to ask non-scientists how they think snow globes work....

[M3lon]

...and what would happen if there was no water or air in the globe with the glitter.

All for a good cause I promise!

I too have enjoyed this thread - thanks OP!

mrsP any particular slime? what do you mean by work?

If you are thinking like hagfish slime then the answer is long chain molecules and entropy again. In this case the molecules are much more complex and have exotic interactions with both themselves and more importantly with the water they are being pumped into. A small amount of these molecules can make a huge change in the local properties of the water. BUT all the bonds between the molecules and the molecules and the water are individually very weak. So it doesn't take too much time or slow pulling to disentangle them. This means they can appear claggy and almost solid like if you move them quickly, but can flow and eventually just wander off into the sea over longer time scales.

Slime is another non-Newtonian fluid....

imno cool! I guess its quite viscous if it traps bubbles, so I think you must be right, slow mixing is better. Sounds like they should come with a magnetic stirrer in them...

et I was only saying that to the person who clearly thinks what I'm explaining is wrong, or misleading in some way. I would imagine they have a very strong knowledge in the area to react against it that way. Maybe I misread it - but I was assuming there was expertise behind that comment.

Actually now I reread it - I see you may well be right! They might have been saying it was a mistake to use terms like thermodynamic driven processes if I was talking to kids!

I'm guessing you don't have kids M3lon? You've managed to avoid the slime obsession

DS particularly loved the lurid green stuff that came with plastic slime eels on a Cbebbies magazine. It got carried around everywhere until it became too revolting with fluff and soil and God knows what else...

ah....it is like silly putty? So stretchy, bouncy, but flowing also?

Man I am out of touch with culture!

In other news, I am thinking of getting my first smart phone but have absolutely no idea where to start. If anyone feels like helping me out...please do!

wait a minute, this isn't the same slime that's all over the BBC website for being toxic is it?

www.bbc.co.uk/news/uk-44852913

M3 - ahh, it’s late, easy to misread tone on the internet!

Science education is so important, it’s something I’m hugely passionate about and one of the things I really have to do is step back from my scientific vocabulary. It’s really hard because as scientists we’ve created these words that mean exactly what we want: entropy, non-Newtonian, thermodynamics etc , and other words don’t do as good a job - but if those we are trying to help learn don’t know what they mean then the more mainstream words Do do a better job. I usually focus on biology and the number of words I have to try to avoid is astonishing.

I know what a non Newtonian fluid is, but a sentence like the viscosity isn’t constant for different shear rates doesn’t make me feel empowered or like I have a fundamental understanding of a non-Newtonian fluid. And I’m someone with an extremely strong scientific background. When I read things like that I think it always makes it hit home how much complex language we use on a day to day basis: obviously I know what those words mean, and many people will be able to “translate “ into non scientific language, but that requires an extra layer of effort in a process many find difficult.

That's the stuff. It depends where you get it from, toy shops seem fine, but Amazon isn't as regulated.

Just tried the book again from the short end and caught it, but it only did half a turn. Any more than that and it spins.

What's the explanation for the book one? I asked DP who originally mentioned the pages being separate, but is now blaming human error. I need the answer to tell him in the morning when he's sober.

Sorry OP, I have to say that the explanation sounded a little patronising also. I'm only educated to GCSE science (many moons ago!) and only have a general interest in physics now... but even for me, the answer was obvious. I don't think you needed to invert commas around 'terminal' velocity... this is a very basic concept and I don't think you need to be a scientist to understand this! Just for me the 'terminal' sounded patronising, apologies if I read this wrong.

et sorry about that. I'll try again.

Think about a spring...if you pull it it stretches. If you pull harder it stretches more. For nicely behaved springs when you double your force of pulling it doubles the stretch of the spring.

The same things hold for fluids. If you push them, they flow. If you push twice as hard and they flow twice as fast, then we call them Newtonian. Some fluids resist less when you push them harder...so a small increase in pushing causes a big increase in flow rate. These are non-Newtonian and shear thinning. Paint and ketchup are good examples of these. Some fluids like oobleck become really solid when you push them so there flow can go to almost zero when you push, but will happen slowly under gravity if you leave them alone. This is also non-Newtonian but in the opposite direction, shear thickening.

Viscosity is the name given to the material property the decides how much flow you get for a certain amount of force. So water has quite a low viscosity, you get a lot of flow from a little driving force. Something like treacle has a much higher viscosity, you have to force it quite hard to get it to move at all.

Okay - I guess I should call time on this thread.

I'm finding it hard to decide where to pitch explanations given I've been accused of disempowering people by using the word viscosity and patronising people by indicating its possible they might not be familiar with terminal velocity.

It isn't rocket science to work out that people have different starting levels of understanding so the same explanation can easily be both disempowering and patronising.

I can just imagine some of you turning up to our event with your kids then complaining it went over their head while boring you.

I'm a PhD scientist and I was enjoying the thread! I think it's good you're canvassing non-scientists to work out how to pitch things.

time The book has three separate axis about which it can rotate. You can chuck it around from the two corner combinations previously discussed and also by holding it flat between your hands (as if about to open it) and spinning it that way. For the same amount of force spinning, the flat between your hands will spin the slowest (its inertia is highest for spins around that axis) and the other stable spin is the one that goes the fastest (its inertia is smallest for spins around that axis). The unstable one is in the middle (it has inertia about that axis that is intermediate to the other two). The biggest and smallest are stable processes like trying to balance a ball in the bottom of a curved bowl. You can get it a bit wrong and the system will correct by itself. The one in the middle is unstable, like trying to balance a ball on top of an upside down curved bowl. The slightest twitch in any direction and it will start to roll away. Its unstable because its in between the other two.

So really your husband is right. It IS user error, but unless he can perfectly control all the air currents in your house, he is going to have exactly the same problem...meanwhile even drunk he will be able to flip it in the other two orientations without any issues whatsoever.

errol well it seemed like a reasonable starting point...and I certainly learned a lot from the people who posted and I'm really very grateful for that!

It has all just made me rather nervous of putting myself out there.

I've got to write some stuff for a booklet and I'll definitely be testing it out on my non-science friends with their kids....

In other news, I am thinking of getting my first smart phone but have absolutely no idea where to start. If anyone feels like helping me out...please do!

I only recently got one... if you're likely to want to use it for anything where security matters (eg online banking) get an iPhone, apparently androids are much more likely to suffer from viruses/hacking.

It is hard to know what is 'common knowledge' and what isn't. For instance, I would guess everyone knows 'inertia' in the sense of 'a tendency to do nothing or to remain unchanged.' but I think 'moments of inertia' (as in your spinning book) is A level physics or mechanics. However, everyone must have seen a skater do that thing where they're spinning with a leg sticking out and then bring it in and suddenly go much faster... they know the effect even if they don't know the words or the maths.

I just read your definition of the science words. Personally I like teachers to treat me like I'm stupid so I learn rather than being left feeling more stupid (if that makes sense). My head hurts now though!

m3 I agree it’s a mare where to pitch - my comment wasn’t meant to be accusatory at all, I was just thinking through things - I do understand how non Newtonian fluids work and your explanation both pre and post removal of the word viscosity is of course totally correct, and I guess maybe I’ve had an unusual set of experiences with the level of scientific knowledge people have. Don’t feel you have to in any way call time because of me; I think it’s a great idea. I’m really sorry if I have made you feel like this is a difficult or non-worthwhile task - that really wasn’t what I intended.

I didn't think you sounded patronising at all - your posts are clear and interesting, OP.

I am a non scientist and love different ways to understand how things work.

I have found this thread hugely interesting and entertaining.

AutisticHedgehog: “as a PhD Student” is possibly a way to begin a sentence to turn non-scientists off . Go straight in with the question or material. Knowledge is knowledge: we all have the same right to understand it no matter who we are.

I’m enjoying the thread. No need to call time.

I was useless at science at school but have a DS who is fascinated

OP i love your posts. I'm learning so much from them and it makes me wish I hadn't been such a Wally at school about science

Really enjoyed reading the thread and all the explanations and activities. Thanks OP - I'm very aware that my science knowledge is limited and reading things like this helps me with doing stuff with DS