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askscience

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la508 , in What shape would the universe's equivalent of a single pixel of 3D space be?

In 3D space it’s called a voxel

FlyingSquid , in Why does my arm hair know when to stop (re)growing but my "head" hair or beard don't know?
@FlyingSquid@lemmy.world avatar

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  • plumbus , in What shape would the universe's equivalent of a single pixel of 3D space be?

    I think the premise of a „pixel“ being the smallest entity in software is not right. Rasterization, i.e. translating (actually reducing) a defined subset of the software state into a 2D grid of colored pixels, is only a very limited view on that software.

    This might be the reason for the different answers we‘re getting here. Most aim for subatomic physics, it we could also go to light theory (photons and wave frequencies/resolution) and human retinas, general optics and electron microscopes, which again would end up at subatomic physics (you got my circle-train of thought here).

    quangdog , in What shape would the universe's equivalent of a single pixel of 3D space be?

    Hexagons are the bestagons.

    Ilikepornaddict , in Is it worth closing the lid on a toilet before flushing?

    I seem to recall that Mythbusters episode proving the exact opposite. They showed that fecal matter definitely gets sprayed all over the bathroom when the lid is up when flushed.

    slackassassin ,

    I watched that episode recently. They just proved that there are shit particles everywhere, and the expert agreed.

    Deebster OP ,
    @Deebster@lemmyrs.org avatar

    You may be right; it was about 20 years ago I watched it. Perhaps their conclusion was it happens just as much when the lid is down.

    stoicmaverick , in How does a signing a post with a pgp key prove that you are actually the person behind the post?

    I am probably at a similar experience level to OP and have wondered the following: is there a commonly used, or agreed upon repository for identity verification with PGP or similar? It would be a useful thing to use, the problem is that if you’re posting something to a public space, not everyone may have access to your public key for verification. Including the key in the message doesn’t seem like it would help much, since someone else could just generate two new keys and still claim to be you without any affiliation. Am I wrong about this? Thanks.

    perviouslyiner , (edited )

    Key signing parties used to be the thing to do at conferences - imagine a line of people, sheets of paper listing all their key fingerprints, and people showing ID to each other.

    PastaGorgonzola ,

    If this is some kind of messaging board, you’d probably put your public key in your profile (I assume that since OP is talking about the dark web that the posters there would rather not share their actual identity).

    Let’s talk about Alice, Bob and Eve. Alice is an active poster on a dark web forum. She puts her public key on her profile and uses the corresponding private key to sign her messages. If Eve wants to pretend to be Alice, Eve can simply put her own public key on her profile and sign messages with her own private key. But Bob is smart. Rather than just looking at the profile of the poster and copying their key every time, Bob saved it in his key store and assigned it to Alice (possibly even marked it as trusted). When Bob sees a post by Eve, he’ll try to validate it. This validation might succeed (if Bob has access to Eve’s public key), but it will be clear that the message wasn’t signed by Alice’s key.

    Of course, this all assumes that Bob has quite some knowledge of how this works and is vigilant enough to perform all these validations correctly.

    As for the regular internet, there are some services where you can share your public key: keys.openpgp.org is one of these. Of course, as /u/[email protected] says, there’s still the matter of trust. You need to make sure that the public key you’re using is actually from the right person.

    stoicmaverick ,

    That’s exactly my point. The gold standard would be a key signing party, but given that humans don’t tend to talk to each other in meat space much these days, it’s more of a rare occurrence than it used to be. I don’t really know what the ideal solution would be that would be a good mix of trust, privacy, and ease of use though.

    NielsBohron , in Is The Thought Emporium real?
    @NielsBohron@lemmy.world avatar

    Never heard of this channel, but either of those two claims would be a huge advancement in multiple fields, so the fact that it’s not being reported or published anywhere else is a pretty big indication that his claims are bunk.

    Like I said, I don’t know that for sure and I haven’t watched the videos, but I do keep current on most big advancements and I’ve heard nothing about either of these.

    6mementomori ,

    his claims aren’t advancements in any field, he’s just applying stuff we already knew before to a YouTube format

    DireLlama , in How young are the youngest fossils?

    The rule of thumb among paleontologists says that fossilization takes about 10.000 years, so that would be your youngest age. It should be noted, however, that there are many different mechanisms that lead to fossilization. The Lloyds Bank coprolite, for example, is generally described as a fossilized Viking poop despite being ‘only’ about 1200 years old.

    en.wikipedia.org/wiki/Fossil

    Candelestine , in If we have such a high field of vision, why can't we focus on everything within the vision simultaneously?

    A) Brain. You can train yourself to use more of your whole field, but you’ll lose that attentional “spotlight” that you normally aim at things and picks out all the detail.

    If you’re ever scanning something like a thick tree, looking for something, hold your arms out and form your fingers into a square frame. Use this to further focus your attention, and scan the tree in a more methodical way by moving the finger frame. You are more likely to find the thing you are looking for this way.

    ExchangeInteraction , in Does faster than light travel violate causality? Why/Why not? How?

    This argument, as far as I know, relies on the nature of time dilation. You see as your velocity increases closer and closer to the speed of light, time itself begins to slow down. This is not an analogy or some fancy math trick, this is a real thing you can measure in the lab. As you get closer and closer to the speed of light time slows more and more. Such that as you reach the speed of light (again this is physically impossible at least for anything with mass) you can think of time as stopping. So for light or anything that moves at the speed of light they’re kind of isn’t such a thing as time, but I digress.

    So (again even though it’s actually impossible), what happens as you start to go faster than light? Does this trend continue? If it does that would mean that time starts to reverse. And once you see that faster than light travel might imply time reversal, it should be easier to understand how this would violate causality. Because how do you get event A caused by event B when event B was before even A?

    surepancakes OP ,

    Thank you for your answer. When viewed from this perspective it makes more sense.

    WantsToPetYourKitty , in Does faster than light travel violate causality? Why/Why not? How?

    iirc the only method of faster than light travel that doesn’t violate laws of physics involves warping spacetime. We can now detect ripples in spacetime, and scientists postulate that in the far future it might be possible to manipulate spacetime by warping it with technology not currently in existence.

    Of course you could argue this method isn’t really faster than light travel, since you’re actually bending the distance between you and the destination.

    jasparagus , in How is the moon tidally locked?

    Here’s a good explainer:

    What is tidal locking? phys.org/news/2015-11-tidal.html

    Basically, the moon acted like a spinning (unbalanced) wheel, and eventually stopped with the “heavy” side pointing “down” towards Earth. I.e. think of the moon as orbiting Earth with the heavy side staying pointed at Earth.

    A_A OP , in is this the starting point of a new cosmology ?
    @A_A@lemmy.world avatar

    i only have access to the preprint :
    arxiv.org/pdf/2112.02444.pdf

    bstix , in Is the heat produced by fossil and nuclear fuel negligible?

    I’m not exactly sure of the context of the question.

    Electricity plants use the excess heat for district heating. It isn’t just wasted. If we could suddenly stop using coal or other combustibles for electricity production, we’d still need to produce energy for heating.

    Transport is different though. Gasoline engines are highly inefficient and produces a lot of excess heat that isn’t used even when the heater is on full blast. It’s not much in comparison to power production though, so while it will be more efficient to drive and heat a car by electricity, excess heat from cars isn’t really an issue in itself. It’s the pollution that is the main issue.

    Ephera OP ,

    Well, my thinking was that if the produced heat was not negligible, then it would be cooler (literally) to use energy for heating which is being pushed into our atmosphere already anyways, rather than actively unearthing additional energy.

    VirtualOdour , in If two identical radios are side by side and tuned to the same frequency, will they both pick up the signal at 100%, or will they wrestle for the same radio waves?

    People are answering what you asked but what you probably mean is in a 2d world where two antenna are perfectly in line with the transmitter will the first absorb some of the signal - yes it will, just like two wind turbines in a line it’s absorbing the energy from the medium and using it to do work.

    It’s not always so simple, it might spit some of if out too if it doesn’t have anywhere else for it to go and it’ll do this in a certain pattern which can, depending on the distance and arrangement ,increase the signal received by the second one. This and similar principles are why you see so many odd shapes for antenna designs such as the many bars on a TV antenna which make it more directional.

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