the moon the experiment, as designed, would take far longer to produce a drop. By using a centrifuge they could have easily simulated significantly greater gravitational forces and arrived at a result…

Centrifuges don't provide a uniform field. The centrifugal pseudopotential is V(r) ~ Ω^2 / r^2; in effect this means that the pitch near the outside of the centrifuge experiences more "gravity". If you want to study pitch in a uniform gravitational field, you'd either need an absurdly large centrifuge -- the size of the Pentagon -- or a solar sail to Jupiter.

edit: also, the Earth's gravity might become a problem.

Re: Trinity College experiment succeeds after 69 years

#106

Post by Dylan16807 » Fri, Jul 19, 2013, 2:01 AM UTC

user24 wrote: post #41

I sort of take issue with "experiment succeeds". You don't (shouldn't) set up an experiment to prove or disprove something, merely to discover. I'm sure the issue, if indeed there is one, is with the reporting not the scientists though.

It succeeded in making a measurement. That was the goal of the experiment, not proving or disproving anything in particular.

Re: Trinity College experiment succeeds after 69 years

#107

Post by Zuider » Fri, Jul 19, 2013, 3:01 AM UTC

blahedo wrote: post #95

ColinWright wrote: post #91

Earlier quoted context omitted.

Mathematician here. Yes, this is about to be a nitpick, and I apologize in advance. However: > No, all suspensions are not fluids. I think what you mean is "No, not all suspensions are fluids." Interpreting what you said literally would imply that anything that is a suspension is definitely not a fluid. And I know one can interpret what you said according to common sense to deduce that you didn't mean that, and that…

Linguist here.[0] Yes, this is a nitpick, but no apologies, because this is Hacker News. :) Unfortunately, languages don't always work the way that logicians would like them to do. Yes, we can read that sentence as the English-language summary of a logical formula (something like ∀x [Sx -> ¬Fx]), but English (and many other languages) treat the scope of the "not" as ambiguous. It's not a matter of "interpreting what…

For me, It violates the principle of least surprise to encounter a sentence like "all birds do not fly". I have to do a double take and reinterpret the sentence to realise its intended meaning.

Re: Trinity College experiment succeeds after 69 years

#108

Post by andrewflnr » Fri, Jul 19, 2013, 3:25 AM UTC

blahedo wrote: post #95

ColinWright wrote: post #91

Earlier quoted context omitted.

Mathematician here. Yes, this is about to be a nitpick, and I apologize in advance. However: > No, all suspensions are not fluids. I think what you mean is "No, not all suspensions are fluids." Interpreting what you said literally would imply that anything that is a suspension is definitely not a fluid. And I know one can interpret what you said according to common sense to deduce that you didn't mean that, and that…

Linguist here.[0] Yes, this is a nitpick, but no apologies, because this is Hacker News. :) Unfortunately, languages don't always work the way that logicians would like them to do. Yes, we can read that sentence as the English-language summary of a logical formula (something like ∀x [Sx -> ¬Fx]), but English (and many other languages) treat the scope of the "not" as ambiguous. It's not a matter of "interpreting what…

IMO, if "all these speakers" collectively make the language ambiguous, then clearly someone is in error, because unambiguity[0] is essential to the primary purpose of language: communication. This has nothing to do with whether one is a logician or mathematician.

A sentence like "all X are not Y" naturally associates like "all X are (not Y)". Usually modifiers attach to the closest thing they can, as a matter of well-established convention. So if someone decides they want that to mean "not (all X are Y)" and expects me to understand it, I'm going to go ahead and say they're the one in error. Sorry, Tolkien.

[0] Is that a word? Chromium spell-check doesn't like it. I have lightened up on neologisms, as long as it's clear what they mean.

Re: Trinity College experiment succeeds after 69 years

#109

Post by DrewAllyn » Fri, Jul 19, 2013, 4:10 AM UTC

andrewflnr wrote: post #108

blahedo wrote: post #95

Earlier quoted context omitted.

Linguist here.[0] Yes, this is a nitpick, but no apologies, because this is Hacker News. :) Unfortunately, languages don't always work the way that logicians would like them to do. Yes, we can read that sentence as the English-language summary of a logical formula (something like ∀x [Sx -> ¬Fx]), but English (and many other languages) treat the scope of the "not" as ambiguous. It's not a matter of "interpreting what…

IMO, if "all these speakers" collectively make the language ambiguous, then clearly someone is in error, because unambiguity[0] is essential to the primary purpose of language: communication. This has nothing to do with whether one is a logician or mathematician. A sentence like "all X are not Y" naturally associates like "all X are (not Y)". Usually modifiers attach to the closest thing they can, as a matter of well…

Despite the primary purpose of languages being communication, they occasionally fail at it. Does this surprise you? Have you never heard someone say something and completely misinterpreted them?

Re: Trinity College experiment succeeds after 69 years

#110

Post by vacri » Fri, Jul 19, 2013, 6:39 AM UTC

aggronn wrote: post #86

peterkelly wrote: post #84

Earlier quoted context omitted.

If only it were true. In Australia, they give you 3 years (plus an additional 1/2 year extension, which isn't always granted). After that, you're on your own, and many people get a full time job to support themselves. I've seen quite a few people abandon their PhD because of the need to pay the bills once their funding runs out. It's quite sad.

Does everyone get funding? Including liberal arts?

No, you have to apply for a position.

'liberal arts' doesn't have a meaning in Australia, but I'm not aware of PhD applications being treated differently in different fields (or rather, the rules differing)