back to article Made for each other: liquid nitrogen and 1,500 ping-pong balls

It's the rare scientific mind that has the pure intellectual chutzpah to tackle a problem that has troubled boffinry since the discovery of cryogenics – namely, "What happens if you combine liquid nitrogen with 1,500 ping-pong balls?" C'mon, don't tell The Reg that question hasn't crossed your mind. It hasn't? Well, then you …

COMMENTS

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  1. Aaron Em
    Happy

    Sidebar ad: "Play ping-pong whenever you want, all by yourself!"

    Guess so...

    1. The Man Who Fell To Earth Silver badge
      FAIL

      Nothing new here, move along

      This trick is very very old one for folks trained in the field of Low Temperature Physics. I remember seeing this done in the 1970's while in graduate school, and the person who did it was in his 60's and claimed to have first seen it when he was in graduate school.

      1. h4rm0ny

        Re: Nothing new here, move along

        I know you think your comment is more important than other people's, but just picking the first post and making an unconnected reply so you can ride higher than everyone else's posts... don't do that.

  2. MR J
    Trollface

    Amazing

    The things you can afford to do when you charge 50 kids £9,000 a year.

    1. Voland's right hand Silver badge
      Devil

      Re: Amazing

      More. Look carefully at the audience. Zoom into fullscreen if you have to. You will see that these are not the 9k paying students you are looking for.

      This looks like a circus run for the entertainment of candidate foreign students during an open day tour. If memory serves me right you are allowed to charge these more than the base 9k fee which locals have to pay.

    2. Anonymous Coward
      Anonymous Coward

      Re: Amazing

      The kids paying the £9k/year (that a lot of these kids still don't seem to have realised they only pay back long AFTER they use the service) who get the direct benefit of the education and increased lifetime financial earnings makes more sense to me than a cleaner on £15k/year struggling to make ends meet paying their £9k for them.

      Sure, if you want 10% of the population to go to Uni society can afford it. At 50%, it's not sustainable, and those who benefit should pay more of a contribution.

      I'm sorry if I can't bring myself to weep for these kids.

      1. Anonymous Coward
        Anonymous Coward

        @AC 7:28 and upvoters

        No, you can't bring yourself to weep for these kids. You're rich enough for your kids to be able to go whaterver the fee and it's the only the plebs and chavs that will be put off going by the 9 grand a year price tag.

        An educated workforce obviously does nothing for the economy as a whole, and the last thing we need is a group of working class oiks getting above themselves because they have an "education"....

        1. Anonymous Coward
          Anonymous Coward

          Re: @AC 7:28 and upvoters

          The way these new rules actually work means that many of them will never actually pay back as much as I will, as I was under the original Labour rules which were "You WILL pay the whole lot back unless you die first. And no, you still owe us the money even if you're bankrupt."

          Thus the boundaries and repayment rates meant that some student would be paying the interest on the student loan for their entire life.

          It got changed a couple of years later to "We'll write off the remainder after 25 years", but the boundaries still meant that many would pay back more than the original loan amount.

          The new rules are writing off after 30 years, but now the boundaries are such that the national average pays back £33k total on a loan of £27k, and most of those below average earnings will have paid back less than they borrowed before the write-off.*

          So how exactly does that loan put them off?

          Unless of course it's because they can't do the maths, in which case they probably shouldn't be doing a science, maths or engineering degree anyway, so job done at promoting those!

          * Source: BBC Student Finance

          1. Anonymous Coward
            Anonymous Coward

            Re: @AC 7:28 and upvoters

            Yep, just been working this out myself. For each student that doesn't become a "high earner", i.e. 60K (*) plus before they are 40, the government (thats us) will end up spending more than they (we) would by paying the fees up-front. Mind you the private companies involved will do quite well out of it, so thats nice.

            (*) excl inflation

        2. Shane 4

          Re: @AC 7:28 and upvoters

          Already happening at my work place. They come straight out of Uni and end up same place I am working as there isn't any other jobs. But once here they seem to think they are better because they have a bit of paper, I make sure I put them back in their place quick smart. Not only are they lazy and weak but can't even do basic problem solving on the job. People must realise we can't all be doctors otherwise everything we have in society will crumble. Uni is just a sham to take people's money and keep it looking like governments are doing something. What is the bet there will probably be uni degrees for cleaning sooner or later! Laugh all you like now but there are already uni courses for topics that clearly don't need it.

          Here is just a sample of some of the most rediculous, But there are many many others.

          http://www.toptenz.net/to-10-useless-college-classes-degrees.php

      2. sabroni Silver badge

        Re: Amazing

        The problem with your argument is how you go from 50% to 10%. You seem to think that the way to restrict the numbers is to make sure that only the rich can afford to go to university. I would argue that it's more important to encourage the less well off to get a degree, as their prospects are often worse.

        1. Anonymous Coward
          Anonymous Coward

          Re: Amazing

          I think a lot of degrees need to be revoked if future candidates are to be in with a chance.

          If you're over 40 your degree should be revoked. For your own good

          1. Anonymous Coward
            Anonymous Coward

            Re: Amazing

            and actually if you're under 30 no degree for you either.

            in fact i think no degrees for anyone. fuck em. fuck em.

        2. Ken Hagan Gold badge

          @Sabroni

          " You seem to think that the way to restrict the numbers is to make sure that only the rich can afford to go to university."

          I feel I have to butt in here and say that didn't get that sentiment from the OP. On the contrary, they seemed to be bemoaning the fact that we had gone from 10 to 50 and *as a consequence* had to ditch the previous system.

        3. jason 7

          Re: Amazing

          All we have to do is tell the retards in the HR depts in the UK that 90% of jobs do not require a degree full stop.

          1. Anonymous Coward
            Anonymous Coward

            Re: Amazing

            just my 2p worth....

            It used to anoy the hell out of me that in the past, when kids who's parents were on low incomes and all the tuition fees were paid for by the state and recived grants to live on for the time they were at uni, only to piss off overseas and take on well paid jobs and not paying uk tax repaying the investment the state made in them.....

            with student loans, at least they are investing in their own futures.

            The student loan system will if anything stop the masses of people doing nonsense courses that never leave to a job, but they see it as better than getting a job in the first place.

            If anything, I think the state should write off a % of the loan for each year they are paying tax in the UK so that people can be out of debt for their studies sooner.

            It does not bother me or my daughter that she is likely to be 40k+in debt by the time she finishes uni. she will be well qualified as a dentist and be earning more than that each year

          2. Anonymous Coward
            Anonymous Coward

            Re: Amazing

            No, all we have to do is fire all the retards in the HR depts. There, fixed it for you.

            1. Esskay
              WTF?

              Ahhhh... The Internet...

              Where poitical articles' comments are filled with childish name calling, and an article for a youtube video of an explosion results in a page of debate regarding the state of tertiary education.

        4. Goat Jam

          Rich vs Poor

          I would have thought that the most scholastically gifted would be the best ones to go through University.

          It should have nothing to do with how rich daddy is.

          Having a bunch of rich knuckleheads coasting through a soft arts degree on daddies dollar is no better or worse than having a bunch of poor knuckleheads coasting through a soft arts degree on the taxpayers dollar, except for the fact that I don't have to pay for daddies little princess I guess.

        5. I think so I am?
          Mushroom

          Re: Amazing

          What you need to do is educated everyone to a level, then subsides University courses that produce graduates in a needed fields.

          i.e. take medicine or engineering and the course is free - take media studies, sport science or drama charge £15k a year. Then when you have enough engineers and doctors start raising the fees. But the chances are you'll never have enough doctors an engineers; the rich will still send their kids to University to do History and modern art but we wont be subsiding muppet's who are just putting off working in a call center for another 3-4 years so they can piss it up.

          1. jason 7

            Re: Amazing

            I agree, courses that will put money on the table - Free of charge. Maybe charge a deposit fee repayable after staying resident in the UK for 3- 5 years after graduation.

            Courses that are a waste of life - Charge the earth.

      3. Anonymous Coward
        Anonymous Coward

        Re: Amazing

        "Sure, if you want 10% of the population to go to Uni society can afford it. At 50%, it's not sustainable, and those who benefit should pay more of a contribution."

        I'd rather we as taxpayers paid for that 10% to go to university assuming that they go on merit alone (which I'd admit is hard to enforce). The current system of churning out tens of thousands of rubbish graduates that can barely spell their own names and have zero interest in their subjects is no use.

      4. paul clinch

        Re: Amazing

        Perhaps they do realise they being charged interest on the loan from the time they get the money.

    3. Tom 7 Silver badge

      Re: Amazing

      This probably costs less than the adobe typesetting program for publishing the lecturers compulsory book in hardback form, which will immediately be out of date as any students that actually buy a copy will be performing the task of proofreading.

    4. keithpeter

      Re: Amazing

      Liquid Nitrogen is pretty cheap - pence per litre for the electricity. A few pingpong balls don't cost much. We have the video. Lighten up...

  3. The Alpha Klutz

    i would do this in a crowded area

    then when everyone suddenly stops walking because of the sudden ping pong balls slapping them in the face, i will take the opportunity to become extremely aggressive and hit people with a bog brush; which is painful and humiliating.

    1. OrsonX

      Re: i would do this in a crowded area

      why not go all the way and add some nails?

  4. William Boyle
    Thumb Up

    Great!

    This reminds me of some of the experiments in freshman physics I had with Frank Oppenheimer at the University of Colorado in 1966-67! As we would say at Dulwich College (SE London where I went in 62-63), well bowled! :-)

    1. Phil O'Sophical Silver badge
      Thumb Up

      Re: Great!

      I still remember, as a teenager, being taken by a friend's Dad to an afternoon of similar chemical high jinks run at the local university. I still find physics and chemistry fascinating.

  5. Eddy Ito Silver badge

    Great contest

    Guess how many ping pong balls are in this trash bin? Wait for it.

    BOOM!

    None.

  6. jon 72
    Devil

    Thankyou all for coming..

    before you go give us a hand to pick them up!

    1. Anonymous Coward
      Happy

      Re: Thankyou all for coming..

      Hey! Look! Souveniers!

  7. Uwe Dippel
    Thumb Down

    That's learning of today (the future)?

    While I do think that learning should not be dreary, and neither accompanied by whipping and memorizing, I also am unconvinced that a 5 minute-stunt at an expense, even a relatively low one, is anything but a stunt, a marketing exercise by this good university.

    Instruction this is not. Explanations given immediately before, seemingly to unprepared students, no calculation done. Is this the tertiary education of the nouveau rich; entertainment to get them kids off their iPhone5 for some minutes with a bang? Silly laughter, exit, and the assistants cleaning the floor nicely from glass debris and collecting 1500 ping-pong balls. Thank you.

    1. Anonymous Coward
      Paris Hilton

      Re: That's learning of today (the future)?

      You must have a really interesting life...

      Paris... because she likes a good bang.

    2. Mystic Megabyte Silver badge
      FAIL

      Re: That's learning of today (the future)?

      Glass debris? I think you'll find that it was a plastic bottle.

    3. DF118

      Re: That's learning of today (the future)?

      Cheers Buzz Killington, youre really doing a great job of reminding us how fucking boring and worthy 99% of everything is. Keep up the good work.

    4. Anonymous Coward
      Anonymous Coward

      Re: That's learning of today (the future)?

      Lets see some of what the experiment demonstrated:

      Liquid / gas transition. materials strength, thermodynamics, Newtonian physics and much more.

      That one demonstration can provide hours of lectures across multiple fields. Instead of dreary diagrams trying to get a point across they can refer directly to the demonstration, something that the students will vividly remember and something that takes it out of the realms of classroom theory into a real world example.

      You are also confusing laboratory work with a demonstration. If this was laboratory work then the students themselves would be setting up the experiment and the instruments to take the measurements. Thinking about it, there's another lecture for you. He can ask the students how they would set it up as an experiment, what they would measure and how, what it would tell them etc...

      It is pity that your lack of imagination and your obvious prejudices limit you so much.

      1. Charles 9 Silver badge

        Re: That's learning of today (the future)?

        There are some studies that point out that the dreary approach (rote memorization and lengthy practice drills) actually yields better long-term results. I don't know why, but I think it's because that combined with a very high competitive bar (I think they were comparing Japan in this case, which tends to foster mutual competition) tends to make the students focus, and focused learning tends to stick better because there's a motivation behind it..

        1. Antidisestablishmentarianist

          Re: That's learning of today (the future)?

          Well that education style doesn't get you employed in my industry. Whilst it may make you an absolute ace should the problem space fit inside the box you were taught, as soon as you have to think outside that box, epic fail.

        2. keithpeter
          Windows

          Re: That's learning of today (the future)?

          Japan... ah, that would be the country that is offering very good jobs to ex pat US and UK academics in 'creativity' teaching...

          My point being 'long term results' on what test?

    5. Mark 65 Silver badge

      Re: That's learning of today (the future)?

      I think you'll find it is useful in demonstrating the amount of force that can be generated by a liquid evaporating (albeit one that does so at -196C). Most would not have realised that this level could occur from such a small amount of liquid. That bin bounces a long way up.

      1. Mike Richards Silver badge

        Re: That's learning of today (the future)?

        It can also be used to show why it's not a good idea to have a beachfront property in Pompeii when gas comes out of solution in a nearby magma chamber.

    6. OrsonX

      @Uwe

      It is education.

      It makes them ask the most important question of all:

      WHY?

    7. Anonymous Coward
      Anonymous Coward

      Re: That's learning of today (the future)?

      Perhaps you don't know of the Purdue University "Light a barbecue with liquid oxygen" video which went viral on the early public Internet? It's said it significantly increased applicants for science courses at Purdue. This is a good example of low-cost marketing. True. But whoever said that universities don't need to do it?

      I went to completely the wrong university for what I wanted to do (Cambridge, as it happened) because in my day there was too little information about different universities and different courses. With so much information nowadays, stunts like this may cause students to read up on a university they would not otherwise have considered, that may be better suited to their interests and needs. So don't knock it.

    8. Chris Beach
      FAIL

      Re: That's learning of today (the future)?

      Unless you were at his lectures before and after this video was taken, how can you say that? You've no idea what calculations or prep work where done.

      It's a YouTube video, it's the exciting bit, the rest doesn't tend to make good viewing.

    9. No, I will not fix your computer
      Thumb Up

      Re: That's learning of today (the future)?

      Learning how to learn is the most important lesson, sometimes you can do this with a bang rather than a book, if everybody was the same then teachers would only need to teach one way.

      We are not all the same, this experiment may well have enthralled one student enough to study physics, if this is the case that's *enough* to make the whole exercise it, maybe it's those cool things which excites people enough to ask "what if".

  8. Destroy All Monsters Silver badge
    Thumb Up

    It's like an episode of XKCD

    In my classes, the booms were all accidental...

    1. This post has been deleted by its author

    2. Anonymous Coward
      Anonymous Coward

      Re: It's like an episode of XKCD

      Not in our classes they weren't. One of the chemistry teachers was fond of making water by lighting balloons filled with a 2:1 mixture of hydrogen and oxygen. Used to wake up those sleeping through maths in the classrooms below the lab.

      We had accidental ones too though. Mine involved a probable toluene residue from the previous day in a test tube used for a nitration experiment. Oops :)

      1. Anonymous Coward
        Anonymous Coward

        Re: It's like an episode of XKCD

        This stuff has a long history. I have a 1910 chemistry textbook which describes and experiment in which a long lead tube is filled with a mixture of carbon monoxide and oxygen. At one end is a boiling tube in a large shield. The other end is sealed and a spark generated. Of course it has a serious purpose: to show the speed of flame propagation in a gas/oxygen mixture. The reduction of the boiling tube to sand grains is just a little added flourish.

  9. frank ly Silver badge

    Interesting point

    Notice that the bin lifted into the air in a quite dramatic way. Perhaps the students could be set the task of explaining why that happened. It's supposed to be about learning isn't it?

    1. Neil Barnes Silver badge

      Re: Interesting point

      I was wondering about that myself.

      The reaction from the explosion shoves the nitrogen and the balls out and up; that ought to push the bin down. I hypothesise flex in the bottom of the bin, but I'm not at all certain if that adequately explains it. Another thought is that there is a mechanical coupling between the balls and the bin, or perhaps a hole is blown in the bottom of the bin.

      1. Vic

        Re: Interesting point

        > I hypothesise flex in the bottom of the bin

        ...Or perhaps it was on a wooden floor which is not infintely inelastic.

        Vic.

        1. Craigo
          Boffin

          Re: Interesting point

          I would guess that as the Nitrogen returning to a gas expands and, its weight at a given volume and pressure reduces. Having disposed of the rest of the contents of the bin in the expansion, perhaps the bin becomes lighter than air and floats for a brief second before mixing with air and sinking.

          But then, I'm just an IT bod..

    2. Andus McCoatover
      Windows

      Re: Interesting point

      Wondered also. Would the sudden outflow of gas produce a vaccum in the bin? But, I think flexing of the base might explain it also, but I didn't notice flexing of the sides...

      1. Stoneshop Silver badge
        Boffin

        Re: Interesting point

        Of course, there's an XKCD for that: http://what-if.xkcd.com/6/ (the lefthand glass)

        1. Anonymous Coward
          Anonymous Coward

          Forget the XKCD example

          There's a vacuum involved. There is no vacuum here.

          Seems rather more likely to me that the force of the explosion pushes the centre of the base of the bin outwards by a small amount; enough to impart an upwards motion to the rest of the bin. I doubt the floor is elastic enough to provide sufficient force if the bin itself is totally rigid.

          A similar experiment (preferably one with a more powerful boom) in a metal bin might help demonstrate this in a fittingly graphic manner.

          1. Stoneshop Silver badge
            Boffin

            Re: Forget the XKCD example

            It's not the vacuum, it's the shockwaves

    3. Phil O'Sophical Silver badge
      Boffin

      Re: Interesting point

      My guess is that's the same physics as described here, but with a less tricky starting condition.

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

  10. Velv Silver badge
    Boffin

    Task for Rik Myslewski to go and ask the good professor and publish the answer here on El Reg.

    Just out of curiosity, why is it a Reg correspondent in San Francisco who is publishing, and not a UK correspondent? We're they all in the pub?

    1. Anonymous Coward
      Pint

      YouTube

      Rik gets paid to watch YouTube videos...and write about them. He just picks the ones from UKGBNI because the editors are more likely to approve them.

      Cheers! Rik.

  11. IHateWearingATie
    Thumb Up

    Bah humbug to all the killjoys...

    ... one of the benefits for being a professor has to be making things go bang occasionally, just for the hell of it.

  12. Mark Wilson
    Thumb Up

    Lessons you remember

    These are lessons those guys will remember, not the sat in a classroom going through dreary powerpoints or sat doing calculations. The lessons I remember from school are things like this. Magnesium + iodine, burning through an asbestos mat into the school long jump pit was one I really remember. Barely remember any of my computing lessons though even though that is my field.

    Oh and I suspect this was a lesson given to school kids not university students, in order to encourage them to go to university.

    1. Anonymous Coward
      Anonymous Coward

      Re: Lessons you remember

      Francium in water is my science memory from school. :-)

      1. Anonymous Coward
        Anonymous Coward

        Re: Lessons you remember

        Francium in water is my science memory from school. :-)

        Oh, someone had to make me fetch the grumpy pedant hat.

        You did not see francium in water at school. No-one will have seen francium in water anywhere. No-one has even seen macroscopic quantities of francium, even in a research lab. You will perhaps have seen videos of caesium or rubidium in water, and probably have seen potassium and sodium in water first hand.

        1. Michael Dunn
          Coat

          Re: Lessons you remember

          Hey! Francium wasn't invented when I was at school, the best we got was potassium.

          (Lab coat, of course.)

      2. No, I will not fix your computer
        FAIL

        Re: Lessons you remember

        I won't down vote your for it as it's probably just misrememberd, but francium is so astoundingly rare no teacher would have it, let alone just to chuck it in some water for the kids, it's also very radioactive (with a short half life).

        If it was enthusiatic, it was probably potassium.

    2. Justin Forder

      Re: Lessons you remember

      Thermite demo on the front bench resulting in droplets of molten iron being embedded in the chemistry lab ceiling is the one that sticks in my mind...

      Here's another liquid nitrogen/water/dustbin experiment, this time with rubber ducks:

      http://www.wired.com/wiredscience/2012/05/exploding-liquid-nitrogen-where-does-the-energy-come-from/

    3. Mike Flugennock
      Pint

      Re: Lessons you remember

      ...The lessons I remember from school are things like this. Magnesium + iodine, burning through an asbestos mat into the school long jump pit was one I really remember...

      I also remember big fun with sticks of magnesium in high school. An experiment called for it, and the teacher brought it in, packed in gel in metal casks, explaining why this was necessary to keep the magnesium from contacting air or water until ready, telling us the story of what happened to a kid who tried to sneak some out in his pants pocket.

      It wasn't two hours later that a loud bang was heard echoing from a boys' bathroom in the science wing, quickly followed by a teacher's voice shouting "come back here, you!"

      Oh and I suspect this was a lesson given to school kids not university students, in order to encourage them to go to university.

      This is possibly the most entertaining use of ping-pong balls in the name of science since I saw that old Disney movie Our Friend, The Atom in the third grade.

      A cold one for the professor.

      1. Andrew Norton

        Re: Lessons you remember

        We had similar after a 1st year class on the reactivity series.

        half the class nicked either magnesium ribbon, or in one case, a chunk of calcium.

        Next class was swimming, and guess where all the stuff ended up...

        Yep the bottom of the school swimming pool

      2. John Hughes
        Mushroom

        Re: Lessons you remember

        "also remember big fun with sticks of magnesium in high school. An experiment called for it, and the teacher brought it in, packed in gel in metal casks, explaining why this was necessary to keep the magnesium from contacting air or water until ready, telling us the story of what happened to a kid who tried to sneak some out in his pants pocket."

        Not magnesium.

        Sodium, potassium or lithium probably.

    4. bitten
      Mushroom

      Re: Lessons you remember

      I got tinnitus, and I don't even have to remember. I was surprised to see that the bottle did not become too brittle and explosed within a second.

    5. No, I will not fix your computer
      Thumb Up

      Re: Lessons you remember

      The talk I went to the Uni for (while still at school) involved a lecturer telling us that he's not allowed to buy liquid oxygen, so he produces his own, setting fire to digestive biscuits dipped in oxygen whizzing around like catherine wheels.

      In chemistry we made cordite, different types of thermite (one from plaster), fuming nitric acid, iodoform, it put things in context, made me ask "why?" and boring things (like charge on the electron) became part of the big puzzle, an became interesting.

  13. Stuart Halliday
    Thumb Up

    Plastic bottom of bin gets forced down so it contacts the floor and jumps up. Pretty basic stuff.

    1. bitten

      Nope, air pressure. The moving ping pong balls suck the bin upwards.

      1. Charles 9 Silver badge

        Not, it's the bottom of the bin, inflated momentarily by the explosively-expanding gas (note that the bin is thing plastic, not more-rigid metal). The balls are being forced out of the can by the nitrogen gas, which is taking the balls' place in the can, so no vacuum is involved.

  14. Pete 2 Silver badge

    Good training opportunity

    ... after all, someone has to clear up those PP balls

  15. Andrew Norton
    Boffin

    Not a patch on salthouse

    I was lucky to attend one of Dr John Salthouse's lectures at Salford Uni in 98. He's been described as a pyromanic with a chemistry degree and I'd concur. Even my school's department head was in awe and he was also a pyro (and the my school left one lab unrefurbished for him, on the basis of it having survived that teachers experiments since the 60s, it would carry on - notably a 3rd floor room, with windows on 3 sides and it's own fire escape)

    I'm not saying some of the bangs were loud, but we were in the biggest lecture theatre at Salford's chem dept, and one bang broke a ceiling tile and dropped it (right at the back, up the aisle from the bang, clearly an acoustic concentration with the aisle funneling and the back wall echo) an impressive feat I'm sure you'll agree. Sometimes I wonder if I should have done Chemistry, instead of Robotics as my degree subject....

    1. David Gosnell

      Re: Not a patch on salthouse

      Ah yes, I came here to reminisce about Dr Salthouse also, having enjoyed a lecture of his circa 1987 (?) when he visited our secondary school and did various hairy things with liquid oxygen, oxyacetylene, hydrogen, digestive biscuits etc. Standard test for hydrogen being a squeaky pop from the test tube? Not when the test tube is six foot tall. Yes, we did have to break all safety regulations with the smoke alarms in our lecture theatre...

  16. sean.fr

    The gas and balls going up are rocketing the bin into the ground. Compressing the bin like a ball bouncing. When the bin flexs back it pushes off the floor.

  17. Tim 3

    I wish I'd seen this a few years ago...

    I was left unattended with some dry ice and a drinks bottle and made the same "experiment" minus the ping pong balls. I'd hypothesised the lid would would pop off and the sink would fill with cold water vapour. The bottle was placed in the sink wrapped with a wet cloth to warm it and catch the lid. The top of the sink was covered by a ceiling tile "just in case"...

    A few minutes later it hadn't gone off and I was treating it like a lit firework and ignoring it. There was a very loud pop, cloud of ceiling tile and some water vapour...but no sign of the bottle. It had shot straight up, turned the first tile to dust and left a perfect bottle shaped hole in the ceiling above. Don't try this at home.

    1. Anonymous Coward
      Anonymous Coward

      Re: I wish I'd seen this a few years ago...

      This is almost what happened with my first attempt at home beer making. Very stupidly, I put the half-fermented mixture into a glass bottle, put on the cap, and left it on a shelf in the garage (I was 15 at the time).

      A few days later there was a loud bang. On investigating, the base of the bottle had sheared off, causing the bottle to be sent vertically into the shelf above, which was only thin plywood and now had a bottle wedged half way through it.

  18. Anonymous Coward
    Anonymous Coward

    Professor Nicholas (Nick) Kurti?

    Isn't this vaguely the kind of thing that the late Oxford professor Nick Kurti (1908-1998) used to do, except (1) a lot of his experiments were edible (2) they were before the days of t'Internet and cameraphones (which is a shame).

    What's Oxford for these days, besides PPE and fund-raising?

  19. ISYS
    FAIL

    Spelling - See me!

    What is a Liter?

    1. Anonymous Coward
      Anonymous Coward

      Re: Spelling - See me!

      It's an American litre, which is only 4/5th of an Imperial litre.

      1. ISYS

        Re: Spelling - See me!

        Do you mean a metric litre?

  20. John Smith 19 Gold badge
    Thumb Up

    Now if only a lecturerer directory listed *this* sort of stuff...

    "Prone to blow stuff up.""

    or

    "Demos regularly exceed sound barrier in open air."

    Seriously this teaches many valuable lessons. Especially.

    1) Stuff does not work like a text book (the dustbin shouldn't jump, but it does). A *very* useful lesson to learn in our modern theory heavy, computer simulation loving world.

    2) This stuff can be dangerous *unless* you take precautions. It might technically be a demonstration of rapid expansion through flash boiling but it looks *remarkably* like an explosion.

    People usually decide to get into something because they see something and think "I want to be able to do that." All STEM education could do with a bit more of this.

    1. Charles 9 Silver badge

      Re: Now if only a lecturerer directory listed *this* sort of stuff...

      1) The dustbin jumped because most dustbins that size aren't flat or rigid at the bottom. They usually have a recess down there to reduce friction when you have to drag it. When the nitro blew, contained even momentarily by the ping pong balls, the pressure probably inflated the recess down there, causing it to push down and strike the floor at velocity, working like a downward-striking piston.

      2) A lot of things look remarkably like an explosion. Rapid combustion, for example. Explosion is a pretty vague term usually.

      1. John Smith 19 Gold badge
        Boffin

        Re: Now if only a lecturerer directory listed *this* sort of stuff...

        "1) The dustbin jumped because most dustbins that size aren't flat or rigid at the bottom. They usually have a recess down there to reduce friction when you have to drag it. When the nitro blew, contained even momentarily by the ping pong balls, the pressure probably inflated the recess down there, causing it to push down and strike the floor at velocity, working like a downward-striking piston."

        Highly *probable*. For proper science you'd need to devise experiments that prove or disprove the hypothesis. Which is also what a good demonstration is all about.

        "2) A lot of things look remarkably like an explosion. Rapid combustion, for example. Explosion is a pretty vague term usually."

        http://en.wikipedia.org/wiki/Deflagration_to_detonation_transition

        (Not got the time to dig out my standard textbook on this).

        As you will see the correct term is "detonation" and it's *qualitatively* different (> Mach 1 pressure effect Vs typically 10s of ms^-1 chemical) from combustion.

        A point which would probably be academic if you found yourself *inside* such a cloud.

    2. A J Stiles

      Re: Now if only a lecturerer directory listed *this* sort of stuff...

      Well, a good working definition of an explosion is "any rapid process, the final products of which take up significantly more space than the initial ingredients".

      Quickly heating a lot of liquid nitrogen above its boiling point inside a closed vessel made of a (now) brittle substance definitely qualifies under this definition.

  21. Slowhand
    Unhappy

    Shocking safety precautions

    As an ex-chemist with training in the industry (not university) I was shocked by the lackadasial handling of safety measures:

    1. Liquid nitrogen is handled with unprotected hands, although there are some heavy duty gloves lying on the table. When the professor removed the funnel he nearly did have an accident.

    2. No safety glasses worn by him or his assistents where liquid nitrogen and an explosion are involved.

    3. No protective clothing to protect his body, especially his naked arms under a short-sleeved shirt.

    Sad state of "teaching by example" in the universities.

    1. keithpeter
      Boffin

      Re: Shocking safety precautions

      Personally, I avoid cuffs when handling liquid nitrogen as I don't want drops caught between cuff and wrist. The odd small drop falling on my hand just boils off, getting a drop squashed under clothing causes a cold burn. I used to actually roll my sleeves up when pouring from dewar into thermos. I suppose you could cover up completely.

      Agree with funnel handling, those gloves should have been used, and agree with the safety specs - especially if there is liquid gas hanging about in open thermos flasks

    2. Steven Roper
      FAIL

      Re: Shocking safety precautions

      If you were really a chemist, you'd know about the Ledenfrost effect and that being the reason why you NEVER wear gloves or other clothing that can trap the liquid next to your skin when handling cryogenic liquids.

    3. Anonymous Coward
      Anonymous Coward

      Re: Shocking safety precautions

      I dare say you're one of those who require kids playing conkers to wear safety glasses and god help any circus performers... hard hat and safety boots before you get on the high wire...

      Someone showed me his big vat of nitrogen then stuck his hand in it to demonstrate that the instantly vapourised liquid formed an insulating layer of gaseous nitrogen around his hand so it emerged unscathed. I hasten to add it was a very brief immersion and, despite understanding the physics and despite having had a demonstration, I declined to try the same trick.

      1. Phil O'Sophical Silver badge
        Thumb Up

        Re: Shocking safety precautions

        You should have tried it, it's a really weird feeling having your fingers in boiling liquid. Almost like feathers, but not quite.

        1. keithpeter
          Boffin

          Re: Shocking safety precautions

          Yes, nice, but remember the insulating layer of N2 boiled off your skin does not last long...

      2. Michael Dunn
        Happy

        Re: Shocking safety precautions

        I fondly remember Professor Low (30's-40's) performing a similar trick with molten lead.

  22. Mage Silver badge
    Flame

    Replace Ping Pong balls with balls of charcoal or Coke

    And Liquid Nitrogen with Liquid Oxygen.

    Um... do it outside and stand further away ...

    1. Anonymous Coward
      Anonymous Coward

      Re: Replace Ping Pong balls with balls of charcoal or Coke

      Sir sir s/he's a terrorist sir.

      Can I have my reward now?

  23. J. Cook Silver badge
    Boffin

    Jumping bins...

    One point of matter- water does not compress. There's your upwards force. :)

    I recall participating in an amusing experiment involving muratic acid, aluminum foil, and a 2 liter bottle. the bang was pretty loud, and the cloud of aerosolized acid was amusing to boot. :D

  24. Winkypop Silver badge
    Mushroom

    When I were a lad...

    ..we made the explosions, the teachers tried to prevent.

    How times change.

    1. Francis Boyle Silver badge

      Re: When I were a lad...

      You obviously went to the wrong school. . .

  25. Zebo-the-Fat
    Thumb Up

    We need more like this!

    We need more teachers like this, my old physics teacher was a total nutter... lots of bangs and fun stuff... ruined my life and turned me into a total geek.... thanks!!

  26. Rob Wonka

    There will be a quiz tomorrow...

    Some questions to think about:

    Prior to the experiment:

    1. What is the expected distribution of balls after the event has concluded?

    2. Which conservation laws to you expect to be relevant to the outcome?

    a. Momentum

    b. Energy

    c. Entropy

    d. GDP

    e. Other

    Explain your answer.

    After the experiment:

    3. If each of the balls had the name of a different observer written upon it, and afterward they were randomly distributed among the observers, what is the expected number of balls to be matched with their mate?

    4. Describe the observed motion of the trash can and attempt to explain it in terms of the forces applied to it during the experiment.

    5. How can the total energy release during the experiment be estimated by the distribution of balls once stability was achieved?

    6. How might the end result have differed had the lid be place loosely upon the trash can?

    7. List 4 ways energy was released and distributed from the hot water to the other physical components of the experiment.

  27. cjrcl
    Meh

    Nice But It Cost

    This type of experiments is entertaining and conducive to science education whereas it may entails considerable environment deterioration or resouce dissipation. Hope people will correlate a experiment with some certain more tangible objectives other than pure entertainment or reduce its scale.

    1. Triggerfish

      Re: Nice But It Cost

      I don't think it would have cost that much to do, and if getting a bunch of people interested in science, or engaged with the subject they are being taught (because as this thread proves there's plenty of physics and chemistry to debate about around this demo) to an overall improvement is the end result then its money well spent.

    2. Michael Dunn
      Meh

      Re: There will be a quiz tomorrow...

      GDP? I fail to see how one instance of this experiment would affect the country's Gross Domestic Product - unless you are counting the number of foreign students attacted to study in British Universities as a profit to the country. In my experience, many of the best of them go back to where they live and set up rival industries to ours.

      1. John Hughes
        FAIL

        Re: There will be a quiz tomorrow...

        Wooosh.

    3. Trygve

      Re: Nice But It Cost

      "considerable environment deterioration or resouce dissipation" - are you kidding? Celluloid ping-pong balls and a few hundred millilitres of liquid condensed out of the air? Wouldn't surprise me if the balls were salvage from the sports centre, and liquid N2 is pennies per litre if you buy in significant quantities. The total environmental impact is probably equivalent to a couple of Big Mac Meals.

      I remember going to an evening event that revolved around a big flask of liquid nitrogent - think it was organised by the local science teachers or something. A hundred or so pimply of us tweenagers fascinated for several hours by a beardy loon doing all the usual cryogenic tricks including turning whisky into syrup. I think it cost us about 50p each for use the school minibus to get us there.

      1. cjrcl

        Re: Nice But It Cost

        The subject involved is not this case in particular. Some instances of this type of experiments may be less controversial. Pay attention to the number of 56649 in the following sentence excerpted from the penultimate paragraph of the article. "He has also roasted jelly babies in the name of science, and set the world's record for near-simultaneous fireworks-rocket launches: 56,649."

        Meanwhile, recycling those ping-pong balls should be time-demanding.

    4. No, I will not fix your computer
      Facepalm

      Re: Nice But It Cost

      Sounds like a terrible waste of resources, if only they had thought of videoing it so that it would be watched by millions, over and over again.

      Oh.... wait....

  28. zen1

    I think we could take him...

    While I'd suggest warm water and a couple of oz of dry ice, combined in a 2 liter bottle, I'm somewhat partial home made black powder. However, if you wanted to get a little exotic, either some pure potassium or sodium, throw it into a bucket of water. Comedy gold.

  29. JimC Silver badge

    Not a patch

    Pretty good, but not a patch on Professor laithwaite and his gyroscopes...

  30. Cupboard
    Mushroom

    you get a similar effect with dry ice

    It's great fun :) pop some crushed ice in a bottle, shove the bottle in a tub of water and kaboom!

    Whilst at university, I came across liquid nitrogen once. A lecturer had only managed to cover about 2/3rds of the course he'd set, and rather than try and cover some of it in the last lecture of term he brought in a tin of nitrogen and froze a couple of bananas. I wasn't convinced that it was an entirely good use of time or money and it wasn't even that fun.

  31. William Higinbotham
    Pirate

    Liquid Nitrogen Safety

    This is a great way of showing the dangers of handling liquid nitrogen. I know a story where a home thermos was used for holding liquid nitrogen (never use a non-approved container). Even the persons knew how to handle this gas, the lid was accidentally closed tight enough to cause pressure buildup. Extremely lucky enough, for the individual, he suffered injury which was not permenent. It could have been much worse.

    1. John Hughes
      Mushroom

      Re: Liquid Nitrogen Safety

      There was a story at Hull Uni about a large dewar of liquid nitrogen that was left in a lab - one day someone noticed that the neck had frosted over. Panic ensued, the dewar was carefully dragged out onto a sports field and the TA took shots at it. in an attempt to reduce the pressure.

      Turned out to be emptty.

      (Story probably bollocks).

      1. akicif
        Boffin

        Re: Liquid Nitrogen Safety

        Probably - you *never* plug the top of a liquid nitrogen dewar. On the other hand, if you have liquid nitrogen standing around for long enough for it to turn blue, then you need to dispose of it ASAACAP: (clue, it's how Salthouse makes his liquid oxygen)....

        (definitely safety glasses for this one!)

  32. John 62
    Trollface

    Units alert!

    or is it a units alert? I wasn't sure if liter was a miss-spelling of lighter.

    And if it was supposed to be litres, that's all very well for the masses who make do with those silly metric measures, what would be the equivalent in hogsheads? or olympic swimming pools?

  33. Crisp Silver badge
    Boffin

    Fuck I love Science!

    See Title :D

  34. Code Monkey
    Headmaster

    * litre

  35. FatGerman
    FAIL

    This video has been removed by the user

    BAh!

  36. James Pickett
    Unhappy

    "This video has been removed by the user"

    Just after I tweeted it, too!

    1. Akira25

      http://www.youtube.com/watch?v=8AUHnCthbY4

  37. Anonymous Coward
    Anonymous Coward

    Who removed the video?

    Damn - looks like I was too late. The video's been removed...

    :o(

  38. Stephen Hunt

    Re: removed

    Also here:

    http://www.youtube.com/watch?v=9RnkwXYmq-4

    3:30 for the impatient

  39. Imsimil Berati-Lahn
    Happy

    Hooray for Polytechnic Southwest!

    The old alma-mater.

    Last news I heard from those guys was the business school getting a media roasting for their degree course in perfumery which required completion of a smell test as an entry requirement.

    Good to see them getting better press for blowing stuff up.

    I wonder if they managed to sort out that concrete cancer on the Babbage building.

  40. Bucky 2
    Coat

    Just a TAD confused

    I understand the FIRST explosion, but not the subsequent ones.

    Also, where was Mr. Moose during all of this?

    You know...? Mr. Moose...? Ping-pong balls...?

    Crud.

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