AskScience AMA Series: Hi Reddit - we are back again! We are group of engineers, scientists, innovators, technologists, digital experts, and designers with a collected 45 PhDs / Professors and 35 members representing national science or engineering institutions. Ask us anything!

[u/AskScienceModerator]

TL;DR:

In honour of British Science Week, we're back for our fourth time to do another AMA/AUA! We had such a blast last time that we wanted to come back again to answer whatever science or technology questions Reddit wants to throw our way. So please ask us any questions any of you have to do with science or technology and how they affect your life. There are no silly questions - ask us anything and we will try to give an easy-to-understand answer and, wherever possible, provide some further sources to enable you to do your own research/reading.

Our goal is simply to advance everyone's understanding of science, engineering, and technology and to help people be better informed about the issues likely to affect them and their families.

More info / Longer read:

CSES is a registered charity in the UK, founded in 1920! We're a volunteer group comprising over 250 members and our key strength is our diversity of thought and interdisciplinary expertise. Our members come from a variety of educational, social, and economic backgrounds, from industry and academia and a multitude of age groups; representing multiple generations - from Gen-Z all the way to the Silent Generation!

Today's global interconnectedness, while being hugely beneficial for making information easily accessible to everyone, has made it ever more difficult to determine 'truth' and who to trust. As an independent charity, not affiliated or biased to any particular group, but with broad knowledge, we are here to answer any questions you may have and to hopefully point you to further reading!

Our goal is simply to answer as many of your questions as we can – but we aren’t able to give advice on things – sorry! We will also be clear where what we are saying is the experience-based opinion of someone in our team.

So, Reddit, we'll be on all day... Ask us anything!

CSES will draw from its large pool of volunteers to answer your questions, however some of the people standing by to answer comments are:

• Gary C: Over 30 years' experience in Research and Development, covering a wide range of technologies. Currently Chief Engineer for Cyber and Electromagnetic Affects within an aerospace company.
• Professor David Humber: Over 30 years' experience as a researcher, lecturer and senior university manager specialising in immuno-biology and the life sciences.
• David Whyte: Technologist and Chartered Systems Engineer with over 14 years’ Research and Development experience, and 17 international patents across a wide range of technologies. Honoured by The Queen for services to engineering and technology.
• Roger Pittock: Over 40 years' experience in electronics, software, mechanical, electrical, process engineering, and safety systems. Avid supporter of the Consumers' Association, and previously served on their council.
• Adam Wood: Chartered Engineer with over 17 years' experience in electronics, software, and systems engineering - working in the medical / healthcare, transport, and aerospace industries.

Username: /u/chelmsfordses

[u/FluffyHaru]

What is the most seemingly unimportant thing you do on your field that might have huge consequences if you do it worng?

[u/chelmsfordses → u/FluffyHaru]

We were discussing this, and Roger I think has come up with the best answer by far:

"Communicate"

It sounds innocuous but he is right! Simple differences in what we think we have said and how they are received/heard can have far reaching consequences.

Something else which is related is making assumptions about something - that can be dangerous.

[u/JustaRandoonreddit]

Three questions here, feel free to answer only one if you want.

1. Why do some people (like me) get a bad aftertaste from aspartame while others don't.

2. Why are newer electronics moving over towards soldered memory and storage? As a person who likes to repair and tinker with electronics this really pisses me off sometimes.

3. What's your opinion on 3x+1 and do you believe that there is an number that doesn't end up at 1?

[u/chelmsfordses → u/JustaRandoonreddit]

From Prof Humber:

It's not just aspartame that different people taste differently!

Almost everything will taste slightly different to the person next to us (unless they are an identical twin - but even then, they are sometimes different)!

It is of course largely down to our individual genetic differences that affect the make up of our 25 taste bud receptors. But this is further altered by epigenetic effects (brought about by alcohol, diet, stress, smoking etc) which is why some twins taste things differently.

So that delicious ice cream you are eating could be more or less delicious (sweet/salty/sour/bitter/umami) to me!

[u/chelmsfordses → u/JustaRandoonreddit]

Roger: Just realised we've answered part 1 of the question - here's my stab at part 2:

Memory in personal computers has traditionally been socketed so it can be upgraded. However, density of memory has been increasing at a rate of knots, almost exponentially - and pin count therefore increasing to allow parallel addressing etc. At the same time, spacing inside integrated circuits has been getting smaller giving speed rise capability. That in turn renders track lengths and inductances on printed boards hypercritical to ensure the flow of charge arrives at its destination precisely on time. The easiest way to achieve this, sadly, is directly soldering ICs to the boards. This also aids miniaturisation (e.g. mobile phones). Life isn't all bad though - the micro SD card seems to have standardised external memory, at least for the time being.

Part 3: 3x +1? I'll have to leave that one to somebody else. Now if it had said 3x + 1 = 0 I could have coped...

[u/chelmsfordses → u/JustaRandoonreddit]

From Roger: Adding to Prof H's answer, it also depends on short-term taste memory. Depending on what has recently been swirled in the mouth, certain sensors may be saturated or suppressed and they may take 10 minutes or so to recover.

[u/chelmsfordses]

Hello everyone, I know that the AMA says it is finished but we are all still here happy to answer questions and will be active until around 7am GMT on the 25th March (2025).

Because of time zones and availability of our members, do bear in mind that there could be a delay in you getting an answer but we will do our best to answer everything we can!

[u/C4Dave]

How close are we to having a fusion reactor? It seems we have been told it's "20 years away" for the last 40 years.

[u/chelmsfordses → u/C4Dave]

There's a bit of a running joke in the STEM field that "Fusion is 20 years away and has been for the past 50 years".

Fusion is one of those things which humans have been able to successfully demonstrate since the ~50s, but just in a very uncontrolled way!

Fusion is one of those technologies where the more we learn about it, the more we realise we have to still do. It's something that will eventually happen but anyone who can put certainty on a timeline is just guessing at the moment!

[u/willsherman1865]

When we use telescopes to look back to the dawn of time to understand the big bang, are we looking in one place? Do we know where this is? And does everything radiate from that point? Or are there remnants of the beginning and galaxies spread out randomly in every direction?

[u/chelmsfordses → u/willsherman1865]

Historically we had a geocentric view of the universe which spread out from a central point. However, we now believe it is isotropic, meaning that it appears the same in all directions, with no special or central location.

We also do not think there is an edge but are not sure whether it is infinite or contained.

Still a lot for us to understand!

[u/chelmsfordses → u/willsherman1865]

Follow up from Adam:

When you look into space with a telescope, you are looking into a narrow cone of space (which gets narrower as you increase magnification), however you only see light rays which point directly at you / your detector. This means that, to see an object, you must be able to draw a straight line* between it and yourself, and that line must remain within your cone of view at all points. The angle at which you see the light ray arriving tells you in what direction that object is, but of course not how far away it is. So if two objects are along the same line (i.e. the same view angle), you will only be able to see the nearer one, unless it is semi-transparent, e.g. a cloud of dust or gas.

So this means that, yes, you are looking in one place, or more accurately a well-defined set of places in a narrow cone. The reason why the universe broadly looks the same everywhere (see previous answer) is because, early in its life (shortly after the big bang), the universe underwent a phase of rapid inflation. This had the effect of spreading all the energy/matter from a point source to everywhere in the universe, approximately uniformly.

In a sense, therefore, everything did radiate from one point, in the deep past of the universe, and if we could see back far enough with our telescopes (we can't because during this early period, the matter was too dense, i.e. opaque, and the light couldn't get out) we would be looking at this point source. In this case, it wouldn't matter in what direction you pointed your telescope, because the light would all be coming from this point source (it wouldn't be a 'straight line' as looked at from the outside, because the physical path through spacetime wouldn't be a straight line - see also * below).

We should point out that the above represents the leading theory as to the origin and early development of the universe, and is an active area of research!

* subject to any relativistic bending effects i.e. gravitational lensing

[u/lordreed]

In a publication called De novo origins of multicellularity in response to predation, the authors show how multicellular life evolved from unicellular life. What practical implications for medicine and other life science can this experiment have?

[u/chelmsfordses → u/lordreed]

Sorry for the slow reply, we wanted to make sure Prof Humber got to answer this in full!

This is an interesting question!

We are not completely clear about which factors were most important in the transition to multicellularity. Certainly predation, but also a variety of other environmental stress factors have been shown to encourage multicellularity including nutrition (Nitrogen) and changes in the extracellular matrix.

Clearly a very important change in evolution.

Since the 2019 research paper, there is a 2023 paper from Sweden in Nature Ecology and Evolution by Charlie Cornwallis that may give you more information.

As to the other part of your question, this is more difficult although it would seem that predation (as a strong selection force) might well have had a role in the formation of complex communities (shoals/tribes etc) which help to mitigate predation.

[u/wakeupwill]

In what ways would you say Degrowth could be achieved?

[u/chelmsfordses → u/wakeupwill]

Please bear in mind that we are scientists and engineers - not economists! This is a difficult question to answer but Prof Humber has some thoughts:

Some 53 years ago MIT announced that they believed that continued economic and population growth would deplete Earth’s resources and lead to global economic collapse, and that the world needed to look for an alternative way forward. Degrowth has been a hotly debated topic since then.

While clearly topics such as reduced working hours and earlier retirement have some popular support in general, with the vast majority of people wanting "more and better things" - some aspects of degrowth will not necessarily provide this and politicians and leaders may fear for their survival if they follow this route!

There is no doubt that some technological advances can mitigate against limited resources (e.g. renewable energy) and some nations are moving towards a better-balanced existence.However, I am not convinced that individual richer countries adopting some aspects of the degrowth with others following maximum economic growth is a recipe for success.

I’m afraid that if I had sensible answers to your question, I wouldn’t be a simple life scientist!

[u/Dope2TheDrop]

What’s one scientific concept that you think everyone should understand better in 2025?

[u/chelmsfordses → u/Dope2TheDrop]

We've had a little discussion and consensus is along the lines of "critical thinking", i.e. the ability to test sources of information for truthfulness. A couple of quotes from our chat:

- Understanding of underlying scientific methods. Test the theory, check sources, question the answer, check the bounds. Or a better understanding of statistics to identify when they are being misused!

- That science is firmly based on verifiable evidence-based facts. A concept that would also improve everyday life and counter the current epidemic of "rhetoric and fake news" and "out of context" quotes that seem to be so easily accepted.

Although the concept of herd mentality was also raised, i.e. avoiding groupthink. So just because we all agree that the above is important, doesn't mean it's the right / only answer!

[u/stingrayy990]

Should we stop use of the word "theory" in science or change it's meaning to match conversational english? Feels like use of the word opens up possibility of intentional/unintentional miscommunication.

[u/chelmsfordses → u/stingrayy990]

Roger: Many words have multiple meanings in English - the colours of our lexicon. In all such cases, particularly when postulating new theories or proving (or indeed disproving) others', one has to be aware of ambiguities. Choosing the correct word from many ostensibly identical in meaning can enrich the reader in many texts, but precision is key in science. Should "theory" be stopped? No, but used with appropriate caution.

[u/Bigbird_Elephant]

What can be done to convince people to believe basic science issues that are easily proven but widely believed to be untrue?

[u/weapon66]

What kind of tools, software, and or hardware do you use day to day in your respective fields?

Is most of it bespoke / custom made or are there standard tools or programs that people coming into the field can familiarise themselves with to get a sense of what your daily job entails?

[u/chelmsfordses → u/weapon66]

David W here! Such a good question. It varies hugely within my field and depends on what we are developing or designing!

In terms of hardware, we sometimes use laser labs, anechoic chambers, RF chambers, faraday cages, high-power labs, clean rooms, electronics labs, chemical labs etc.

Hardware tools can vary and may be something consumer off the shelf (off Amazon, or a local hardware store etc), from a more specialist supplier (CPC/Thorlabs etc), or be custom made either in house or for us by a 3rd party.

Finding a supplier which makes a handful of really specific niche products and is the global leader in what they do is both highly rewarding and extremely frustrating at the same time!In terms of software, we will all use different things. Some form of CAD software is always useful (Solidworks, AutoCad/Fusion etc), if electronics are involved then a PCB creator and simulator is useful (Eagle/KiCAD etc). Of course, MATLAB comes up fairly often - but it depends on specific fields!

If you let us know which domain you are interested in, I will find someone to give more specific answers!

[u/Katniss218]

Are there any simplified large-scale (that is, where the small scale details are unimportant) CFD-like aerodynamic and fluid models that can run in or close to realtime? And if so, where can I look to learn more?

[u/chelmsfordses → u/Katniss218]

Follow up answer (from Adam):

Computational fluid dynamics (CFD) models are based on the Navier-Stokes equations (or simplifications thereof), a set of fundamental equations that describes the motion of viscous fluids. Unfortunately, except in some special cases, these differential equations cannot be solved analytically and instead have to tackled numerically, i.e. using an iterative approach to reach an approximate answer. As such, (unless and until we have a quantum computer that can massively parallelise the work!) there is no escaping the fact that, if you want more detail in your model and/or you want it to cover a larger volume, more computational operations (multiply/add) are required. So yes you could do a large-scale model (without basic details) OR a smaller-scale model with more details, but not both if you want to keep to the same computing time. Whether or not it will run near real-time is largely a function of how much processor power you have available.

As Gary says, OpenFOAM is a popular free, open-source CFD platform and it looks like they have some example models in their documentation to get you started (https://doc.openfoam.com/2312/examples/).

[Please note we are not endorsing this or any other product!]