Liquid nitrogen flowers

7 03 2016

This is another look at a piece of internet science communication. In the first we looked at a section from Cosmos.

This is a small piece of The Science Museum’s Energy Show which has been officially posted onto YouTube by Focus magazine. Even though it depicts the performers without an audience it is fair to assume the directors and producers of the show were happy not only with this piece but with it being seen widely as an advertisement for their production.


Whilst it can be unfair to take a video out of context, often we miss important information either before or after the selection, this video seems to show an entire section of a rehearsed and scripted show so it is fair to assume this is how it is presented live. I think it is fair to critique what they have chosen to put on YouTube as an advertisement of their show. I have received replies from The SM before about comments I’ve made about their productions and I’d be happy to hear from them again about this and print any comments they’d like to make. I’m sure everyone reading this realises this piece is critique written with the hope that it informs everybody working in our industry. I write this with the best possible intentions and congratulate The SM on their ambition with the show.

If the link doesn’t work search ‘Science Museum Energy Show Dunking Flowers in Liquid Nitrogen’ and you should find it.

Even though this video shows only a small part of presumably a larger piece it demonstrates the dangers of introducing dramatics and characterisation into a science presentation. In this video the ‘business’, or the incidental activity performed by an actor for dramatic effect, doesn’t just fail to reinforce the science message it actually distracts and misrepresents it.

This is a shame because with a few adjustments they could have retained all the drama but used it to reinforce the essential science message.

There is a good reason dipping a bunch flowers into liquid nitrogen has become a science presentation standard. Flowers are a great way to show how fast something can be frozen in this incredibly cold liquid. That is the whole point of the demo. The flowers freeze extremely fast. This treatment of that demo has lost sight of this (if the writers were ever aware of it).

To comprehend what is going on the audience’s attention needs to be drawn to the state of the flowers BEFORE they are dipped. They are soft, they are flexible, the petals and leaves are firmly attached to the stems. Once the audience’s attention has been drawn to these characteristics then the AFTER, the disintegration of the flowers, vividly highlights that they have undergone a radical and fast change. The liquid nitrogen has frozen them.

Depending on the age and stage or your audience and the additional points you want to get across you can introduce other pieces of information. For example: flowers are made up of water that will freeze quickly at liquid nitrogen temperatures or flowers are made of cells that burst as the water inside them expands etc.

If we break their piece down:

8 secs: Why do they mention Halloween? If you wanted to draw attention to the fog it would be better to say: these are like the clouds your breath makes on a cold winter’s day. It performs the same job but accurately reflects what the audience can see AND what is actually happening, water droplets are being condensed out of relatively hotter air.

15 secs: Why enter into the fake dialogue? Is this from Star Wars? And what is it with that annoying noise the presenter makes? It took some digging around by this is the actual scene from The Empire Strikes Back this section seems to be referencing. (if the link doesn’t work search ‘Han Solo frozen in Carbonite’).

I’m sorry but for starters, and I hate to be the one to break it to you, Star Wars isn’t real…

Worse, Star Wars famously uses scientific terms incorrectly. Jedis use ‘the force’, Han Solo’s ship ‘made the Kessel run in less than 12 parsecs’ (a unit of distance not time), and ‘Carbonite’ is actually an early explosive not something cold. This is not me being grumpy, these inaccurate uses of real scientific terms are genuinely confusing for kids.

Using the example of Han Solo being frozen as being similar to freezing flowers in liquid nitrogen is like saying the way Superman flies is similar to the way planes fly. Yes there is a link, but making the comparison doesn’t reinforce any science message. Han Solo is brought back to life and apart from temporary sight loss is none the worse for his experience. The flowers get destroyed.

In the time it takes the performer to act out her dialogue and gurgle as she slowly drops the flowers into the liquid nitrogen she could easily have said: these soft and flexible flowers are mostly made up of water, I wonder what will happen to them and all that water when it goes into the incredibly cold liquid? She would also have had time to rub the flowers against her cheek to show they were soft and flexible, she could also have hit them off something or maybe dropped them to show that flowers that haven’t been frozen in liquid nitrogen are not going to disintegrate.

If you have to keep the Star Wars reference then work out a way that we know that the flowers are meant to be Han Solo. In the clip this is not clear at all. And if the point is that the actress thinks the flowers will be preserved intact and unharmed like Han Solo we need this pointed out as well. I think the Star Wars business here is not a help but a hindrance and I’d suggest it was got rid of.


26 secs: “Why are Anna’s flowers on fire?!” If the actress is trying to freeze the flowers like Han Solo was frozen why would she suddenly be afraid that the flowers were on fire? Why isn’t she aware that there is no fire here?

And from a science content point of view why would you want to make a link between the water vapour fog we see and smoke? Why would you want to introduce and reinforce one of the most common misconceptions audiences can have about liquid nitrogen? People are familiar with fire, heat and smoke. When they see clouds of fog coming out of a bucket of liquid nitrogen they often think they are seeing ‘smoke’ and assume if there’s smoke there must be fire. One of the most important things to get across when working with liquid nitrogen is that this fog isn’t smoke, there isn’t any fire, it isn’t hot. In fact, it is totally not hot, it is a substance colder than the surface of the planet Neptune!

What is actually happening is that the room temperature flowers are being dipped into a liquid that boils at -196 degrees Celsius. This is like dipping a piece of hot iron which has been heated up to +196 degrees Celsius into really cold water. The ‘hot’ flowers make the incredibly cold liquid boil. Although it might look like ‘smoke’ the clouds that we see are totally different. A good way to make this point is to get the audience to notice that the clouds are falling to the ground not rising up like we’d expect smoke to do.

35 secs: “It’s water vapour. The liquid nitrogen is so cold that it is causing the atmosphere around it to condense.”

This show is advertised as being aimed at English Key Stage 1 and 2, that basically covers primary school. In that one sentence the following concepts are mentioned:

water– are the children aware of water existing in three states? are they aware there is water in the air around us? do they understand that the clear colourless liquid in the bucket isn’t just hot water? Do they know that we call water when it is a gas…

water vapour- is the cloud actually water vapour? No, the clouds we can see are actually water droplets suspended in the air. It would be better described as fog which begins to form when water vapour condenses into tiny liquid water droplets in the air.

atmosphere– are the children aware of this term? Do they understand they are surrounded by air and that air is also inside the bucket?

condense– are the children aware of this term? Do they understand that things can exist in different states of matter? That water in one form can be turned into water in another form?

Finally, the sentence “[It] is so cold that it is causing the atmosphere around it to condense” is wrong. It is not the atmosphere that is condensing, it is the water in the atmosphere that is condensing.

If you have chosen to prioritise the drama and characterisation over science content and you plan to get the science out of the way with a single sentence then I’d hope that you could make a better job of it than this. The language used here is not suitable for the audience, the explanation given is incorrect, and most importantly the science spoken doesn’t actually reference what is most important part of this demonstration anyway- that the flowers have been frozen!

44 secs: “I thought they were toast”. Just when the script has tried to dispel us of the heat/fire/smoke misconception for the sake of a silly throw-away line the concept of heat/fire/smoke is reintroduced. This is is totally counter productive.

1 min: “I have cryogenically preserved your flowers in liquid nitrogen just like they did to Han Solo in The Empire Strikes Back“. What does croyogenically preserved mean? Is this something the children will be familiar with? And have you preserved them? We are about to see that you haven’t as they are going to get destroyed. Cryopreservation uses liquid nitrogen to flash freeze delicate biological tissues to avoid the freezing that destroys cells. As has been said already, the whole point of this demo is that the flowers are NOT preserved. The water in the cells is frozen and this is why they act so differently after they have been dipped in the cold liquid.

1 min 17: the flowers are destroyed by hitting them over someone’s head.

The video stops here. Perhaps the presenters go on to examine the pieces of flower that have fallen to the floor. Perhaps they go on to say- wow, that was unusual! why did that happen? and then do a series of other experiments to show why the flowers behaved so strangely after being dipped in the liquid nitrogen. Perhaps they found another bunch of flowers and repeated the demonstration drawing attention to the points I’ve made above. I haven’t seen the show so I don’t know.

What I would say is that even if all these points are addressed afterwards the writers have missed a trick here by setting up this piece in the way they have. And if they move onto something else entirely after the flowers are smashed on the actress’s head then it is a real shame because they have missed what I consider to be the most important part of a science presentation.

However theatrical you want to make a science-based presentation there has to be some genuine science content or you are mis-selling your product. All of the theatrics in your show should act to reinforce your key science messages certainly not distract or confuse the audience or worse mislead them. 





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