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Ask HN: What scientific phenomenon do you wish someone would explain better?

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Re: Ask HN: What scientific phenomenon do you wish someone would explain better?

#561

Post by maest »

arkanciscan wrote: post #173

Quantum Computers. Not like I'm five, but like I'm a software engineer who has a pretty decent understanding of how a classical turing machine works. I can't tell you how many times I've heard someone say "qubits are like bits except they don't have to be just 1 or 0" without providing any coherent explanation of how that's useful. I've also heard that they can try every possible solution to a problem. What I don't u…

IBM's Quantum Experience is great for this. It walks you through the quantum gates you can use and lets you write small programs for quantum processors.

I've found that to be the clearest way of understanding what qcs do.

Re: Ask HN: What scientific phenomenon do you wish someone would explain better?

#562

Post by air7 »

shadowprofile77 wrote: post #547

the fundamentals of computer science. Unlike many who comment here regularly, I am not a programmer or developer and though it might seem silly, the way in which a bunch of code written in a programming language of any sort translates to a computer physically or electrically causing things to "happen" because of it has always been a bit fuzzy. I know that electronic systems and machines translate all instructions to…

There's a great course called NAND to Tetris, which teaches, by example, at increasing levels of complexity starting from simple logic gates up to an actual program. It's very good. https://www.nand2tetris.org/

Re: Ask HN: What scientific phenomenon do you wish someone would explain better?

#564

Post by wsieroci »

I didn't see good explanation of Einstein's twin paradox. Have you seen one? I have seen only clear explanation based on fact that observer will feel acceleration when he will come back and this is what breaks symmetry, but it appears that explanation based on acceleration are wrong, because it seems that acceleration is not necessary to explain this paradox.

Re: Ask HN: What scientific phenomenon do you wish someone would explain better?

#565

Post by CJefferson »

Human Biology, particularly the "bigger scale" things like joints & ligaments.

I have arthrtic knees, and I'd like a better understanding of how joints work, and where the various clicks, pops and swellings come from.

It's easy to find really simple things, but harder to understand "how things go wrong".

Re: Ask HN: What scientific phenomenon do you wish someone would explain better?

#566

Post by kooshball »

badpun wrote: post #543
alasano wrote: post #380

Earlier quoted context omitted.

If you see a single share price listed, that is the price of the last sale that occurred. Now that can either mean that someone bought a share that someone else was selling or that someone was selling a share to someone who was offering to buy. The shares are listed as a series of buy and sell orders in what's called an order book. If the price a share was sold at was 100$ and you think it will go a bit lower, you co…

What happens if the stock sees almost no volume of trades, and we have a situation where the lowest sell is at $90 and highest buy at $100 (i.e. both parties are overgenerous)? Does the stock exchange make them split the difference, i.e. makes the trade at $95?

I assume you mean highest buy (bid) is $90 and lowest sell (ask) is $100. In this case there would be no trade. This is also called the spread.

If you actually meant your original wording, theoretically whichever order came second would fill at the best price.

Re: Ask HN: What scientific phenomenon do you wish someone would explain better?

#567

Post by drran »

sarthakjshetty wrote: post #558

What actually happens to the money that gets put into the stock market? I mean, I understand that there are people holding stocks and then people offer to buy/sell them at a given price; but, how does the company plan to benefit if the stock just keeps moving back and forth multiple third parties? Doesn't a company go public to raise money? If so, how does the company benefit from the daily changes in the stock and w…

Company raises money from market by giving away part of the company.

If company shares are cheaper than other source of money, then company can buy back them, or other potential owner can buy them. It also sends strong signal to owners and investors about future of the company.

If company shares are costing more than other sources of money, then company can sell more of them to return costly money back or to expand business.

For example, bank rent rate is 10% per year. Company worth is $1 million. Company created 1 million of shares. 1 share is $1 of company worth. Company pure profit is 10% per year. Company needs $1 million in circulation to operate.

If company will rent money from bank, it will have 10%-10%=0% of profit. If company will sell 100% of shares, it will have 10%-0%=10% of profit, but this profit will go to someone else. If company will sell 50% of shares and will rent $0.5 million from bank, it will have 10%-5%=5% of profit, 2.5% will go to company, 2.5% will go to other owners. By reinvesting this profit, company can reduce bank money or expand company to worth more, increasing company profit share.

Re: Ask HN: What scientific phenomenon do you wish someone would explain better?

#568

Post by gnu-nobody »

TJSomething wrote: post #539
skosch wrote: post #469

Earlier quoted context omitted.

Many problems require lots of huge matrix multiplications—think simulations of physical systems, i.e. weather systems or molecular interactions, or numerical optimization.

Additionally, many problems are can be converted to matrix operations, like graph algorithms. Note that matrix multiplication takes O(n^2) time with a quantum computer, but O(n^2.807) time on a classical computer.

> but O(n^2.807) time on a classical computer

Optimizing matrix multiplication for classical computers is an open research problem, and according to wikipedia there are algorithms with O(n^2.37) running time. Also according to wikipedia, it is not proven that matrix multiplication can't be done in O(n^2).

Re: Ask HN: What scientific phenomenon do you wish someone would explain better?

#569

Post by aeternum »

AlanSE wrote: post #402
SAI_Peregrinus wrote: post #334

Earlier quoted context omitted.

> while I get it that light is both a wave and a particle, but I have no clue what that means. Because it's wrong. It's a quantum of the electromagnetic field. It's neither a wave nor a particle. It just happens to have some properties of both.

I've done plenty of layman reading into QFT, and I'm truly good with this. All particles are really waves. There are no particles. There's self-interaction, and all other kinds of weird stuff. (it's important to qualify that stable orbits and molecules and stuff exist) But for the duality, there's something bigger that the responses always seem to blow past. Is wave-like nature for explaining behavior (wavy double-sl…

> If the photon refuses to choose just 1 slit to go through, why does it choose 1 spot on the photo paper to land on?

The photon (as a field excitation) goes through both slits, but is quantized so only has enough energy to trigger a mark at 1 spot on the photo paper.

> Why do we not still have to consider interference in outcomes after the photon makes its mark on the paper?

If we want to be completely accurate, we should. However so many interactions happen so quickly that the law of large numbers quickly takes over and obfuscates the quantum reality. Technical term for this is decoherence.

> Why are quantum computers hard?

Exactly because of this decoherence. It is very difficult to keep the qubit state isolated from the environment throughout the computation.

Re: Ask HN: What scientific phenomenon do you wish someone would explain better?

#570

Post by abiogenesis_123 »

javajosh wrote: post #527
abiogenesis_123 wrote: post #464

Abiogenesis. I understand that this is not considered understood but I'd be interested in hearing a qualified scientist talk about how we get from "dumb" matter to self-replicating, goal-driven matter. The closest I've ever heard anyone get (in a personal conversation) is that chemistry is about transformation, so "dumb" matter isn't really dumb in the sense that it's static. Still lots of hand waving to get from bak…

This question interests me as well, and I've done some thinking about it over the years. In particular, what I'm interested in is a hypothetically simplest object that can reproduce in a solution of simpler components, along with some differentiating characteristic. For example, maybe you have toroids that pick up particules, grow the torus until its too big, and then splits - and the ends of both halves click togeth…

> NB I'd expect none of these very simple machines to survive to present day - in fact, I'd imagine there to be several generations of early life, each obliterating/consuming/sublimating the ones before.

That's another really interesting axis of this topic -- why was early Earth special?

There may be no environments on Earth today that are like early Earth, but we could probably recreate them. Wouldn't we then be able to witness abiogenesis?

Or, early Earth wasn't special and abiogenesis happens today. If so, where do we look?

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