I’m not sure if I worded my question correctly, but let me try to explain more.
If we use a giant telescope to look at another planet 10 light years away from us, we would be looking at how it was 10 years ago. The thing I don’t understand is how does light store and also transfer all the information about that planet (or all the “data” that ends up in our eyes) and yet it’s still the fastest thing.
In: 94
The amount of information we receive *is* greatly diminished by light traveling such long distances. In fact, the amount of information we can receive is proportional to just how many photons we can actually catch. If we only catch a single photon we would only be able to determine information about that one “particle” of light – color for example.
When we make a bigger device, like a space telescope, it covers a really wide area and collects all of that light together to be able to glean additional information in an instant snapshot – “there’s a circular object”, detected by the difference in how much light was caught from different areas on the satellite’s mirrors; there was light in some places and not in others, and the border formed a circle.
Then we go one step further and compare that information over time to see more information: “this spot in the snapshot was light last snapshot and dark this one” or “that spot is brighter than this spot” gives us information about texture, or features, or speeds or movement, etc.
But to get “all of the information” from a planet, we would need to capture *all* of the light it emits, including the light coming off the far side of the planet. That would mean we need a mirror array that *completely encloses the planet*, and that’s unachievable even if we were really close by. Instead, the further you are and the smaller your apparatus, the less information you’re able to collect at a single time, and the more you have to make conclusions by comparing the image over time and noticing differences.
As for how light can transfer “a lot of data” and still be fast, it’s actually only able to transfer a lot of data *because* it’s fast – an individual photon can only transfer a miniscule amount of actual data, but we can observe trillions of them in rapid succession. Each “packet” of data is tiny, but because the transfer rate is so high we can collect a lot of information in short time by seeing the changes and variations in that tiny bit of data. This is the principle of fiber-optic cabling in computers: the information being sent over a single channel on the line is *only* a 1 or a 0 (on or off, lit or dark). But we can toggle that back and forth extremely rapidly, so in a short period of time we can capture billions of individual signals that are each individually extremely simple binary “on or off” messages, and translate that huge volume of tiny data into a large dataset / something useful.
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