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!

[FlaviaAlbia]

I did single science at school so I could do another language GCSE, plus I was told you absolutely had to dissect a rat and an eyeball for GCSE biology. Urgh, no chance, the thought still makes me queasy...

[VanillaSugar]

Don't call time on this thread . Thank you for your explanations. I will show this thread to my 11 year old DS as he will love it.


If you don't reply but keep lurking, thank you again and I hope you continue to inspire many young people. 🌟

[TimeIhadaNameChange]

Thank you, M3lon - that's really interesting. Will be interesting to see what he makes of it this evening!

[kateclarke]

I’m enjoying this thread too, don’t let people put you off.

[milliemolliemou]

OP, another thread on a different science point please. Perhaps MN could have a science section. Including experiments you can do at home with the kids ....... Another non-scientist here who would like to learn more!

[flowercrow]

OP I have no understanding of Science so don't find your explanations patronising at all, just don't understand most of this thread! I have a learning difference which makes me gifted in many areas and SEN in STEM subjects.
So please may I ask again, when you say you are trying to work out how to pitch information about the arrow of time, what does time have to do with how snow globes work? (For extra points, what is the arrow of time? Is it the artificial construct of time as linear?)

[ItsAllGoingToBeFine]

I'm enjoying the thread but some of it is a bit over my head. Personally I would rather be patronised so I can feel smug about how much I already know than feel stupid because I don't know/understand what are obviously believed to be very basic concepts.

On this thread, in the OPs posts, I'd have to Google entropy and terminal velocity. Some of the other stuff is a bit wordy, but I can puzzle my way through it.

I think it always best to assume the audience knows nothing, and to remember that basic scientific terms may mean nothing to a non-scientific person.

[ErrolTheDragon]

Millie - there already is a section https://www.mumsnet.com/Talk/scienceanddnatureclub but not many people know it's there. I guess 'club' may make it sound exclusive but every scientist I know is in favour of non scientists knowing as much science as possible!

[TeenTimesTwo]

OP. As a science minded (A level physics), but not over-knowledgeable person I think you have done quite a good job here and it has been interesting. But words like dissipating, and entropy tend not to be in every day use so need a non-scientific description quickly first before using them. e.g. For viscosity I use 'gloopiness'.

Surprisingly I don't recall ever having heard the expression 'arrow of time' or even 'flow of time' before. (And I'm kind of wondering why of all science concepts you want to discuss it, as for most intents and purposes it just 'is').

[ErrolTheDragon]

I thought 'the arrow of time' was quite a well known concept; there's a novel by Martin Amis called Times Arrow (which is about a man (un?)living his life in reverse.

The wiki is reasonably accessible I think https://en.m.wikipedia.org/wiki/Arrowoff_time

Want a science pun? Tough, you're getting one anyway...
'Time flies like an arrow. Fruit flies like a banana'

[TeenTimesTwo]

[flowercrow]

also I understand entropy to mean something like everything left to itself will revert to a state of chaos.
But I have absolutely NO IDEA what that means in terms of pragmatics.

[DadDadDad]

flowercrow - I think it's a statistical thing: disordered states are more common than ordered ones. (I won't use the word "chaotic" because that has a specialist meaning in science).

So, if we go back to the earlier example of a drop of dye in a beaker of water, each molecule of dye can randomly go anywhere in the beaker, so that means that it's quite likely that the molecules will be spread all over the beaker, but very unlikely that they will all be tightly together, so time's arrow takes us towards the likely scenario.

[Carboholic]

I am a scientist who occasionally does outreach and I have really enjoyed the thread. I spend A LOT OF TIME among patronizing people, and you are not one of them. Thank you!!

[ErrolTheDragon]

Statistical thermodynamics

[M3lon]

errol That was....TOTALLY uncalled for. I feel like my groan is still bouncing around the office...

[M3lon]

flower See if this is any good (feedback from you is welcome!)

If you have a tennis ball, and you hold it up and let go....it will bounce. If everything was perfect and no energy was lost to heat, or friction, or chaos in general, then the ball would continue to bounce exactly the same over and over for ever. If you were to video the ball bouncing...and then play it backwards...the two videos would be exactly the same. You would not be able to tell which one was going forward and which one backward.

One way to look at this is that when there is no movement of energy and everything is perfect, you can't tell time moving forward to time moving backward - because the forward and backward videos look exactly the same.

Now imagine a real life tennis ball. It doesn't bounce back up to the same height you dropped it from...it bounces lower and lower and lower. It is having is energy taken away and redistributed to the surroundings. Maybe a bit of the air is given some extra energy by the passage of the ball....maybe the ground is being slightly heated by the impact.

So when you video the real behaviour and then play the video backwards, you see two very different things. The mechanisms of heat/energy transfer have caused there to be a difference between time going forward and backward.

In general this is what happens. The movement of energy/heat from being in a single focused location, to distributed randomly about the surroundings is what happens when time flows in the direction we have chosen to call 'forwards'. Energy is not observed to go in the opposite direction. A ball lying on the floor doesn't suddenly collect a bit jolt of the energy in the surrounding and leap off the floor into the air.

The connection of all of this to the snow globe is essentially the same idea. The heat/energy transfer processes that occur when the glitter interacts with the liquid, the air, the globe, all conspire to produce obvious evidence of a direction of the flow of time. If those processes weren't present the glitter would bounce around indefinitely, never changing.

What I think is particularly interesting about all this, is exactly the question of whether this is fundamental. or an effect of human perception. The reason it looks to us as though energy is 'lost' from the bouncing ball or the glitter, is that we have a very biased perception of the world. We CARE about the tennis ball, we can see its behaviour. We can't see and don't observe the change in the air/earth caused by the energy of the ball being dissipated. So a god like being observing the whole ground/air/ball system, would see a set of states, all of equal energy, with different arrangements of the energy and, if also observing over all time, would see multiple times that the ball did get all the energy back and leap in the air....

So it does seem that it is our human perception that gives definition to the arrow of time, due to our short time scale observations, and our focus on the bigger human scale objects as opposed to the microscopic molecules and atoms.

[M3lon]

Well that killed the thread

[thricethebrindledcat]

All wrong, OP, they work by magic and the lady at Hamley's promised it's real snow in there.

[ErrolTheDragon]

Nah, everyone's been imagining the ball, heads going up and down like a nodding dog

[RealMaryMagdalene]

Hi M3lon!

Sorry taken me a while to get back!

I’m guessing from your explanations and mention of grad students that you have a background with physical sciences. If you aren’t from formal education and are just getting your knowledge without human guidance, just books or papers, seriously, look into getting yourself a degree! Your mind is incredibly smooth and at ease with these concepts.

So I was genuinely asking, what age kids?

As you know if you are a pro and trained which I think you are, physics is taught in layers. A professor of mine once told me that they found themselves having to wait for maths knowledge and experience to catch up. A student can understand the basic concepts of quantum mechanics long before (or if ever) they have the math skill to actually work with it or really absorb and understand the depths. Equally, we don’t skip introducing classic mechanics to preteens just because some will go on to develop this into a knowledge of quantum mechanics.

Special relativity in it’s own right is not passed by just because later things get a whole lot more interesting and accurate with general relativity! It’s a layering approach.

Time, well now there things get interesting and are continuing to get interesting! Did you see the results that came out of the LHC where a research group recorded paricles they sent out arriving at a later point in the physical destination tiny fractions of early in linear concept of time than the time they had been sent, not faster than speed of light. Bafflement all round!

We do now work, theoretically, with faster than speed of light concepts and there is a developing nature of the concept of time within applied and theoretical studies. So time is no longer, when looking at the maths which holds up, or the theories that are reasonable enough to be studied and investigated in applied science, limited at the previously held rules. Time is now considered fluid and incredibly complex in so many ways. Mostly based on theory, but that’s how science now works, a crazy genius had a theory, a few maths geniuses say «Hey, there is something in all this, it’s not wrong», then decades later applied research scientists get into proving physically.

Now, I’m not suggesting this is all appropriate or sensible for younger students, or students in process working through layers and needing decades to have even a chance at developing the math skills and mind if they happen to have the potential. My head just hit the desk because I’ve been through the maths on all these things, so I see more than a science fair kid. If a science fair kid did come up with the logic or math on time or any other of the currently being explored mysteries next in line to be really delved into, without training or experience, they would be a freaking genius, in the literal sense!

So my head hitting the desk is not a comment on inaccuracy, it’s my brain hurting because I sit at somewhere else in the journey, that’s all!

It’s not about me here however, or any non layperson adult as you made clear, it’s where kids are at in the process!

So it was a genuine question, that’s all, what age kids?

Incidentally I don’t think you are being patronizing at all. I think lay person explanations are really important! They work for the vast majority of young people and demonstrate to adults who may think they are not capable of understanding something that in fact, they absolutely are!

[RealMaryMagdalene]

Oh and how do snow globes work?

Magic, pure beautiful magic:)

[M3lon]

real thanks for getting back - I genuinely read your comment as indicating you thought I had the science wrong, but et pointed out the other explanation. I'm sorry I jumped to conclusions!

The answer to ages, is all ages, general public. This definitely makes it a challenge for the printed materials that stand alone. For talking to people at workshops its a bit easier to gauge as you are going along.

I will definitely try my explanations out on the kids I know. I asked DD (7 yo) how she thought snow globes worked and she seems really happy with arrow of time type ideas and was all over calculating for herself how different groups of outcomes (like total scores on multiple dice throws) have different likelihoods but maybe she isn't representative as she's also currently obsessed with fibonacci numbers and calculating the number of possible configurations of various collections of coloured lego bricks.

Do you have a link to the LHC thing you mentioned? The only thing I could find was the faster than light neutrinos which was an electronics issue in the end....

I've a colleague that manipulates light such that photons appear to leave before they arrived, but its all very much still within the bounds of relativity as normally expressed. Its more a technological trick that exploits the fact that photons aren't really anything like tennis balls, and can therefore do things that if you interpret them as tennis balls LOOK like them leaving before they arrived.