Liquid nitrogen + ping-pong balls = pure awesome

Dr. Roy Lowry demonstrates the awesome power of liquid nitrogen for a group of students at Plymouth University with a riveting demonstration that culminates in making an LN2-based bomb out of a water bottle, placing it in a giant rubber trash-can full of 1500 ping-pong balls, and waiting for the BANG.

Liquid Nitrogen and 1500 Ping Pong Balls Video (via Neatorama)


  1. Liquid nitrogen is always fun. Except when we use it in our radio astronomy work, in which case it’s just a tool.

    We even have tanks of helium and we never inhale it to talk in funny, high-pitched voices. Ever. Seriously.

  2. Yes, I agree. Anything that explodes or makes noise is awesome. I guess this is an example of what I would call the “Mythbusterization” of science. I really feel sorry for all of the science teachers of my past (in junior high, high school) – just think what those pre-technological science teaching hacks could have done with some ping pong balls and L-Nitrogen and a Fuji HD videocam.

    Who knows what kind of teacher this Dr. Roy Lowry really is (he sure knows how to create noises and explosions) but I certainly would like to see any YouTube videos of his that tackle larger issues (ie; sexually communicable diseases and/or the science behind global famine or even the horrors of global warming) Watching Dr. Lowry as he covers better or more lofty topics (in a gymnasium with ping pong balls, of course) would sure be a pleasure. Yes, students always love explosions and noises. Dr Lowry is the King of Awesome! Bang! Clunk!

    1.  The overriding problem with all of the issues you mention is poor education, specifically science education, and usually it’s the western policy makers that are poorly educated. Engaging with and inspiring enough people to learn about the world is how those problems are solved. All of your problems are eminently solvable with existing technology.

    1. Think of the trash can as more like a bubble than a solid object. When the bottle of nitrogen goes bang, expanding very suddenly, the trash can stretches in all directions (the expansion is too fast to push all the nitrogen gas out of the big hole in the top). The floor is a bit more solid and doesn’t move, so the trash can pushes itself up into the air.

  3. When a professor does this it gets posted on youtube and everyone loves it.  When I do it in my front yard the police show up…

    1. American high school (or college) science teachers are the new gonzo comedians, though this comedian (oops, I mean teacher) basically telegraphed his punchline by allowing his class to see the obvious bag full of ping pong balls and the always hilarious mysterious trash can. The reason I dislike stunts like this so much is that they make students look like morons (who’ll laugh at anything. Bang! Clunk!) – I’m sure this guy dresses himself up in a suit of Velcro and hurls himself at the Velcroed classroom wall in order to elucidate the principles of Motion and Stickiness. No wonder drop out levels are rising in the USA

      1. I had a chem teacher in high school who nonchalantly dropped a small piece of pure potassium into a big, open-topped jar of water, under the fume hood, shut the window of it and walked away.

        The class was pretty loud, and when the bang when off, it sounded like a stick of dynamite.  Everyone went silent.  And he said this is the SHIT you can do if you know chemistry.

        Nobody dropped out of his class.  We all passed.  Even the stupid kids.  Cuz they were willing to get help figuring out how to make destructive and poisonous shit.  The chem teacher never gave them enough info to actually make something dangerous, or maybe he did, but they never caused any problems in the school.

        Thanks to him, I was able to understand the distillation process, NMR, and numerous other physical and chemical phenomena I would probably hadn’t learned about without his enthusiasm for the subject, and his willingness to blow out our hearing at an early age.

      2.  You’re a bundle of laughs today.

        Kids like stuff that goes bang. Most adults do too. I do – that’s part of how I ended up with a PhD in physics, although I don’t get to make bangs very often now (and they’re usually expensive mistakes when I do!). This ‘stunt’ has two parts that I can immediately see as interesting. 1) It demonstrates the power in the expansion of a liquid-gas transition. 2) It illustrates an explosion in a fairly easy-to-see manner. Watch the trajectory of the ping pong balls. Also, as asked above, why does the bin leap in the air? Learning to observe what’s in front of you, and attempting to explain it, are both important skills for scientists.

        No, every science less shouldn’t be about explosions. But the odd dramatic show-piece is invaluable. Real working scientists love things that go bang and whoosh or turn pretty colours*. We could pretend that it’s all dry book-reading, and students mustn’t have any fun because science is serious stuff, but that wouldn’t be very honest now, would it?

        Oh, and wrong Plymouth, judging by the teachers accent.

        * This lot are, ahem, serious scientists:

        Lots of great videos here. I liked Chromium Trioxide:

      3. Yeah, he should stop doing all the stunts, so the kids can see what dull, pointy-headed nerds scientists REALLY are.  That’ll keep them interested in school. They’ll be lining up to follow in his footsteps.

      4. It’s obvious that you’ve been slighted by a large number of ping pong balls at some point in your life, and whatever it was they did to you has left you bitter and full of resentment towards ping bong balls.

        You have my sympathies.

      1.  I rather pictured him in a bowtie making a Dr. Who reference with a pun as an aside rather than a crappy pun – it makes it more enjoyable.

  4. To the naysayers:
    Chemistry teachers used to do this sort of stuff before the days of youtube. In fact, my chemistry teacher in the fifth grade (i.e. when I was 11, and that’s a few decades ago) showed us how different chemicals burn at different temperatures, we later made hydrogen through electrolysis (and set fire to the hydrogen, obviously) and other cool stuff. This is what has always gotten people interested in stuff: show what can be done with the knowledge. Show practical things, and show fun/impressive things.
    Chemists have ALWAYS made things go whoosh and boom, that’s just something fun within the field!

    Then we had the days of “ohmygoddddd…safetyyyyyy…. wear a helmet while walking, junior!” which went too far, and hopefully we’re coming back from that mentality. The Maker culture would certainly suggest that some people got fed up with that mentality!

  5. I’m still trying to work out what principle this demonstration illustrates. After all, these are undergraduates. They know from high school that the gas will have huge pressure.
    Maybe the principle is “Science is interesting”. But they’ve already chosen to study science, so I find it hard to see why he’s doing this.
    Except for fun.

    1. There was no announcement of the principle involved, so as a science lesson, it’s utterly lacking in substance.

      Perhaps there was a lecture in another room that covered the meaning behind the demo.

  6. I love how he handles the gloves at little bit while talking, but they are sitting on the table beside him when he’s actually doing the dangerous bits.

    1. Yeah, there’s a disturbing lack of regard for safety in this video. Seriously, handling liquid nitrogen without gloves and safety glasses is just irresponsible especially around students.

  7. Best science class I ever took was Conceptual Physics. No math, just had to be able explain the science — and demonstrations galore. The class was designed for non-science majors, but it was not easy. A couple times I went for extra instruction from TAs (who were studying for their doctorates, I believe) and got a kick out of watching them argue with each other about what the correct explanation was and struggling to prove themselves right without math. Some days it seemed they learned as much as we did.

  8. Great demo, but he really needs gloves and goggles on for the nitrogen handling, and ear defenders for when he seals the bottle, as does his assistant, you really don’t want to be close to one of those when it blows. It works just as well with dry ice in the bottle, but takes a little longer to blow, which builds up the suspense nicely and reduces the chance of the bottle exploding prematurely.

  9. Those ping pong balls make a wonderful noise as they land. Someone needs to make a conveyor of some sort that causes an endless cascade of ping pong balls on concrete.

  10. I love the slow drawn out  WWWWWWHHHHHHHOOOOOOOOOOOOOOAAAAAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH in the slow mo at the end. What would have been very intersting is if that class was combined with  some sort of strobe photography class as well.

    1. I remember when in my undergraduate physics lab, we students did the same thing.
      I also remember my dad bringing home a huge Dewar of liquid nitrogen and demonstrating its uses in the kitchen, one of which was to incidentally put out the pilot light on the gas stove. He did point out this effect and didn’t let the house blow up.

  11. Any other links for this same video?  I just got warning that it got yanked because the university is in a snit.

    1.  Just watched it on… I remember a physics lab where we all had a flask of liquid nitrogen, tall and open at the top for maximum spilling potential.  No recollection of the actual experiment performed, but do recall the good times finding items for freezie destruction.  The only day I wished I had worn a boutonniere to school.

    2.  I googled “Liquid Nitrogen Ping Pong Balls” and got a quite fun demonstration done on Ellen (with proper safety gear)

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