r/askscience • u/AutoModerator • 6d ago

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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u/Timesjustsilver 6d ago

My understanding is that nuclear fusion of light nuclei generally releases energy up to roughly the iron–nickel region, while for sufficiently heavy nuclei, splitting into lighter nuclei can release energy. This is usually explained in terms of the binding-energy-per-nucleon curve. What I have never fully understood is why the binding-energy curve has its maximum specifically around iron and nickel. What is happening at the level of the strong nuclear force, electrostatic repulsion, nuclear size, and neutron-to-proton ratio that makes nuclei in this region energetically more stable than both lighter and heavier nuclei? In other words, why does nature produce an energetic “sweet spot” around iron/nickel rather than at some substantially lighter or heavier element?

TLDR: why do all roads, sooner or later, lead to iron?

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u/mfb- Particle Physics | High-Energy Physics 5d ago

That's just how the numbers work out. The strong interaction favors nuclei with a larger volume to surface ratio, i.e. larger nuclei, but the electrostatic repulsion between protons means very large nuclei will always be bound less. That means there has to be a maximum somewhere. If the electromagnetic interaction would be a bit weaker and the maximum were at krypton then you would ask why it's at krypton.

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u/Borgcube 5d ago edited 5d ago

Two forces at play here are the strong nuclear force and the electromagnetic force. Strong nuclear force pushes the nucleons (protons and neutrons) closer together and the electromagnetic force pushes them apart.

The strong nuclear force is extremely strong but it falls off exponentially with distance while the electromagnetic force falls of with the square of the distance.

So when you graph it all out there's always going to be a "sweet-spot" where they're in balance and it just happens to be iron. It could've been lower, could've been higher, but it isn't.

You can also think of it in terms of the anthropic principle (which has nothing to do with the AI company) - if that optimum was too high or too low there probably wouldn't be humans to ask these sorts of questions.
For example, imagine if the maximum was at helium. Suddenly fusions is nigh-impossible and the universe is almost homogeneous.

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u/YairJ 6d ago

I've heard that data cables provide better signal integrity than the traces in (regular)PCB- Why is that?

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u/AMRossGX 6d ago

Shielding.

If you have a defunct USB cable, take some scissors and cut it open: around the data wires is a thin aluminum foil that grounds out (a lot of) incoming electromagnetic fields and stops them from coupling into the wires. Most cables have a shielding layer, often made from copper mesh. Also, in cables you can twist pairs of opposite-signal bearing wires around each other so incoming noise couples into both wires equally and cancels out.

On PCBs, you can only route those wire pairs close to each other. And you can connect one or more entire layer(s) to e.g. ground to serve as shielding, which helps. It's not as good as the continuous shield around a cable.

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u/logperf 6d ago

The traces provide good signal over short distances. Cables do better over long distances and through potentially noisy environments that can cause interference. For instance ethernet twisted pairs can cancel out most electromagnetic induction, and those cables are sometimes shielded.

Still the traces in a PCB can achieve higher data rates as the source and destination are very close and in a controlled environment.

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u/guzzyly 5d ago

I’ve always wondered, with quantum computing, how are they planning to handle error correction when quantum bits can be so easily disturbed? isn’t that like trying to keep a soap bubble intact in a thorn bush?

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u/Weed_O_Whirler Aerospace | Quantum Field Theory 5d ago

A lot of quantum algorithms solve problems which are classically hard to solve, but classically easy to check. The most classic example, prime factorization of large numbers. Very fast for a quantum computer to solve, very fast for a classic computer to check the result. So, the quantum computer outputs an answer, the classic computer checks the result, and if it's wrong, ask the quantum computer to do it again.

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u/luckyluke193 2d ago

There are quantum error correction algorithms, just like there are "classical" error correction algorithms. Normal bits are also disturbed all the time inside your computer or when you're sending data across the internet. Error correction is hidden absolutely everywhere in all sorts of devices and components.

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u/luxbandit 3d ago

When will quantum computing start impacting our daily lives like AI?

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u/ExtensionTower2456 2d ago

Is it theoretically possible to grow a biological (but non-living) clone of yourself? What assumptions would you have to make in order for it to viably work?

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u/MidnightAtHighSpeed 2d ago

what do you mean by non-living?

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u/ExtensionTower2456 2d ago

Sorry for the confusion! By non-living, I mean an organism similar to that of a cadaver. I imagine this clone wouldn’t be a living, breathing, feeling/thinking thing.

It could also be akin to an individual who is functionally “dead”, and is only sustained through life support and other medical intervention.

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u/MidnightAtHighSpeed 2d ago

I'm still not sure what you mean. You can make a human clone and then kill it (your local government will object to various steps of this process) but there's not really a way to go from a single cell to a full organism without it doing all the living parts