What-if 0006: "Glass Half Empty"

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Eutychus
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What-if 0006: "Glass Half Empty"

Postby Eutychus » Tue Aug 07, 2012 1:14 pm UTC

http://what-if.xkcd.com/6/

I know I'm a glass half-empty type of person. :(
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Re: What-if 0006: Glass Half Empty

Postby peewee_RotA » Tue Aug 07, 2012 1:18 pm UTC

This one was pretty cool imo.

I think the glass lifting itself is debatable, however. The force of gravity on the glass and it's friction against the table would need to be overcome. Something that the water itself wouldn't have to contend with. In fact the force of gravity will assist the water in it's descent.

This brings up an interesting question. If the glass remained on the table (whether or not the table lifted off the ground for some odd reason) would the glass still break?
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Re: What-if 0006: Glass Half Empty

Postby RuneWarden » Tue Aug 07, 2012 2:00 pm UTC

What would this experiment result in if conducted in metal cups, or maybe even airtight cups (read- Steins.)? the shockwave would obviously not occur in the second case...

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Re: What-if 0006: Glass Half Empty

Postby davidhbrown » Tue Aug 07, 2012 2:11 pm UTC

Yeah, I'm not getting the lifting up from suction either. But I'll just have to trust Randall 'cause I haven't been able to cause a complete vacuum to spontaneously appear yet. I'll keep trying ;-)

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Re: What-if 0006: Glass Half Empty

Postby rigelan » Tue Aug 07, 2012 2:20 pm UTC

It wouldn't have to overcome friction. Friction of the glass on the table is a horizontal force.

Perhaps he's referring to Newton's third Law?

As the water drops, the glass lifts?

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Re: What-if 0006: Glass Half Empty

Postby rmsgrey » Tue Aug 07, 2012 2:29 pm UTC

peewee_RotA wrote:This one was pretty cool imo.

I think the glass lifting itself is debatable, however. The force of gravity on the glass and it's friction against the table would need to be overcome. Something that the water itself wouldn't have to contend with. In fact the force of gravity will assist the water in it's descent.

This brings up an interesting question. If the glass remained on the table (whether or not the table lifted off the ground for some odd reason) would the glass still break?


The friction against the table isn't an issue - it'd resist the glass skidding sideways if there were a lateral force, but when it comes to lifting the glass away from the table, while there are some intermolecular forces where the glass and table are in contact, they're negligible compared to everything else involved.

A more interesting question is what happens if condensation has built up and there's a ring of water around the base of the glass? It's a fairly common experience that a beermat gets "stuck" to the bottom of a glass by this means (the water forms an airtight seal, so the partial vacuum that forms when gravity tries pulling the mat away lets air pressure press the mat against the base of the glass).

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Re: What-if 0006: Glass Half Empty

Postby rigelan » Tue Aug 07, 2012 2:34 pm UTC

So, if the glass were stuck to the bottom of the table, like with a ring of water, perhaps the glass wouldn't break. The table would just get in the way of any vibration the glass might have.

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Re: What-if 0006: Glass Half Empty

Postby rmsgrey » Tue Aug 07, 2012 2:34 pm UTC

rigelan wrote:It wouldn't have to overcome friction. Friction of the glass on the table is a horizontal force.

Perhaps he's referring to Newton's third Law?

As the water drops, the glass lifts?


Neither the water nor the glass exerts an attractive force on the other, so Newton's third law has nothing to do with it.

The air-pressure lifting the glass is the same phenomenon that keeps a suction cup stuck to the ceiling (until/unless enough air leaks in...), or which can hold an evacuated bronze sphere together against the best efforts of two teams of plough-horses - until the seal is broken, at which point the sphere falls apart on its own...

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Re: What-if 0006: Glass Half Empty

Postby AvatarIII » Tue Aug 07, 2012 2:54 pm UTC

davidhbrown wrote:Yeah, I'm not getting the lifting up from suction either. But I'll just have to trust Randall 'cause I haven't been able to cause a complete vacuum to spontaneously appear yet. I'll keep trying ;-)


I buy that the glass will rise, what I don't buy is that the upper part of the glass will have enough energy to get to the ceiling.

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Re: What-if 0006: Glass Half Empty

Postby rigelan » Tue Aug 07, 2012 2:57 pm UTC

Water does indeed have an attractive force on glass, it forms a meniscus.

But I'm unsure of its strength compared to the weights and forces involved in this discussion.

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Re: What-if 0006: Glass Half Empty

Postby Showsni » Tue Aug 07, 2012 3:34 pm UTC

You know, I've thought this for a long time, but surely it should be the pessimists who view the glass as half full, and the optimists as half empty.

If you view a glass as half full, that means that you think of the natural state of glasses as being empty. "Most glasses are empty, but this one happens to be half full." That's a pessimistic viewpoint!

If you view a glass as half empty, though, you regard the natural state of glasses as being full. "Most glasses are full, but this one happens to be half empty." Surely viewing most glasses in the world as full is the optimistic viewpoint!

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Re: What-if 0006: Glass Half Empty

Postby Qaanol » Tue Aug 07, 2012 3:40 pm UTC

peewee_RotA wrote:I think the glass lifting itself is debatable, however.


davidhbrown wrote:Yeah, I'm not getting the lifting up from suction either. But I'll just have to trust Randall 'cause I haven't been able to cause a complete vacuum to spontaneously appear yet. I'll keep trying ;-)


AvatarIII wrote:I buy that the glass will rise, what I don't buy is that the upper part of the glass will have enough energy to get to the ceiling.


Atmospheric pressure at sea level is over 14 pounds per square inch. That means if your body has a cross-sectional area of 1 square foot, the air is pressing down on you with about 1 ton of force. Luckily it is also pressing up on you with that same 1 ton of force, and in all directions on all exposed parts of your body, with that 14 pounds per square inch. Air pressure is strong.

Say the vacuum region in the water glass is cylindrical with a diameter of about 5 cm (2 inches). Then the upward “suction” force on the glass is about 200 Newtons. The glass probably weighs around 100 grams, so it accelerates upward at 2000 m/s2, or about 200 times more quickly than gravity pulls it downward.

Of course, the glass only has about 2 cm to rise before it runs out of vacuum. The impact from the water will go almost entirely into fracturing the glass, and will barely slow down the cylindrical walls of the glass at all, which end up going about 9 m/s (about 20 mph). That means the glass walls would rise about 4m (13 feet), but they hit the ceiling after about 1.5m while still traveling 7.2 m/s (about 16 mph).

I suspect Randall used slightly different measurements than I did, but the results are comparable. The glass ring will hit the ceiling with plenty of speed to shatter.
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Re: What-if 0006: Glass Half Empty

Postby Zinho » Tue Aug 07, 2012 3:44 pm UTC

AvatarIII wrote:
davidhbrown wrote:Yeah, I'm not getting the lifting up from suction either. But I'll just have to trust Randall 'cause I haven't been able to cause a complete vacuum to spontaneously appear yet. I'll keep trying ;-)


I buy that the glass will rise, what I don't buy is that the upper part of the glass will have enough energy to get to the ceiling.


Well, the math's easy enough.

Assume air pressure only acts on the bottom, and that the glass is circular. Also assume a 6-ft separation between tabletop and ceiling (low table, standard ceiling). kinetic energy (KE) of the glass must equal the potential energy (PE) it loses on the way up, so (m*V^2)/2=mgh. The masses cancel, and you get a minimum speed of about 20ft/s to reach the ceiling.

Acceleration can be derived from V(t)=V0+a*T to give a=V/T for a body that starts at rest. That gives about 2000ft/s^2 of acceleration or about 62 gravities of force applied to the cup over .01s to reach the necessary 20ft/s.

Pressure is force divided by area (P=F/A). Estimate air pressure at 15psi, and the cup's weight at 1 pound. Solve for area (A=F/P) and the area you'd need to achieve 62 gravities is 4.13in^2, or about 2.3in diameter.

The mug on my desk has a diameter of 3 in, my water bottle has a diameter of 2.5in. Both would hit the ceiling just fine.

I'll let someone else argue about whether they'd break when they hit; I'm giving Randall the benefit of the doubt that an already-cracked piece of glassware would break more on impact.

*edit* Ninja'ed again! Well, mine's in feet and inches, so may be more persuasive to U.S. readers =P
Also, regarding the meniscus; I'm willing to neglect that. The force only pulls a very small volume of water up a very short distance, so compared to the forces we're talking about it's miniscule. I'd love to argue that a counter-meniscus would form on the vacuum-water-glass interface, but there probably won't be time for that. If you want to make the math more complicated, try for viscous drag against the sides of the glass; it would create a much larger net force on the cup.

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Re: What-if 0006: Glass Half Empty

Postby bsforzo » Tue Aug 07, 2012 3:56 pm UTC

To answer the question of, "will the glass lift off the table?" we need to address where the forces are coming from in the first place. The vacuum in the left glass is not "Pulling" the glass and the water together...this would require some electromagnetic or inter-molecular force...granted, there is gravity between the two, and some molecular forces that cause capillary action (the meniscus). These are fairly negligible. Randall has drawn some capillary effect it seems in the 8ms case though. The main force acting on the water and the glass are that of atmospheric pressure and to less of an effect, earth's gravity. Doing some rough calculations, it looks like the mass of the water would be about 0.25kg, and if the top of the glass is about 8cm (pint glass approx), the pressure of 1atm would exert a force of 509N (equivalent to 114lbs!) on the surface of the water. This would accelerate the water at 2027 m/s^2 (thats 206 g's!). Likewise, if there are any air particles beneath the glass, they would also exert the same force. Once the glass lifts off the table even slightly, more air particles would rush in and apply the force to the bottom of the glass.

If there are no air particles between the glass and the table and there is some sort of adhesion between the two, then the atmospheric pressure on the bottom of the table would compensate, lifting the table slightly.

So the scenario is fairly accurate, including the time scales at which you would notice the movement of things.

The one thing not accounted for are expansion waves. The shockwave caused by the air slamming against the water will reflect off the water and back through the air, and vibrate through the glass on the right picture. In both the right and left cases though, the air rushing in at incredible rates has to come from somewhere, and this causes a rarefaction, or a wave of less dense air. This also travels away from the glasses, just like the shockwaves. And like the shockwaves, is also audible like a crack of thunder.

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Re: What-if 0006: Glass Half Empty

Postby Max™ » Tue Aug 07, 2012 4:29 pm UTC

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Re: What-if 0006: Glass Half Empty

Postby rhomboidal » Tue Aug 07, 2012 4:32 pm UTC

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Re: What-if 0006: Glass Half Empty

Postby yellow103 » Tue Aug 07, 2012 5:15 pm UTC

Atmospheric pressure at sea level is over 14 pounds per square inch. That means if your body has a cross-sectional area of 1 square foot, the air is pressing down on you with about 1 ton of force. Luckily it is also pressing up on you with that same 1 ton of force, and in all directions on all exposed parts of your body, with that 14 pounds per square inch. Air pressure is strong.

Say the vacuum region in the water glass is cylindrical with a diameter of about 5 cm (2 inches). Then the upward “suction” force on the glass is about 200 Newtons. The glass probably weighs around 100 grams, so it accelerates upward at 2000 m/s2, or about 200 times more quickly than gravity pulls it downward.

Of course, the glass only has about 2 cm to rise before it runs out of vacuum. The impact from the water will go almost entirely into fracturing the glass, and will barely slow down the cylindrical walls of the glass at all, which end up going about 9 m/s (about 20 mph). That means the glass walls would rise about 4m (13 feet), but they hit the ceiling after about 1.5m while still traveling 7.2 m/s (about 16 mph).

I suspect Randall used slightly different measurements than I did, but the results are comparable. The glass ring will hit the ceiling with plenty of speed to shatter.

So the glass falls up very fast?

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Re: What-if 0006: Glass Half Empty

Postby Yoduh » Tue Aug 07, 2012 6:15 pm UTC

Showsni wrote:You know, I've thought this for a long time, but surely it should be the pessimists who view the glass as half full, and the optimists as half empty.

If you view a glass as half full, that means that you think of the natural state of glasses as being empty. "Most glasses are empty, but this one happens to be half full." That's a pessimistic viewpoint!

If you view a glass as half empty, though, you regard the natural state of glasses as being full. "Most glasses are full, but this one happens to be half empty." Surely viewing most glasses in the world as full is the optimistic viewpoint!

It's not just me, right?


you're only taking into account the past and present state of a glass, but pessimism/optimism is more about the future state of the glass. pessimists expect the worst, they see the glass going towards empty, to nothingness, a meaningless state of existence. If a pessimist saw an empty glass he would think the future state of the glass would be for it to stay empty, not because empty is its natural state, but because achieving any degree of fullness is unlikely.

optimists will see the glass half full because they believe the glass will eventually be filled, to be whole, to reach a state greater than the one it's currently in. It WAS empty which was an optimist would say is an awful state to be in, but it has already achieved so much by becoming half full, and the hope is that it will continue to fill until it is full.

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Re: What-if 0006: Glass Half Empty

Postby Diadem » Tue Aug 07, 2012 6:40 pm UTC

Qaanol wrote:Atmospheric pressure at sea level is over 14 pounds per square inch. That means if your body has a cross-sectional area of 1 square foot, the air is pressing down on you with about 1 ton of force. Luckily it is also pressing up on you with that same 1 ton of force, and in all directions on all exposed parts of your body, with that 14 pounds per square inch. Air pressure is strong.

Say the vacuum region in the water glass is cylindrical with a diameter of about 5 cm (2 inches). Then the upward “suction” force on the glass is about 200 Newtons. The glass probably weighs around 100 grams, so it accelerates upward at 2000 m/s2, or about 200 times more quickly than gravity pulls it downward.

Of course, the glass only has about 2 cm to rise before it runs out of vacuum. The impact from the water will go almost entirely into fracturing the glass, and will barely slow down the cylindrical walls of the glass at all, which end up going about 9 m/s (about 20 mph). That means the glass walls would rise about 4m (13 feet), but they hit the ceiling after about 1.5m while still traveling 7.2 m/s (about 16 mph).

I suspect Randall used slightly different measurements than I did, but the results are comparable. The glass ring will hit the ceiling with plenty of speed to shatter.

But this only works for a glass that is a true cylinder. The glasses that Randall drew are, but most aren't. Most glasses are wider at the top than at the bottom. This means that if the glass starts rising upwards, it will have to push water out of the way. But the water is trying to move down. It would fundamentally alter the picture. Will the glass rise at all in this case?

Also, why don't the sides of the glass collapse inwards? Can the average glass withstand that much pressure?
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Re: What-if 0006: Glass Half Empty

Postby daridiu » Tue Aug 07, 2012 7:19 pm UTC

I'm not sure whether the glass would break.
Take a 200 mL glass filled with 100mL of vacuum and 100mL of water, the energy released just before most of the water hits the bottom is 105Pa (Atmospheric pressure) * 10-4m3 (Vacuum volume) = 10J. It has been shown (see http://www.sciencedirect.com/science/article/pii/S1752928X08001728) that an empty glass bottle needs 40J to break, so we can expect that the energy required by the glass to break to be several dozens of joules. So the glass might not break, or the breaking of the glass could use a significant part of the available energy.

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Re: What-if 0006: Glass Half Empty

Postby dotancohen » Tue Aug 07, 2012 8:21 pm UTC

Actually, none of the glasses were half empty until the left one broke. They were all half-full.

Empty:0% content
Full: 100% content

Half empty: 0/2 = 0% content
Half full: 100/2 = 50% content

Only the broken glass, which held no content, was half empty.

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Re: What-if 0006: Glass Half Empty

Postby Jamaican Castle » Tue Aug 07, 2012 9:02 pm UTC

So here's what I don't get: in the glass on the left, with the vacuum on the bottom, why doesn't the water fall into the empty space? I get that it doesn't expand the way a gas would, but it ought to be pulled down by simple gravity - it's not like being filled with air where there's a pressure acting against it.

I suppose it could be that, given the tiny timescale here, by the time that's gotten started the glass is already on its way up, and the falling from gravity is lost in the general collision-related mayhem.

Also, I'm quite certain the physicists are going to be far too fascinated to duck, per XKCD 242.

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Re: What-if 0006: Glass Half Empty

Postby Whizbang » Tue Aug 07, 2012 9:10 pm UTC

I thought the same thing, Jamaican Castle, but if you look at the pictures, the water does move downward in each "frame". Like you said, though, there isn't enough time for it to fall far.

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Re: What-if 0006: Glass Half Empty

Postby Роберт » Tue Aug 07, 2012 9:16 pm UTC

Diadem wrote:Also, why don't the sides of the glass collapse inwards? Can the average glass withstand that much pressure?

Are you familiar with how mercury barometers work?
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Re: What-if 0006: Glass Half Empty

Postby Ignitus » Tue Aug 07, 2012 9:42 pm UTC

Actually, none of the glasses were half empty until the left one broke. They were all half-full.

Empty:0% content
Full: 100% content

Half empty: 0%/2 = 0% content
Half full: 100%/2 = 50% content

Only the broken glass, which held no content, was half empty.



I find this definition sound and hard to dispute.

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Re: What-if 0006: Glass Half Empty

Postby Dark Avorian » Tue Aug 07, 2012 10:01 pm UTC

I was hoping he would talk about what would happen if you packed enough water into the glass that by some naive non quantum interpretation of subatomic particle dimensions the glass would actually be half full
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Re: What-if 0006: Glass Half Empty

Postby Max™ » Tue Aug 07, 2012 10:35 pm UTC

Dark Avorian wrote:I was hoping he would talk about what would happen if you packed enough water into the glass that by some naive non quantum interpretation of subatomic particle dimensions the glass would actually be half full

I wouldn't want to be around to find out that one.

As was pointed out above, 14 lbs of air pressure pushing down on the water and in/up on the sloped sides of the glass when the vacuum is suddenly placed there.

Take a plastic bottle up on top of a mountain, open it up and dump out whatever is in it, close it tightly, bring it down to sea level:
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Re: What-if 0006: Glass Half Empty

Postby not baby Newt » Tue Aug 07, 2012 10:44 pm UTC

Роберт wrote:
Diadem wrote:Also, why don't the sides of the glass collapse inwards? Can the average glass withstand that much pressure?

Are you familiar with how mercury barometers work?

Those have much smaller diameter, doesn't mean all glass items can withstand 1 atm.

But perhaps the flat bottom is more fragile, either breaking apart or being sheared loose from the sides and pushed up whole.

I'm guessing you can find glasses that fit either scenario.

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Re: What-if 0006: Glass Half Empty

Postby Max™ » Tue Aug 07, 2012 11:56 pm UTC

The idea is that the vacuum is effectively pulling up on the glass at some fraction of atmospheric pressure (14 psi) while pulling the water down with gravity, and water doesn't compress so the impact is like a good kung fu punch, all the energy is delivered into the bottom of the glass in a very short period of time, enough to slow the sides, but not stop them.
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Re: What-if 0006: Glass Half Empty

Postby Quicksilver » Wed Aug 08, 2012 12:48 am UTC

Attitudes are meaningless, Randall; you've still got glass in your face.

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Re: What-if 0006: Glass Half Empty

Postby not baby Newt » Wed Aug 08, 2012 12:51 am UTC

Max: Sure, that explanation is probably correct. I'm not explaining the tangent I'm interested in well.

Perhaps I should ask: how many atmospheres outside is needed to break the glass before the water impact and which part would break first?

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Re: What-if 0006: Glass Half Empty

Postby wbeaty » Wed Aug 08, 2012 1:29 am UTC

peewee_RotA wrote:I think the glass lifting itself is debatable, however.


Imagine a spring-powered gun, where the spring provides 100lb 450nt force, and the bullet is a 0.5LB 0.3KG hunk of water.

What's the muzzle velocity? Will the gun fly backwards when fired? Will it launch itself upwards if fired down (assume the gun masses 0.5KG)?

About energy expended on doing work to crack the glass: it depends on the glass strength, but empirically the glass will just be on the threshold of cracking if the vacuum pocket is 5mm wide, YMMV. Right at threshold, the cracked glass bottom and the water drop passively downward. A wider vacuum pocket will provide extra KE above that absorbed by glass-smashing, and should actively drive the glass bottom and the water violently down. With enough cms of vacuum pocket, just the water alone could punch through a wooden tabletop.
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Re: What-if 0006: Glass Half Empty

Postby VectorZero » Wed Aug 08, 2012 1:39 am UTC

What's up with this glass? Excuse me? Excuse me? This is my glass? I don't think so. My glass was full! And it was a bigger glass!
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Re: What-if 0006: Glass Half Empty

Postby wbeaty » Wed Aug 08, 2012 1:50 am UTC

Qaanol wrote:The impact from the water will go almost entirely into fracturing the glass.


Not true. Brief experimentation with beer bottles and mallets shows that we don't need a vacuum pocket many-cms thick in order for the water to fracture the glass bottom. Crude estimate from experience: 1/2cm pocket can do it. Ah, that's right, there's the Time Warp episode which shows us the necessary vacuum pocket width... http://www.youtube.com/watch?v=cOeNxkksruo&t=1m45s. That's to part the glass and drop the bottom out, with no remaining momentum dumped into the glass cylinder.

Any wider than that, and the remaining KE of the moving water will leave the glass disk+water flying down and the glass cylinder flying upwards. Hmmm, estimate Kilojoules?

Possible question: with 50mm of vacuum pocket, would the "muzzle velocity" of the glass/water slug be enough to punch right through a kitchen table, and also fling/explode the glass cylinder against the ceiling so the shrapnel flies mostly radially?

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Re: What-if 0006: Glass Half Empty

Postby Pfhorrest » Wed Aug 08, 2012 2:21 am UTC

Dark Avorian wrote:I was hoping he would talk about what would happen if you packed enough water into the glass that by some naive non quantum interpretation of subatomic particle dimensions the glass would actually be half full

You could have a glass that was half true vacuum and half matter of any sort compressed exactly down to its Schwarzchild radius. Of course by that point you're basically at "what if a small black hole suddenly appeared on the surface of the Earth"; it being in a glass and accompanied by a small pocket of vacuum are pretty much negligible factors by then; considering that it would take a mass at least an order of magnitude larger than the Earth to have a Schwarzchild radius large enough to fill half a glass.

Although, I imagine there might be something interesting to say about starting the arrangement of matter in such a non-spherical shape as to cleanly fill half a normal drinking glass (whereas under normal circumstances it would be decidedly spherical by the time it got that compressed), but that would be something interesting to physicists... alien physicists, a long ways away. Because one way or another Earth is very quickly toast.

Long story short: you should always want to keep your glass far, far from anything even approaching half full. All that empty space is there for your safety.
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Re: What-if 0006: Glass Half Empty

Postby Max™ » Wed Aug 08, 2012 2:51 am UTC

Pfhorrest wrote:
Dark Avorian wrote:I was hoping he would talk about what would happen if you packed enough water into the glass that by some naive non quantum interpretation of subatomic particle dimensions the glass would actually be half full

You could have a glass that was half true vacuum and half matter of any sort compressed exactly down to its Schwarzchild radius. Of course by that point you're basically at "what if a small black hole suddenly appeared on the surface of the Earth"; it being in a glass and accompanied by a small pocket of vacuum are pretty much negligible factors by then; considering that it would take a mass at least an order of magnitude larger than the Earth to have a Schwarzchild radius large enough to fill half a glass.

Although, I imagine there might be something interesting to say about starting the arrangement of matter in such a non-spherical shape as to cleanly fill half a normal drinking glass (whereas under normal circumstances it would be decidedly spherical by the time it got that compressed), but that would be something interesting to physicists... alien physicists, a long ways away. Because one way or another Earth is very quickly toast.

Long story short: you should always want to keep your glass far, far from anything even approaching half full. All that empty space is there for your safety.

Yeah, I was thinking best case, degenerate neutron star materials, worst case, black hole... not what I want on the table in front of me.
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whateveries
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Re: What-if 0006: Glass Half Empty

Postby whateveries » Wed Aug 08, 2012 3:52 am UTC

with respect to glass1,water over vacuum. I am not sure how it would compare to the 'college' trick with the bottom being smashed out of the bottle, see the liquid vs gas vs sudden vacuum occurs in a closed system with a finite amount of material to play with (comparitve to the volume of the bottle) In The case of glass 1, we have an open system, with an infinite amount of material to play with (comparitive to the volume of the glass), what happens when the water starts to move toward the vacuum, wouldn't the sudden drop create a secondry vacuum above it (and possibly a sudden vacuum beneath the glass, were it to suddenly rise), thus drawing in the gas above it (and below it), but also drawing itself back upwards (and downwards), all the while gravity is trying to push the liquid to the bottom of the glass, and the boiling liquid (i.e Gas) is trying to get to the top of the glass, all the while the liquid is dropping in temperature rapidly from boiling on two faces, with the microcurrents being generated by the difference in the two interface temperatures to the core of the water plug, along with the movement of the gas stream, I would suspect the water might part and the atmosphere would rush in to fill the vacuum, before any super neat flying glass tricks panned out to much more than a splashy gloop and wobble.

but then I am an optimist.

what we need is someone with access to a physics modelling software package to model this.
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Re: What-if 0006: Glass Half Empty

Postby Bloopy » Wed Aug 08, 2012 7:42 am UTC

Yoduh wrote:optimists will see the glass half full because they believe the glass will eventually be filled, to be whole, to reach a state greater than the one it's currently in. It WAS empty which was an optimist would say is an awful state to be in, but it has already achieved so much by becoming half full, and the hope is that it will continue to fill until it is full.

Optimists see the glass half full because they will enjoy drinking that half, even though it's only a half. They're not focusing on the negative aspect (the empty half).


I'd say it's the polymath who sees the glass as both half full and half empty, wants to understand everything about the glass, and envisions all of the possibilities of the glass. Including what would happen if one half was suddenly a vacuum!

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Re: What-if 0006: Glass Half Empty

Postby The Moomin » Wed Aug 08, 2012 9:14 am UTC

In Star Trek IV: The Voyage Home, didn't they teleport whales from the ocean into a tank? Wouldn't that have caused an instantaneous vacuum within the ocean and what effects would that have caused?

Also, aren't they causing vaccums in the air every time they teleport around? Are the shockwaves caused by this leaving a trail of destruction wherever they go?
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Re: What-if 0006: Glass Half Empty

Postby carolineee » Wed Aug 08, 2012 9:44 am UTC

The Moomin wrote:In Star Trek IV: The Voyage Home, didn't they teleport whales from the ocean into a tank? Wouldn't that have caused an instantaneous vacuum within the ocean and what effects would that have caused?

Also, aren't they causing vaccums in the air every time they teleport around? Are the shockwaves caused by this leaving a trail of destruction wherever they go?

I always assumed the body would just switch places with the air (or water or whatever) it replaces. That could be a problem for the teleporter crew though, if they teleport someone or something into a toxic environment.


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