Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Trinity College experiment succeeds after 69 years

rte.ie

Post reply on HN
Print view View original

91–100 of 119 posts

Re: Trinity College experiment succeeds after 69 years

#91

Post by ColinWright »

samatman wrote: post #87
robomartin wrote: post #75

Earlier quoted context omitted.

> Chemist here. We use centrifuging to separate components of a suspension by weight. Pitch is a suspension. The last bit is puzzling: Are all suspensions fluids? And all fluids are viscous (even non-newtonian)? If so, why do we need an experiment to prove that pitch --a suspension-- is a fluid and is viscous? On the point of using a centrifuge. Is there something particularly special about gravity on earth that does…

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 since some suspensions definitely are fluids, then you must have meant that there are suspensions that are not fluids.

But this is about science, and where possible, I believe we should be precise.

I believe it matters.

Re: Trinity College experiment succeeds after 69 years

#92

Post by vacri »

peterkelly wrote: post #10
dalore wrote: post #6

Earlier quoted context omitted.

How are they different? Both the article and the wikipedia link you gave mention they are similar experiments. It seems they are the same experiment to me.

The theory is that the Australian one will drip upside-down

That's how we get the pitch into the funnel in the first place!

Re: Trinity College experiment succeeds after 69 years

#93

Post by negativity »

lightcatcher wrote: post #65
negativity wrote: post #42

Earlier quoted context omitted.

It gets finnier if you imagine Stephen Hawking saying "I told you so." to Leonard Susskind. D'OOOH... WERNSTROM!!!

You might find this to be "finny": http://en.wikipedia.org/wiki/Thorne%E2%80%93Hawking%E2%80%93...

Finny is a perfectly cromulent word, sir...

Re: Trinity College experiment succeeds after 69 years

#94

Post by robomartin »

samatman wrote: post #89
robomartin wrote: post #75

Earlier quoted context omitted.

> Chemist here. We use centrifuging to separate components of a suspension by weight. Pitch is a suspension. The last bit is puzzling: Are all suspensions fluids? And all fluids are viscous (even non-newtonian)? If so, why do we need an experiment to prove that pitch --a suspension-- is a fluid and is viscous? On the point of using a centrifuge. Is there something particularly special about gravity on earth that does…

To answer your second question, there is some critical number, which we do not know empirically, after which pressure will separate pitch. We could apply some higher acceleration for a shorter time, but that acceleration would have to be highly consistent, and there is no way to shorten the experiment enough to keep that equipment from being unproductive to even contemplate. Sometimes patience really is the best answ…

OK, had a break so I looked around a little to see what I could learn [1], [2], [3] and [4] are my launching points.

So I read that asphalt is actually a colloid and that pitch is not the same as asphalt. The Wikipedia page on pitch [3] says it is a "viscoelastic polymer".

So I have to ask. Can a polymer be a suspension or a colloid on its own or is pitch a polymer colloid in another "host" substance?

[1] http://en.wikipedia.org/wiki/Suspension_(chemistry)

[2] http://en.wikipedia.org/wiki/Asphalt

[3] http://en.wikipedia.org/wiki/Pitch_(resin)

[4] http://en.wikipedia.org/wiki/Colloids

Re: Trinity College experiment succeeds after 69 years

#95

Post by blahedo »

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…

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 you said literally", because there are multiple correct literal interpretations of what he said---he is not using a metaphor or anything. There are many cases where "not" can scope out to an enclosing quantifier (one of the better-known is "All that glitters is not gold", famously by Tolkien), and this is not just because all these speakers are in error.

[0] Also computer scientist, but I'll wear my linguist hat for now.

Re: Trinity College experiment succeeds after 69 years

#96

Post by samatman »

robomartin wrote: post #94
samatman wrote: post #89

Earlier quoted context omitted.

To answer your second question, there is some critical number, which we do not know empirically, after which pressure will separate pitch. We could apply some higher acceleration for a shorter time, but that acceleration would have to be highly consistent, and there is no way to shorten the experiment enough to keep that equipment from being unproductive to even contemplate. Sometimes patience really is the best answ…

OK, had a break so I looked around a little to see what I could learn [1], [2], [3] and [4] are my launching points. So I read that asphalt is actually a colloid and that pitch is not the same as asphalt. The Wikipedia page on pitch [3] says it is a "viscoelastic polymer". So I have to ask. Can a polymer be a suspension or a colloid on its own or is pitch a polymer colloid in another "host" substance? [1] http://en.w…

Pitch is also a colloidal suspension, or colloid. The various polymers that make it up are not of equal weight, and there are little bits of graphite in there too. The chemistry of pitch is by no means simple, destructive distillation can go in many directions.

Re: Trinity College experiment succeeds after 69 years

#98

Post by timdellinger »

samatman wrote: post #68
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…

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.

Re: Trinity College experiment succeeds after 69 years

#99

Post by Wingman4l7 »

peterkelly wrote: post #84
stinkytaco wrote: post #83

Earlier quoted context omitted.

Really, it seems like a dream gig. Just being a student for years and years and continuing to get financial aid to continue your thesis work. I've often said if I could be a student for life I'd be happy. I was just picking the wrong field of study. Viscous fluids, here I come.

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.

Sometimes your advisors, if they have grant funding, will cover you for an additional extension. (Source: I know someone who is a PhD student at ANU).

Re: Trinity College experiment succeeds after 69 years

#100

Post by ok_craig »

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…

The mathematician had a better point.
Post reply on HN