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I don’t really understand how we can make conclusions about the entire universe when literally all of the data is collecting from one point in space. Couldn’t t

I don’t really understand how we can make conclusions about the entire universe when literally all of the data is collecting from one point in space. Couldn’t there be local effects that obfuscate global behavior? Is there an implicit caveat asterisk on all such statements that is like “as far as we can possibly tell from the data we have” and the reality is we really, really don’t know for sure?

luc4sdreyer 3y ago
>from one point in space - We have multiple observatories on and around the planet - The Earth is moving around the Sun - The Sun is moving around the centre of the galaxy - The galaxy is moving towards the great attractor, etc The Copernican principle states that humans, on the Earth or in the Solar System, are not privileged observers of the universe, that observations from the Earth are representative of observations from the average position in the universe. This has been tested in various ways: https://en.wikipedia.org/wiki/Copernican_principle#Tests_of_the_principle https://en.wikipedia.org/wiki/Copernican_principle#Tests_of_... A nice PBS spacetime video about the topic: https://www.youtube.com/watch?v=q-6oU3jXAho https://www.youtube.com/watch?v=q-6oU3jXAho You can also ask how do we know that the laws of physics haven't changed over time. We don't. But at some point you have to make a few basic assumptions in order to have any hope of making scientific progress.
mr_mitm 3y ago
> “as far as we can possibly tell from the data we have” Isn't that self evident in all cases? In cosmology, the implicit assumptions are the Corpernican principle and that GR is correct. That is covered in introductory texts, but unless stated otherwise, it is usually not mentioned, especially not in press releases. I mean, maybe you're just a Boltzmann brain floating in space and nothing is real. Fun to think about, sure, but expecting to state the basics in any and all cases is unrealistic.
- pfannkuchen 3y ago
  I’m not talking about physics being different in different places. I’m talking about the signal we are getting from far away quite likely being altered between its origin and when it gets to us. Different branches of science have vastly different degrees of certainty. I don’t feel there is sufficient effort put towards communicating this well to the public, especially with respect to the Big Bang, and that annoys me because lay people seem to use it as a factual version of an origin myth when really it probably isn’t any more factual than any other random myth you could pick. It’s very irresponsible to replace the cultural origin myth, which is psychologically important to humans. The whole “explosion from nothing” myth may actually be contributing to modern people’s feelings of meaninglessness.
SkyBelow 3y ago
Yes, there is such an implicit caveat on all of science. Science at its core runs on a repeated process of collect some data, explain it, collect some more data, explain it as well, and keep repeating forever. The scientific model you are likely more familiar with refines this a bit where you use the current model and data to direct where you spend your time/funding collecting more data, but that is mostly a heuristic. Sometimes a person going off on their own will find something amazing to bring back, but we have to remember that many others spend their entire lives and end up finding nothing new or noteworthy. One problem with science literacy is that too many people treat the existing models as true, even when they aren't. In some cases we know they aren't correct because there are discrepancies in experiments that shouldn't exist, but no model better fits the data and resolves the discrepancies. At no point can science say "this model is how reality must work". But that is somewhat scary. It is scary to think the truth is unknowable and at best we will have an ever better approximation, so people find it simpler to treat that approximation as truth.

luc4sdreyer 3y ago

>from one point in space - We have multiple observatories on and around the planet - The Earth is moving around the Sun - The Sun is moving around the centre of the galaxy - The galaxy is moving towards the great attractor, etc The Copernican principle states that humans, on the Earth or in the Solar System, are not privileged observers of the universe, that observations from the Earth are representative of observations from the average position in the universe. This has been tested in various ways: https://en.wikipedia.org/wiki/Copernican_principle#Tests_of_the_principle https://en.wikipedia.org/wiki/Copernican_principle#Tests_of_... A nice PBS spacetime video about the topic: https://www.youtube.com/watch?v=q-6oU3jXAho https://www.youtube.com/watch?v=q-6oU3jXAho You can also ask how do we know that the laws of physics haven't changed over time. We don't. But at some point you have to make a few basic assumptions in order to have any hope of making scientific progress.

mr_mitm 3y ago

> “as far as we can possibly tell from the data we have” Isn't that self evident in all cases? In cosmology, the implicit assumptions are the Corpernican principle and that GR is correct. That is covered in introductory texts, but unless stated otherwise, it is usually not mentioned, especially not in press releases. I mean, maybe you're just a Boltzmann brain floating in space and nothing is real. Fun to think about, sure, but expecting to state the basics in any and all cases is unrealistic.

pfannkuchen 3y ago
I’m not talking about physics being different in different places. I’m talking about the signal we are getting from far away quite likely being altered between its origin and when it gets to us. Different branches of science have vastly different degrees of certainty. I don’t feel there is sufficient effort put towards communicating this well to the public, especially with respect to the Big Bang, and that annoys me because lay people seem to use it as a factual version of an origin myth when really it probably isn’t any more factual than any other random myth you could pick. It’s very irresponsible to replace the cultural origin myth, which is psychologically important to humans. The whole “explosion from nothing” myth may actually be contributing to modern people’s feelings of meaninglessness.

SkyBelow 3y ago

Yes, there is such an implicit caveat on all of science. Science at its core runs on a repeated process of collect some data, explain it, collect some more data, explain it as well, and keep repeating forever. The scientific model you are likely more familiar with refines this a bit where you use the current model and data to direct where you spend your time/funding collecting more data, but that is mostly a heuristic. Sometimes a person going off on their own will find something amazing to bring back, but we have to remember that many others spend their entire lives and end up finding nothing new or noteworthy. One problem with science literacy is that too many people treat the existing models as true, even when they aren't. In some cases we know they aren't correct because there are discrepancies in experiments that shouldn't exist, but no model better fits the data and resolves the discrepancies. At no point can science say "this model is how reality must work". But that is somewhat scary. It is scary to think the truth is unknowable and at best we will have an ever better approximation, so people find it simpler to treat that approximation as truth.