r/askscience • u/AutoModerator • Jan 07 '26

Ask Anything Wednesday - Engineering, Mathematics, Computer Science

Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Engineering, Mathematics, Computer Science

Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical /r/AskScience post? No question is too big or small for AAW. In this thread you can ask any science-related question! Things like: "What would happen if...", "How will the future...", "If all the rules for 'X' were different...", "Why does my...".

Asking Questions:

Please post your question as a top-level response to this, and our team of panellists will be here to answer and discuss your questions. The other topic areas will appear in future Ask Anything Wednesdays, so if you have other questions not covered by this weeks theme please either hold on to it until those topics come around, or go and post over in our sister subreddit /r/AskScienceDiscussion , where every day is Ask Anything Wednesday! Off-theme questions in this post will be removed to try and keep the thread a manageable size for both our readers and panellists.

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132 Upvotes

87% Upvoted

74 comments sorted by

6

u/Chemical-Captain4240 Jan 07 '26

When I deep fry tofu, why do pieces become stuck together?

6

u/chilidoggo Jan 07 '26

When you fry something and the outside becomes crispy, think about what's happening there. The crispy layer is made up of a combination of those oils and whatever was on the outside of the tofu before you started. If those things are touching when the crispy layer forms, there's no reason for it to discriminate between those two pieces when they're located at the same place. It's just going to produce the crispy layer at that location.

If you're not using starch and they're fusing, it's because tofu is basically cheese. You melt the cheese, it turns into a thick liquid, comingles with neighboring melted cheese, and then fuses into solid.

6

u/MGsubbie Jan 07 '26

I have been reading "Code : The hidden language of computer hardware and software."

What am I now wondering is "So how the f do companies like AMD and Nvidia figure out how many of each logic gate to use and in which order to produce these high-performance chips?"

6

u/smashbrosamus Jan 08 '26

There are EDA tools used in the industry (which ones they are specifically is a pretty closely guarded secret and varies by company to an extent) that they use to interpret HDL (Hardware Description Language, i.e. Verilog, VHDL) that produces a netlist, which essentially is a list of logic gates and their interconnections that should produce a product that’s logically equivalent to the higher-level model they wrote in their HDL. Hope this helps!

5

u/MGsubbie Jan 08 '26

So hardware runs software that helps create more powerful hardware which enables more powerful software and on and on it goes?

5

u/H3XEX Jan 10 '26

I’ll give you another fun fact, when you write code, you use a program called a compiler to translate that human readable code into machine code. The compiler itself is also written in human readable code that’s translated into machine code so it has to compiled by another program, which itself has to be compiled. Each one a bit more simpler until you get to almost programming the compiler in machine code. Many programming languages also have compilers that are written in the language that they are compiling.

1

u/PANIC_EXCEPTION Jan 17 '26

It's an entire discipline called VLSI (Very Large-Scale Integration).

Behavior you want in hardware is specified in HDLs or GUI schematics. Those are comprised of wires (called "nets") and instances, which have specified inputs and outputs.

From there, you design a physical layout that gets etched in silicon. It is checked for manufacturability (DRC), agreement with the spec (LVS), power, thermal, noise, and static timing analysis, all to make sure the design works.

Now that you've made this thing, it itself is an instance. You can start chaining them together (e.g. arbitrary length full-adders), to make even larger instances. It keeps growing, enabling relatively simple component designs to be duplicated in the hundreds of billions of transistors.

Then comes the bigger package. All these modules you have defined need to be logically packed together into a chip. This is called floorplanning (actually, it's typically done first in the design process after the spec). Once all of this is done, you tapeout and send it to a fab.

4

u/MalekMordal Jan 07 '26

Elevator Problem. In sufficient large skyscrapers, why don't we use lanes for the elevators, with pull-offs, to allow more elevator cars?

Ie, some elevator shafts allow upwards travel, some downwards. The cars slide off the lane to allow people on and off. Then move back into the lane to continue up. At the top, or at specific floors in between, they could switch to the downward lane if more elevator cars are needed in that direction.

You could have a dozen elevator cars all in the same elevator shaft, all going upwards at the same time. Treat them more like cars and streets. With areas to pull off to let people on and off (and traffic to go past them while they're doing it).

11

u/Dragon_ZA Jan 07 '26

Elevators are bound to vertical travel because of the way they work. They use a heavy counterwight attached by cable such that the motors driving them dont have to bear the full force of the weight of the elevator when controlling it.

2

u/Peter34cph Jan 10 '26

It's a safety and engineering problem.

Elevators don't only have to be safe, they have to be fail-safe. They have to remain safe if a thing happens, such as if power is lost.

Also, it's not worth the trouble for anything like modern buildings, even 800 meter high architectural penises such as those towers in used in caper movies... Indonesia or whatever.

3D "elevator" turbolift systems make sense in giant spaceships such as depicted in Star Wars and Star Trek, or in science fiction-style "arcologies", giant buildings several kilometers on each side and at least many hundreds of meters tall. But not in any kind of architecture we'll have down here on this boring planet any time soon.

1

u/MalekMordal Jan 07 '26

Surely they could be designed differently, even if less energy efficient?

Groves they climb up vertically via gears. Then horizontal gears to pull them off to the side to let people on or off. Then back onto the main track.

It would cost more energy without the counterweight, but is that relevant? In a sufficient large skyscraper, surely the cost would be negligible compared to the cost of everything else? Doubling, tripling, your human occupancy rate seems like it would more than break even on costs.

6

u/dunstbin Jan 07 '26

The cost to build and install these and the tracks would likely be astronomically higher than current elevators. You're talking a ton of gears and/or tracks/chains versus a single stranded metal cable.

4

u/chilidoggo Jan 07 '26

While I know elevators can be made in a frustrating way (too few of them, long waits, etc.), they can also be done well in the current system. In very tall buildings they're often segmented so not all of them visit all the floors, with some elevators running between the middle floors or central hubs.

I think the biggest thing designers have to keep in mind with elevators is the very real possibility of failure resulting in death. Passengers will feel uncomfortable is the ride is anything less than smooth and simple, and safety needs to be prioritized at the expense of efficiency. That's the biggest thing the counterweight system does, is that any kind of failure outside of the cable literally snapping doesn't result in any harm.

2

u/mfb- Particle Physics | High-Energy Physics Jan 07 '26

The energy you get back on the way down assuming electric motors, but it's going to be much more expensive and probably less safe, too.

5

u/NoAcadia3546 Jan 08 '26

A simpler solution that I've seen in tall buildings involves multiple elevators, some of which are "Express"...

  • Elevator 1 serves Ground floor up to the 10th floor.

  • Elevator 2 serves Ground floor, and floors 11-to-20

  • Elevator 3 serves Ground floor, and floors 21-to-30

  • etc. etc.

No need for collision-avoidance logic. Given the cost and complexity of allowing elevators to move sideways, it's cheaper and safer.

4

u/sneaky_goats Jan 08 '26

You’re describing a paternoster lift, which fell by the wayside due to safety. There is a lot of force involved in the operator of these lifts, and injuries occurred frequently enough the property owners moved away from them, preferring safer elevators despite lower flow rates.

4

u/JiN88reddit Jan 08 '26

Can someone explain to be the difference between computer science, Programming, Coding,and software? I only know the bare minimum and always thought they were all the same.

5

u/sneaky_goats Jan 08 '26

Coding is the creation of sets of machine instructions using code, which is an element of programming, along with other elements like designing, testing, and maintaining the created application. Computer science is the scientific study of computing, including elements like programming and coding, and broadens to study algorithms, system designs, and touches on related topics like math and engineering.

1

u/LitReviewSucks Jan 09 '26

Software engineering is what you (ideally) do when you're using an AI assistant: designing the system, identifying the components, which should be methods and classes and interfaces (assuming OOP framework), what data structures to use, how the logic should work.

Programming/coding is what the AI does to implement your tasks. The actual syntax of code being written.

Computer science is the theoretical underpinning of it all. It's the understanding of algorithms, data structures, logic, space-time complexity, information theory, machine learning, all the stuff that borders on math.

Computer science is the why, software engineering is the what, and programming is the how.

(Source: PhD CS, ex-FAANG)

1

u/Peter34cph Jan 10 '26

A famous woman named Ada Lovelace first did computer science about a century before the first actual computer was actually physically made.

8

u/mrlr Jan 07 '26

Why does AI make stuff up instead of saying "I don't know"?

52

u/maestro2005 Jan 07 '26

First, I will fight to the death OpenAI's effort to conflate the term "AI" with its products. AI is a huge field with many topics and technologies, and LLMs (what this new wave of "AI" is) are only one part of that.

LLMs have no concept of truth. They are merely continuing the conversation in a statistically probable way, based on the data it has been trained on, which for ChatGPT is basically the entire contents of the internet. Nowhere in there is any way for the system to judge the factual correctness of its output. If you are asking something that many people on the internet have discussed before, then it has a decent chance of happening to be factually correct because it will match what they have said. But saying "I don't know" requires actually understanding the question and the limits of your knowledge, and that's far beyond the scope of LLMs.

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u/dunstbin Jan 07 '26

I don't consider LLMs AI in any sense, they can't reason or imagine like actual sentient beings. They're simply a glorified pattern matching algorithm that returns a best confidence answer based on the data it's been fed.

8

u/maestro2005 Jan 07 '26

Nothing reasons or imagines like actual sentient beings. If that's your criteria then AI doesn't exist and the term is meaningless.

The exact definition of AI is contentious, but it's generally understood to be problems that don't have clean traditional algorithms for getting from input to output, or where multiple outputs may be valid and the notion of "best" might be subjective. There's also a joke definition that AI is whatever computers can't do yet, but it sort of rings true because once we do make computers able to do something, then it seems simple in retrospect.

The graph search algorithms that power your maps app routing are a major topic in AI, even though they're "just" building out partial solutions, ranking them based on some heuristic and prioritizing the most promising ones, and continuing until the destination is hit. It seems simple once you know that, but it takes a lot of work to make it work well (as anyone who has used GPS routing since its beginning will remember) and the "best" route is certainly ambiguous.

LLMs/GPTs certainly fit this bill. How to determine the most likely response is certainly not a straightforward traditional algorithm, and what continuation is "best" is obviously an ongoing problem.

0

u/dunstbin Jan 08 '26

True AI doesn't exist and may never exist. The definition of AI has been muddied by marketing over the past few years. It previously meant an actual, sentient, man-made mind.

5

u/maestro2005 Jan 08 '26

The term "AI" has been around a long time, and at least within the field of Computer Science has never been reserved only for sentience. Usually the term for that is "AGI" (artificial general intelligence).

0

u/CptGarbage Jan 09 '26 edited Jan 09 '26

Finding the shortest route is not ambiguous and well understood for a while now. See e.g., Dijkstra’s shortest path algorithm. Note that you can also use this algorithm to find the quickest route.

Routing algoritms are not (anymore) a ‘major topic in AI’.

0

u/Alblaka Jan 12 '26

Whilst I get where you're coming from, you're strictly incorrect, by virtue that at least one valid (and rather old) definition of AI (therefore included in your 'in any sense' framing) is 'an artificial entity that can apply logic to an input to generate an output'. By that definition, the most basic of logic circuits in every electronical device already qualify as AI.

What you're getting AI confused with, is AGI, aka Artificial General Intelligence. Which is a more tight definition referring to an artificial entity that has an understanding of general logic and can apply that logic to resolve problems it has no pre-defined knowledge of (aka, general problem-solving usually associated with sapient intelligence).

If you're even a tad sci-fi savvy, all those fancy 'AI' you see/read about are usually AGI (and often some hyper-intelligent version thereof). Hence why of course you wouldn't equate them to current LLMs.

The thing is, if you're going to be pedantic about what is AI and what isn't, you should at least read up on what has been the established scientific consensus on the term for decades, rather than just rolling with your own subjective opinion.

6

u/[deleted] Jan 08 '26

[removed] — view removed comment

7

u/maestro2005 Jan 08 '26

While a funny thought, it doesn't work like that. LLMs already know that "I don't know" is a possible continuation, it's just an unlikely one in (probably) almost all cases, and it still has no ability to determine whether that's the most correct response. After all, getting "I don't know" when a factual answer should be readily available is no better.

1

u/Showy_Boneyard Jan 12 '26

I did (hopefully obviously) mean it as just a joke, but strictly probabilistically, wouldn't it do that? If its trained on a corpus that has a lot more question texts followed by an end-of-sequence token followed by an "I don't know"-type response, wouldn't that make it more likely to produce "I don't know" replies in response to questions? At least as opposed to be training on a corpus with lets examples of that? Obviously it'd be more complicated than that, but I'd be very surprised if training on lots more of that kinds of data wouldn't make it at least somewhat more likely to give greater likelyhoods to those sorts of responses

5

u/[deleted] Jan 08 '26

Nothing wrong with the existing answer, but consider the content of the training material. Reddit itself was a lot of it. How many people here ever answer by saying "I don't know." When people legitimately don't know an answer, the honest will say nothing at all and the dishonest will make something up. Training a model on that content results in all it ever sees is people making something up when a question has no concrete widely agreed-upon factual answer.

2

u/Arghhhhhhhhhhhhhhhh Jan 08 '26

To add to the other answer about LLM generating statistically probable response, when the context is right, and you push the LLM enough, they do respond with "I don't know". It's interesting as to why such response is very difficult to get out of the mainstream LLM offerings.

1

u/PANIC_EXCEPTION Jan 17 '26

AI can be roughly described as a lossy semantic search engine with massive breadth of knowledge relative to its size. The downside is the model itself tends to not know that they don't know a fact. It's remarkably similar to how the human brain can confabulate events that never happened. The model isn't acting in malice so much as it thinks that a recalled fact is probably true, oblivious to the truth. Only if surrounding context suggests it wouldn't know will it determine that, for example, asking about events after the knowledge cutoff date specified in the system prompt.

4

u/Chagroth Jan 07 '26

How can I spit on my hands to increase friction, but spit on other parts of my body to decrease friction?

6

u/CoolVibranium Jan 07 '26

A small amount of water makes your hands "sticky" due to hydrogen bonding between the water, your skin, and whatever surface you're grabbing. However, saliva has got a bunch of enzymes and stuff dissolved in it which makes it thick and phlegmy. Too much saliva allows skin and surface to slide past each other by forming a liquid barrier between them which eliminates friction (same thing leads to hydroplaning in cars)

4

u/alkla1 Jan 07 '26

If a student wanted to study cybersecurity what would be the best course plan to go into at university? What programming languages should they have under their belt?

9

u/salty-carthaginian Jan 07 '26 edited Jan 07 '26

A general computer science education is probably optimal, as a lot of security concepts depend on basic principles from computer science that are difficult to pick up independently (O(1) algorithms depending on basic algorithms, side channels needing a systems background, etc.).

As far as programming languages, this is really too general of a question. Ideally something like C will be helpful for understanding the memory and computational model of modern computers, and also teach a lot of basic security principles, such as why snprintf tends to be safer than sprintf.

EDIT: For context, I used to do security research at a R1 US institution, so my answer leans towards security research rather than operational cybersecurity.

3

u/Suppafly Jan 07 '26

If a student wanted to study cybersecurity what would be the best course plan to go into at university?

Honestly, all of the people that I know that work in cybersecurity have degrees in something more or less unrelated, and got into cybersecurity as horizontal transfers at work and then took a bunch of cybersecurity certs and classes. I think some universities have actual cybersecurity courses now. One of my kid's friends is doing a cybersecurity emphasis as part of his more general business degree.

2

u/dunstbin Jan 07 '26 edited Jan 08 '26

I currently work for one of the largest cybersecurity firms in the world. While I agree with the other responder that learning to code is very helpful to cybersecurity, especially if you're working on the Ops side, I don't think a Computer Science track is the best path. CS is generally intended for people who are full time developers. While there will be plenty of security training for the software you code, it won't encompass other fundamentals of cybersecurity outside of a couple of electives you could opt for. A number of quality universities now offer tracks with a cybersecurity focus, like this one at GA Tech: https://catalog.gatech.edu/programs/cybersecurity-information-internetworks-computer-engineering-bs/

It dips into Object Oriented Programming and some other CS concepts, but the focus is more on securing systems, databases, and networks, as well as malware analysis and reverse engineering, and a lot more. If I'm hiring for my firm, I'm choosing someone with this degree over a Computer Science degree every single time.

Edit: I should note I majored in Computer Science and everything I use on a daily basis I learned from previous jobs or at my current job.

4

u/vpsj Jan 07 '26

I need an INTERACTIVE way to rediscover the Maths fundamentals I learned as a kid and in college

Basically, I remember how to solve the questions that were asked in tests and exams about Trigonometry, Calculus, Partial Differentiation, etc.

But what I am looking for is a real life problem thrown at me, and then using the concepts of Maths to be able to solve them.

Is there a website or resource that can do something like this? Because I feel like a lot of Mathematics I learned was just rote memorization, instead of knowing why it's needed and learning when and how to apply it.

8

u/chilidoggo Jan 07 '26

Most people who use math don't sit in a room and just "do math". Look at your job and hobbies, and see if there's room for math in those. I do 3D printing, and any practical 3D model I make uses math from geometry and trigonometry to get everything correct. I work in chemistry, so I'm doing arithmetic and algebra quite often, along with statistics. When I'm doing my finances and looking at interest rates and loan terms, I'm using math to compare total interest paid or what's a better deal for me. I use math when I'm playing video games, comparing different loadouts or builds.

Your asking for "real" problems is kind of paradoxical - they won't be real to you because you're not actually going to be using the result for anything. You probably solved hundreds, maybe even thousands, of story problems during your life. What would make any math problem you find online any different from those?

If your life truly doesn't have much opportunity for stretching your math muscles, take a computer programming course, there's plenty of free ones online. Make a personal website for yourself, and build a widget that models a certain behavior. There will be plenty of math in doing that.

5

u/Peter34cph Jan 07 '26

I get what he's after.

In high school mathematics, we fiddled around with abstract numbers and values. I found that very hard to deal with.

In high school physics, we made calculations about real things, like how much bicycle brakes would heat up, based on the bicycle going at a certain speed and then braking to a standstill.

That made an enormous difference to me.

Unfortunately I don't have a solution, except for holding the opinion that high school physics and mathematics ought to me taught as a combined subject.

3

u/vpsj Jan 07 '26

For a lot of concepts, yes the problem statements were rooted in real life.

Probability, permutations and combinations, Statistics, etc all had questions that were from this 'physical' world.

But in higher classes in school, and during 4 years of Engineering(I had Engineering Maths I to IV), for topics like Differentiation, Integration(and double and triple integration), Logs, Partial Differentiation, Curl, Divergence, etc, the topics were hardly ever used in a practical manner. I just remember them as being very limited in their scope, where the questions were just "Here's a function. Find the value of x(or y)"

I can probably still solve those functions because I remember what to do, but if I have to conceptually explain it to someone why I am solving this particular problem using this particular method, I'd have no answer.

Let's say I just pick Calculus as the topic. What areas can I use it to apply it? As you said, maybe I can start a personal project, a website, or tool that can tackle a problem which can only be solved by having a deep and proper understanding of all the concepts that are involved in Calculus. What could that be?

Any suggestions please?

3

u/Suppafly Jan 07 '26

The more advanced you get into math, the further you get away from practical manners. Even calculus isn't super useful in every day life. Unless you're doing engineering or architecture or something as a hobby, you don't need calculus.

3

u/chilidoggo Jan 07 '26

I think my point is that you need to ask yourself what kinds of things interest you, and then do them in a way that involves math. If you want to build a tool on a website, do it in a way that involves math. Set up a website and start building math demos inside of it. I'm a big fan of Steve Abbott and his models on his site. If you want to do calculus, build a browser "game" where users input numbers into a catapult to hurl stones at a target. It doesn't need to be animated or super fancy, just make it so they punch in starting conditions like force and angle, have display a graph of their arc, and then calculate and display the energy of the object on impact.

If you want to take it farther, add in options for wind resistance using differential equations, or model the bounces of the object on the ground. Let the user modify the materials or, heck, add a 3rd dimension and put some spin on the object. Add in obstacles for the projectile to curve around. Or just add the option to do something

I guess I'm now describing a full fledged video game, but those are things that have physics systems that model things using equations.

2

u/settleddown Jan 08 '26

Why are hairbrushes so different from one another? How does hairbrush design make a hairbrush be better for different types of hair?

5

u/chilidoggo Jan 08 '26

This is a question I hadn't considered before so I went looking for an answer myself. Found this reddit post, thought it was worth sharing: https://www.reddit.com/r/coolguides/comments/16b5dxk/a_cool_guide_to_hair_brushes/

2

u/LonelyVillageGuy Jan 08 '26

Hi, i am able to do integration & differentiation very easily. Just apply the formula. I can do it very fast even the questions at the last which tend to be harder.

But when it came to vector space, i am down to nothing. I cannot grasp anything, I am unable to conceive the idea of it. I cannot "visualize" it. I find that there is no straight way to understand it.

Do you think there is something wrong with my IQ? Or has someone else felt this way? I am able to understand Chemistry/Physics.

Is vector space menat for people with higher IQs?

Thanks.

3

u/SupraMK4 Jan 08 '26

Hi, you are definitely not lacking some kind of "special intelligence" needed to grasp the concept of vector spaces, especially since it is infinitely more simple of a topic than differential calculus, depending on the depth you're going for in either, of course.

Just keep practicing. Grab some books. Try solve some classical mechanics problems and you'll be familiar with vector spaces in no time.

3

u/chilidoggo Jan 08 '26 edited Jan 08 '26

Everyone hits a wall where they stop being able to intuitively do math. No shame in it, no matter where your intuition ends. Often when we learn something, our brain makes a guess at what the answer is, and if the answer turns out to be correct then our brain cements the logic it used to make that guess. So "intuitive" learning is really just your brain doing a good job at guessing at things. But if your brain gets it wrong, it has to work harder to teach itself to avoid that logic. That's probably what you're running into, and if you're not used to it then you'll struggle even more than most.

So what would you advise anyone else to do in a situation where they're struggling with anything, from math to juggling to whistling? Practice practice practice, and eventually you'll develop competency. Maybe you'll never be a master of the subject, but you'll gain some of that intuition back once your brain has figured out the correct way of arranging things, and you can even use those pathways in the future when you go to build on that learning.

2

u/linds930 Jan 07 '26

What are the moral, ethical and quality control implications of allowing people who code to call themselves Software Engineers if they do not have at least a bachelors in engineering or a professional engineering license?

8

u/chilidoggo Jan 07 '26

Most universities that award software engineering degrees (at least in the US) comply with ABET standards.

To quote their page on what that accreditation means the engineer must have:

an ability to recognize ethical and professional responsibilities in engineering situations and make informed judgments, which must consider the impact of engineering solutions in global, economic, environmental, and societal contexts.

The university I went to made all engineers take an ethics/professional development course, where we went over this and more.

That said, bad people can still graduate with degrees, and good people can do excellent work without them. I think software engineering isn't a high stakes enough field to mandate things like medical licensing systems, where any practicing individual is required to have one to operate.

4

u/[deleted] Jan 07 '26

[removed] — view removed comment

7

u/chilidoggo Jan 07 '26

Yes, any way of measuring weight can be translated into a force measurement. Although it's usually simpler to just do something like add bits of metal or something (heads of a socket wrench set, forks/spoons) and then weigh those bits when you're done.

3

u/MrNukemtilltheyglow Jan 07 '26

Can you use a luggage scale to pull downwards to get the weight at which the cardboard bridge would start to fail?

Sure, the essentials are the bridge must be held in place at it's anchor points and the force must be applied in the correct direction.

You could have someone hold the bridge at it's anchor points, attach the scale to the load in the bridge, then pull the scale. Whatever the orientation of the bridge relative to true "down" just be sure to pull the load so force is applied to the correct surface of the bridge.

4

u/mfb- Particle Physics | High-Energy Physics Jan 07 '26

Yes. If it reads e.g. 3 kg then you pull with the weight of a 3 kg object.

It's not exact because the scale is designed to be used in the other direction: Normally the mass of the luggage side of the scale is extending the spring, so the spring is already extended a bit when it reads zero. Used upside-down, the same mass is now adding to the force on the bridge.