Physics Shoot ‘Em Up!

So it was all quiet in the Aspen Center for Physics offices.

Why? Tuesday family picnic outside…!

all quiet at the ACP?

Was it quiet out there? No! There were science experiments with the food of course!

diet coke erupting!

How did they get the diet cokes to erupt like that?

The instigator of this was Phenomenologist Josh Erlich, who is shown holding the secret ingredient… a common sweet/candy you can probably buy in the same place you got the diet coke…

josh erlich with secret ingredient

josh with mentos for diet coke experimentdiet coke erupting again!Know what the secret ingredient is? (I’ve blotted it out with green paint. [Update: I’ve added a new image (left) with the secret ingredient -mentos- revealed]) And do you know why it works? Tell us! (If you already know the answer -having heard it elsewhere- and don’t have to figure it out, then wait a while and let others guess or work it out.)


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53 Responses to Physics Shoot ‘Em Up!

  1. Stephen says:

    From what I hear, it works because the certain *ahem* candy has lots of nucleation sites for the CO2 in the soda to bubble up.

    On a side note, I just realized what an incestuous field Physics really is. Josh Erlich works just down the hall from me! I was talking about the soda trick just yesterday with Marc Sher, who suggested the demo to Josh. Small world!

  2. damtp_dweller says:

    Mentos and Diet Coke has been a popular diversion on YouTube for quite a while now. As Stephen said, my guess is that it’s essentially akin to introducing lots of nucleation sites into the liquid. That said, I have no idea why (or indeed if) Diet Coke should work so well in preference to other sodas.

  3. Stephen says:

    Anecdotal evidence suggests that other diet colas do not work as well. I saw one ‘experiment’ with tonic water, but the controls were faulty because they re-used mentos from a diet-coke fountain. It really says something about secondary science education, i think.

  4. Clifford says:

    Hi damtp_dweller,

    Very good; So you looked at YouTube and maybe saw the Today show, and maybe listened to all the NPR reports. The idea was to give readers here who did not already know about it a chance to figure it out, guess it, or go their own google searches. I certainly would never have guessed mentos could produce such a spectacular result!

    Anyway, as you suggest, it would be really nice to have a good explanation, or see a good set of experiments. As Stephen says, the “experiments” to be found on YouTube and Google Video, etc, are frustratingly unscientific.



  5. Clifford says:

    Josh said just now that he heard that in addition to the structural properties of the mentos already mentioned, there might also be help from the type of gum used to make the hard shell… it might reduce surface tension quite a bit. So the pitted surface encourages bubble nucleation and the reduced surface tension enhances the rate….?

    I’m still puzzled by the fact that it does not seem to work well with several other types of carbonated drink. I’ll put the conjecture out there that maybe different drinks have different characteristic bubble size, or some other natural length scale that is a function of the chemistry of that drink. Somehow diet coke is just perfect for mentos, whereas selzer water (say) is not. Would be nice to test…..

    Any other thoughts?


  6. Schwaumlaut says:

    Mythbusters ran a show on it today; using rock salt and valves (possibly in addition to gum arabic? THey didn’t say) they got 34 foot geysers. They also got the gum arabic to work in tonic water, so I think maybe whoever did the “other sodas don’t work” test got a bad bottle?

  7. Clifford says:

    Aha! Interesting new data…. Yes…. the gum arabic. Hmmmm.


  8. Stephen says:

    Salt, interesting. When I was an undergrad in dorms, we used to do “Sprite Bombs” in the dining halls. Basically you pour enough pepper on the top of a glass of sprite to cover the top (maybe 3-4 monolayers thick), and have a tablespoon of salt sitting on a napkin nearby. From the napkin you funnel all of the salt into the center of the soda. This is where it gets interesting: the pepper alters the surface tension and coats the outside of what is now a glob of salt as it sinks to the bottom. When it hits the bottom the pepper ‘container’ breaks, the salt contacts the soda, and it fizzes up, making a mess. A good time is had by all!
    IIRC, gum arabic is also an ingredient in Altoids. Anyone care to give that experiment a shot?

  9. Elliot says:

    O. K. its all becoming clear to me now. It’s the Mentopic Principle. Since pocket universes in the multiverse are a product of bubble nucleation, universes which generate more mentos have more offspring as a selection effect. We, (humanity) is simple an intermediate step to mento production. It is CNS + AP all in one nice package.

    The weak mentopic principle – We should not be surprised to find ourselves in a universe where mentos are produced because universes with mentos are overwhelmingly more likely than those without mentos.


  10. Clifford says:

    Hmmm…. Elliot, you might be on to something here! So do you think that in the less favoured universes, even if Mentos is created (by humans or whatever), they don’t have the dramatic bubble nucleation effects of Mentos universes? So they naturally fall off in population….etc.?


  11. Elliot says:


    Humanity is simply a catalyst for the bubble nucleation effects. Mentos by themselves fail.
    I need to dash off a paper right away before somebody “steals” the Mentopic principle and I am relegated to the dustbin of cosmological history. 😉

    I do need a bit of help on the SMP (strong mentopic principle) and perhaps the FMP (final mentopic principle)

    But right now I’m too busy calculating how many vacua are predicted by the mentopic principle.



  12. Claudine says:

    I’m not sure it’s as simple as surface tension. If that was the case, wouldn’t soap also work? Maybe salt and whatever is in the enamel of Mentos simply reduce the solubility of CO2 in water. It is known that CO2 is more soluble in fresh water than sea water. Also CO2 solubility would depend on the pH, which might account for the varying performances of different sodas.

  13. Claudine says:

    But I’m also taking this way too seriously. Please carry on developing the Mentopic principle of the bubble nucleation potential.

  14. Clifford says:


    Hi. It was not suggested that surface tension was the only effect. Instead, the it is structure of the surface of mentos that is conducive to bubble formation. The surface tension might just be a means of enhancing it further. Neither will do on its own.

    I cannot yet see how this all fits with the recent experimental data, or if a better model is needed…

    I’ll suspend disbelief on the Mentopic Principle approach yet. I’m not convinced that we cannot find a workable effective model of this which is predictive, even though the analysis may be difficult…. However, in case that is too simple, just plain wrong, some people might want to start investigating the different kinds of models that can in principle lead to an answer….. we might learn some useful facts about where to focus our search, by this sort of… how shall I put it?…. Surveying of The Landscape of possible models? (Hmm… Don’t know where those words came from, but they have a nice ring to them.)



  15. Clifford says:

    Oh… some people should be bold and try completely different approaches to the mint problem. It should not be all about mentos. Don’t forget the polo mint approach, for example. It’s been talked up a lot and so perhaps it is able to shed some light on this all.

    By the way, I don’t know if this is relevant or not, but remember the guy who used to go around saying that the polo mint approach to the problem was really just part of the same big picture as the mentos approach? I heard that now the press is beginning to turn against mentos (the approach is perceived as having got too big for its boots and the press prefer to sell an “underdog vs the establishment” story), he’s written books and articles saying that mentos have nothing to do with polos. In fact, they are supposedly now a central problem for mint physics in general. So I’m confused…..

    I suggest we proceed on all fronts…. Altoids anyone? Curiously strong mints you know. Might have a role to play


  16. Elliot says:

    But Clifford as we all know Mentos are the correct approach. Why would most of the research money be going into Mentos if they are wrong? I think a lot of the confusion is due to “some” people trying to hawk their anti-mentos books.

    BTW my early calculations put the number of possible Mento vacua at 10^158 (plus or mnus 3 or 4) that makes them 10^342 times easier to sort through than those other things people used to talk about.

    Next issues revole around what might be termed mint-symmetry. How many ways can they be arranged/degrees of freedom etc. I am confident that all other mint approaches will be subsumed into Mentos once the mathematics is right.

    Also thinking that we finally know what the “M” in M theory stands for if you get my drift (hint hint)

    Calculations were done years ago with Altoids and their curious strength led to them being un-renormalizable at the time.

    If other people want to go off and explore other Mint or Mint-like approaches, they can feel free. I’m staying focused and ignoring the naysayers.


  17. Clifford says:

    Hmmm, Elliot. Methinks we might have made this all a bit too obvious…. but what the heck… it’s fun!


  18. erc says:

    So the whoosh is just due to the already present CO2 escaping? I had presumed that there was actually a reaction going on that lead to the fountain effect, as when mixing sodium bicarbonate and vinegar (*so* much fun!), and so the acidity of coke was important. (I also assume coke is more acidic than other sodas as its base ingredient is phosphoric acid, but maybe this is another misconception?)

    Have fun doing the experiments!

  19. Elliot says:


    We now have a big problem. Previously the nucleation activity was theoretically assumed to be precisely balanced between expansion and recollapse. The latest data from measuring super-size drinks shows a clear and increasing expansion due to some un-explained phenomenon. Several people are calling it Mintervessence. But the majority of the cosmological community is calling it Dark Fizz.

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  21. watrbnder says:

    Everyone wonders what happens when you drop Mentos candies into soda. That is what I’m researching about. What happens? Why does it erupt? What’s the best kind of soda to use? What is the best Mentos to use? How far does the soda reach? Where is the best place to do the experiment? And who tried it first? I researched all those questions. First I tried to find what is in both and how it works. I researched that it and found out that scientists think it is a chemical in Mentos called Arabic gum. This is what one researcher wrote.

    “Mentos contains a chemical known as ARABIC GUM (this is the ingredient that makes the mint “chewy”). This ingredient causes the surface tension of the water molecules to break even more easily, releasing more carbon dioxide gas at an astounding rate! …..The gas causes pressure to rapidly build inside the bottle which thrusts the soda upwards in a wonderful fountain-like BLAST!”

    I thought that was very interesting. I also thought it was the Arabic gum but then wandered oft to thinking that it was the carbon dioxide in the soda. I researched it and I was wrong. It was mostly the Arabic gum and the carbon dioxide. Both have to do with the explosion. They also both effect how it erupts. “The Mentos effect has nothing to do with the inside of the Mentos and everything to do with the outside.” Steve Spangler says. So it is the Arabic gum that makes the soda erupt. But how does it really? Is it a chemical reaction or physical reaction? I looked it up on the web and I saw one theory of that. It said it wasn’t chemical at all. Its physical reaction. I was confused because I really thought it was chemical reaction because like the researcher said it when the Arabic gum causes the surface tension of the water molecules to break easily, releasing more carbon dioxide at an outstanding rate.

    To me that sounds like chemical reaction. Then after I found out how the Mentos cause the soda to erupt I had to find out which soda erupts the most and farthest for this experiment. I researched through the net and found out that diet colas are the best to use. But I wanted a specific soda that works best. I searched even harder and I had two choices. Either Diet Coke or Diet Pepsi. I chose Diet Coke because every other website was certain that, that soda worked best. Then I looked for the Mentos that worked best. I researched it on the computer and got mint Mentos as the answer. I also thought it was mint. Then I tried to find out where is the best and safest place to do the experiment. I researched and it said that the best place is to do it in an empty parking lot or a sink. Another place is on top of a pan. Just make sure its not somewhere where it spills. I collected this data not to do it yet. Just to research and find out.

    Next I looked up how far the soda might go when it flies up in the air. Some people reported about 10feet. That’s probably the average. I wanted to know who got the farthest. I researched over and over. I even looked in a book. Nothing. I guess people don’t know, since so many people try it. I looked to see who has tried it and what happened. How high it went and was it messy? I searched the web and found a site that said this kid tried it. It did shoot up in the air. It looked like about 5feet. He said it went all over his parking lot. So it was messy. Uh oh. I found this other person’s page and he also tried it. Same thing happened except that the soda went higher. He added more Mentos and more soda. He also used mint Mentos which is the best to use and Diet Coke. The other person used mint Mentos also but had normal Coke.

    Then I wondered who first thought of it. I looked it up on the web. It didn’t give me an exact answer. I finally found a page where it says that the famous Steve Spangler did the experiment first. I don’t think that’s totally true. Someone must have tried it before him. I went to his web just for kicks and found an article on the experiment. He also believed it is the Arabic gum that made the reaction. I looked to see who got the farthest again since I had nothing to do and I finally stumbled across a web where it says that the highest distance it has shot up is thirty four feet. I thought that was very cool. I then interviewed my cousin who says he has tried it and his calculations surprised me. His went ten feet! I thought that was amazing for a normal kid to do it and make it go pretty high. All he used was a two liter bottle of Diet Coke with 14 Mentos. He said “I didn’t expect it to go that high! It got my mom’s car wet!” Good thing he didn’t do it indoors.

    I can’t wait until I get to do it! I researched more about the topic and found some interesting things. The Mythbusters have also done this case. So I went to their website to find more information.

  22. Clifford says:

    Good Luck!! Come and tell us the results… !!


  23. ward says:

    this fucken awsome

  24. Tina says:

    So, did you decide if it is a chemical or physical change? I was explaining it to my kids as a physical change bk of the co2 coming out of suspension. But… I started to doubt myself.

  25. Clifford says:

    It sounds mostly physical to me… but I’ve not been keeping up on the latest experiments. See some oof the earlier comments above.



  26. ollie says:

    i think its mentos or polos cos i tries it

  27. Chris says:

    What r u guys talking about im 37 and i dont even know what ur saying so stp saying alll those cunfusing words!!

  28. Alex says:

    watrbnder, in case you are still asking about if steve spangler thought of it first, his website says: “My thanks to Lee Marek who originally shared the Mentos idea with me and to the hundreds of teachers and science enthusiasts who continue to share their funny pictures, videos and experiences.”

    Also, the number of mint mentos used on diet coke is still unclear. I used 7 on one of mine and it went about 1 and a half stories high. However, when I used 12 it had less impressive results. Another possibility could be the age of the diet coke.

  29. Rebekah says:

    I put this test into a science fair experiment to see if any other breath mints react with Diet Coke. Tic Tacs work almost as well as mentos. Ice breakers and Breathsavers were so- so. Altoids did nothing but bubble down the side of the bottle. After finishing I looked at the bottom of the bottles and all of them had the mints in the bottom except for the Altoids. So pretty much the altoids didn’t work. I weighed the mints on a triple beam scale so I would add the same weight to each bottle of Diet Coke. It was the only clear way I could keep the candies with a constant variable.
    Now, I’m trying to find out who the first person was to discover this worked. Does anyone know?

  30. Clifford says:


    I’ve wondered this too. I do not know. If you ever find out, come back and let us know.

    Good Luck!



  31. pokemon says:

    no offense i tried the trick and after the geyser happened i ate the mentos and the outer part of the mentos was soft

  32. chase and daniel says:

    we are doing this in science

  33. Clifford says:

    Good luck, chase and daniel!!!!


  34. Cristina says:

    That was so cool!!!

  35. spidysgIRL says:

    i found that the reactiion is a physical reaction not a chemical… and that the ingrediant that creates this is infact arabic gum it creates surface tension and then breaks up the molecules and makes the reaction happen and then the explosoin ignites!!1

  36. anoon kels says:

    i also found the same onfo as u. have fun with the expierments

  37. mingy says:

    im doing a experament on that im doing with me bro im doing it with 90 bottles and 63 boxes of mentos=)

  38. mingy says:

    lol lol lol lol lol lol lol lol lol loool

  39. mingy says:

    im doing a experament on that im doing with me bro im doing it with 90 bottles and 63 boxes of mentos=(

  40. mingy says:

    hello any1 clifford a least?

  41. mingy says:

    im doing a experament on that im doing with me bro im doing it with 90 bottles and 63 boxes of mentos:)

  42. Clifford says:

    Good Luck Mingy!!!


  43. mingy says:

    i got all messy but man that was fun!=)

  44. mingy says:

    does any1 go on this website anymore?

  45. mingy says:

    hello any one…………………………………………………………………………………………………………………………………………………………………………………………………………………………………echo echo

  46. Clifford says:

    Hello Mingy. I hope all is well with your experiments.


  47. mingy says:

    clifford 1 thing im done with it

  48. Clifford says:

    Ok. Hope you enjoyed it all. Goodbye.


  49. mingy says:

    are you leaving foreva?

  50. Clifford says:

    I’m not going anywhere…



  51. Rose says:

    I did this experiment at school. We used: original coke, original pepsi, rootbeer and sprite. And also mentos mints, polo mints and fizzy coca cola sweets. Other groups used a variation of mints. All the sweets worked in making the soft drinks fizz and “explode”. The mentos mints works better although polo mints works as good. The coke also fizzed up to a higher level. In the net, people claim that diet coke works better though. I was thinking, if theres a theory about how mentos can react with soft drinks, especially diet coke, are there theories on polo mints, lifesavers or other mints/sweets that are proven to react with soft drinks?