This is something that has been bothering me for a while as I’m diving through space articles, documentaries etc. All seem to take our observations for granted, which are based on the data of the entire observable universe (light, waves, radiation…) we receive at our, in comparison, tiny speck. How do we know we are interpreting all this correctly with just the research we’ve done in our own solar system and we’re not completely wrong about everything outside of it?
This never seems to be addressed so maybe I’m having a fundamental flaw in my thought process.
How do you know the bird in the tree over there is real?
Well you can see it, photons have been emitted from the bird, which are captured by your eyes.
This is fundamentally identical to how we detect objects in deep space, we capture the photons, the neutrinos, the gamma rays, gravitational waves, whatever energetic emission is coming from them, and that’s how we know they exist.
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It’s the same way you know the things outside your window are real. You look at the light coming to you from that object and make inferences as best you can. As long as new observations and inferences line up with old observations and inferences, then you can be reasonably confident that your growing model of the outside world is accurate. When something doesn’t add up then you revise your model and keep iterating with new observations.
There’s no difference whether the object appears to be within our solar system or far outside it. We see something and we interpret what we can from the available observations. Occasionally, if something is close enough and interesting enough, we send a robot to orbit the thing or maybe land on it and gather better observations, like how Rosetta/Philae visited a passing comet.
In some fundamental way we don’t really know, all you can do is to make a model and then test it as extensively as we can. Then, try to break it and improve it, making it more precise, more general etc. However several things makes that guessing easier
One thing is cosmological principle, ie assumption that laws of physics are basically the same everywhere. One argument that makes this assuption hold better is Noether’s theorem https://en.m.wikipedia.org/wiki/Noether’s_theorem which means that at least some conservation laws are pretty fundamental. We don’t really know if laws of physics were the same in distant past, if they were then maybe there are some other, as of yet not discovered more fundamental laws of physics that hold in both conditions and simplify to what we know today in current conditions
The answer is predictability. We see things. We don’t know what they are or what they mean. We come up with theories about what they are and how they work. Those theories in turn let us make predictions about other things or behaviours we should see from similar things in the future.
If our predictions are correct, then we know our theories are good at describing what we see, and we thus have improved our understanding of how the universe works. Even if our predictions aren’t correct, we have learnt something.
Rinse and repeat over generations of scientists.
Observation is all we have. There’s no indication that anything outside the solar system is different from the things inside of it. Some stars have a light spectrum very similar to our sun, which implies they are stars in similar places in their life. Others have a light spectrum that is very different.
We can use different parallax angles to determine that some stars are much further away than others. Parallax works the same at 10 miles as it does at 10 light years.
Is there some particular observation you don’t understand?
Bruh. We can see it. We can also “see” wavelengths not visible to the human eye with radiotelescopes n shit.
You can see Andromeda, a whole-ass different galaxy, with your naked eye.
Voyager 1 has left the solar system and is in interstellar space, it hasn’t reported anything anomalous so far.
Whats different in our understanding within the solar system compared to outside? It’s telescopes looking at light from far away.
In ours we can send probes to confirm our observations, but the closest other star is so far away we’ll never even get 1% closer in our lifetime.
I’ve already gotten good answers to why this shouldn’t matter though.
There’s lots to learn about and lots of perspective shifts that (counterintuitively) can be found when you start to learn about particle physics.
I started to get into it about 2 years ago, and at first I was totally baffled. I kind of saw that as a fun thing though because it gave me cause to keep exploring backwards until I understood some fundamentals better.
Every time I started to think I grasped something, it just made more questions bubble up.
In the end, for as much as I think I understand about particle physics, I really don’t, but I sure as hell know about all kinds of scientific measurement processes, theories, and underlying concepts of how the universe works (which is fundamentally different than what we assume and what we have been taught).
You could make the same argument about our own solar system during the hundreds of years before space flight or probes existed. We knew the planets were there based on observation alone. There were many theories previously like the Heliocentric model that had our sun as the center of the universe but these were proven wrong without ever leaving the planet itself. The fact that probes now confirm that the other planets exists lends credence to the theory that other galaxies and solar systems exist too.
