People don’t agree even how to measure how tall we are or how much we weight or anything. Probably not the answer you want but that’s probably why 😝

The units someone uses are ultimately going to depend on what they need them for. Someone working sending interplanetary radio signals might find light-minutes most useful, while someone studying orbits may likely use AU’s. If you’re trying to describe the size of orbits, using the orbit of Earth as a reference is really useful because it’s a distance that’s easy to compare to. It’s the same reason you don’t describe your weight in tones, differences of a few pounds are hard to conceptualize using units that are many times larger/smaller than what you can conceive.

Well what do you think "km" stands for?

> Light minutes, on the other hand, are a unit of time, not distance.

...what? no.

The AU and parsec, the two most commonly used astronomical distance measures, come from the fact that they depend on the most easily-measured things in the Universe: the parameters of Earth's orbit itself.

The AU is the distance from the Earth to the Sun. Geometry can easily tell us that, say, Venus is about two-thirds as far from the Sun as we are, or that Mars is about half again as far, but it can't actually tell us the Earth-Sun distance directly without some other pieces of information. Thus, a lot of the details of the solar system got worked out using the Earth-Sun distance (that is, 1 AU) as a baseline; as our estimates of the AU got better, so too did our estimates of other things.

Similarly, the parsec also depends on the Earth's orbit. In that sense, the AU and the parsec are closely related. Specifically, the parsec is the distance at which an object's position in the sky changes by 1 second of arc (1 / 3600 of a degree) over a distance of 1 AU. Mathematically, that means it's 1 AU times cotangent(1/3600 degree) = 1 AU times ~206,264, which works out to a little over 3 light-years. We use the parsec because measuring these angles is how we first established how far away the stars are, which let us develop systems for figuring out the distance to more distant stars.

Today, the parameters of the Earth's orbit are known to very high precision in terms of things like the kilometer, but that wasn't always true. And having probes far enough out to have meaningful light-travel delays is even newer.

Today, the AU is defined in terms of the meter, and the meter is defined in terms of light travel, so in a sense we actually do measure with light travel times. We just do it in a weird way for historical reasons.

Have you guys tried "kajillions of miles"

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>Light minutes, on the other hand, are a unit of time, not distance.

Light minutes are a unit of distance just like a light year is. In SI base units are speed is in m/s and time is in seconds so speed * time =m /s * s =m

A light second is exactly 17,987,547,480 m

That is because the speed of light is by definition 299,792,458 m/s so just multiply that by 60 seconds and you ger the distance above. If we improve measurement it is the meter that changes not the speed of light. A meter is the distance light travels in 1/299,792,458 of a second in a vacuum.

> Light minutes, on the other hand, are a unit of time, not distance. They are used to measure the time it takes for light to travel a certain distance. For example, it takes about 8 minutes for light to travel from the Sun to the Earth, so the distance from the Sun to the Earth is about 8 light minutes

You've contradicted yourself in this paragraph. Light minutes are not a measurement of time, they're a measurement of distance. You know this intuitively because you explained it correctly the final sentence here

Astronomers don't use light minutes within the solar system because they don't really care about light within the solar system, AU is just a more convenient unit.

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Astronomers do not always use light-years as a unit distance. The chosen unit heavily depends on the context. It could be light years (ly), astronomical unit (AU), parsecs (pc), kilometres (km), or others.

AU is convenient as it represents the distance between the earth and the sun. Using it for the distance between planets gives you a better representation than if it was given in light minutes.

In the same way that it’s more convenient to represent contenance in litres than in meters cubed

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Well, as a matter of fact, astronomers typically prefer the parsec over the light-year. A parsec is derived from the AU, is equal to 3.26 light-years, and is defined as the distance an object would have to be from the Sun to experience a parallax angle of 1 arcsecond (that's obviously not ELI5 but it's a digression).

The AU is better than the light-minute because the AU is a distance that we can easily understand. 3 AU is "three times the distance from the Earth to the Sun." I can wrap my head around that. What is 24 light-minutes? How far is a light-minute? You can tell me the equivalent in miles or kilometers, but the number is so big I can't conceive it as easily.

We can't easily conceive a light-year either, but when we get to distances larger than our solar system there isn't any easier measurement that we can grasp because it's way too far out of our range of human comprehension. The parsec doesn't help, and saying "thousands of AUs" doesn't help. We had to pick one, so we went with the measurement that sounds like it's a measurement of time and confuses everyone.

I’m not 100% sure what you’re asking but I’ll try.

If you are asking in gereral; Most babies can focus quite well (like the lens in a camera) on an object but they see it in low resolution. Like they’re recording in 144p instead of HD. Their brains aren’t well developed but the resolution improves as they develop.

They can measure this resolution in a variety of ways. One way is an optokenetic drum, once the baby is a few months old. The eyes will follow a stripey pattern travelling in one direction. If the baby can’t see or resolve the pattern their eyes will not follow it. You can adjust the pattern (bigger or smaller stripes) until the baby can/can’t follow it. With toddlers you can show them two cards, one with a faint picture and one without a picture. Watch where their eyes go and go to the next set of cards.

If you asking how we know a specific baby can’t see, we measure the focusing ability of the babies eye with a special light and lenses. And how well the baby can see with and without glasses with the methods above. If the baby falls significantly outside normal values, we give the glasses and/or eyepatches. If they are slightly outside normal values we might re-examine them in a few months.

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Your tl;dr is hilarious but true!

A network port is a "channel" for information received over the network. Your computer has physical ports, where a wire is plugged in (or a wireless connection by radio in many cases), but this port is not the same thing as a port being referenced by software. From the perspective of software a network port is the location of a stream of data made available to the software by the operating system. The operating system takes the data coming in to the physical port and divides it up into thousands of different virtual locations that can be used by all the different software running on the system.

Oh hey, I knew about the bad eye thing lol my right eye doesn't turn to the right. My peripheral is pretty strong but my body favors my left eye entirely

Doubtful you could get grant approval when there are cheaper, faster and more accurate methods of measurement available. Especially when it has been studied quite extensively already.

https://www.surveyophthalmol.com/article/S0039-6257(21)00134-X/fulltext

Lmk if I didn't understand your idea right, but based on my understanding of what you're proposing:

The issue with color matching is really the physical world. Mixing paints and printers aren't perfect but also leds and screen technologies are all a little different. Like one batch of leds may be a little more red, another a little more blue, so even if the computer gives the led the same color data, it will look different in the physical world.

But I think your idea could work, but you would need to control every stage of production and keep everything calibrated together:

• all designers computers in the same color space
• all monitors calibrated the same
• all printers calibrated the same (both in office and at in the print shop)
• and if you are using any digital displays, ideally those are all calibrated as well.

I think it's possible, it's just a lot of work for not much reward. And note that like anything in the physical world, it all deteriorates over time from wear or sunlight or whatever, so all those things would need to be calibrated regularly and done together.

Instead, we usually try and keep our pantone chips away from light, sometimes need to rebuy a pack, and just eyeball color matching with printers. It's generally assumed everyone in the chain has access to a well kept at least basic set of pantone chips.

Digital is a mess and basically we just don't have control (although I don't think ive ever used Pantone for anything digital). We test on as many different devices we can, but there's always going to be some folks with really terrible phone screens or something.

What happens when multiple services use the same port number?

>An MRI would never be used to measure focusing properties of the eye in a clinical setting.

Not clinically, no. But for research purposes a group could absolutely write a grant proposal to study development of the eye in early childhood.

That's not actually mote accurate, just more detail

An MRI would never be used to measure focusing properties of the eye in a clinical setting. It would be a very expensive, time consuming and “invasive” (probably not the right word) way to measure the length of the eye but I doubt it could measure the focusing power of the cornea or lens.

Autorefraction or retinoscopy would measure the focusing power of the whole eye. You can derive the power of the lens from biometry (measures the length of the eye and focusing power of the cornea).

Is it possible to get 12 color wheels of Pantone colors that mimic specifice color spaces, such as traditional RBY, RGB, CMKY and even artistically pleasant (but theoretically unsound) spectrums?

I would prefer wheels that have different saturation in rings. I have spent a lot of time fiddling with photoshopping and pdfs of a Pantone swatch book. It has been interesting, but I have to believe this work has been done before.