4 ms·

But the observable universe roughly is.

by pests 2y ago

vlovich123 2y ago
The observable universe is an illusory artifact of being an observer traveling at less than the speed of light. A constant distance in every direction is a sphere. That tells us nothing about the actual structure of the universe. In other words, your observable universe is different than mine and that's both spheres we're in the middle of. That suggests the universe itself probably isn't a sphere.
- SkyBelow 2y ago
  Is it an illusory artifact or is it all that exists? If it can't be observed, it can't be tested, it can't be verified in any way or ever interacted with, then isn't it just an instances of Russell's Teapot and thus does not exist? What does it mean for science if existence isn't a binary property or one that we set as a truth yet is entirely untestable?
  - pixl97 2y ago
    From all we can tell at this point is the universe is flat. https://en.wikipedia.org/wiki/Shape_of_the_universe https://en.wikipedia.org/wiki/Shape_of_the_universe
  - vlovich123 2y ago
    We definitely have reason to believe that there’s universe outside the observable universe. The CMB uniformity suggests that that’s the case as do our theoretical models. The mere fact that two observers have different observable universes indicates it is indeed an illusory artifact. Just because something is untestable today doesn’t mean it will be for all time. However, the untestability problem has started to creep much more deeply into cosmology and high particle physics in particular - our technology and models aren’t staying enough ahead to provide a lot of fertile testable ground.
    - SkyBelow 2y ago
      >Just because something is untestable today doesn’t mean it will be for all time. This is generally true, but such ideas are kept outside the realm of science until they are. In this case specifically, all our knowledge points to this remaining untestable as it would require FTL travel which is on par with violating conservation of energy or time travel. It even allows solving the halting problem (Turing machine in timeloop until it halts, you outside of the timeloop can then check if the Turing machine in the timeloop ever left it). It is entirely possible that there are things which are true which science cannot verify because of the underlying philosophy by which science operates. Things that exist outside of the observable universe, if FTL travel is truly impossible, would fall outside the realm of science. >The mere fact that two observers have different observable universes indicates it is indeed an illusory artifact. Do they? The nature of the observable universe is that, if you can communicate with someone else, any information they can receive and pass on to you is part of your observable universe as all information travels at the speed of light or slower. If they can receive information and cannot pass it on to you, they are not part of your observable universe any longer and no longer exist (exception if FTL interactions are discovered). Thus the only observers that exist in a way you can interact with, can make any testable hypothesis concerning, and thus can be considered by science, are observers in your observable universe.
      - vlovich123 2y ago
        > Do they? The nature of the observable universe is that, if you can communicate with someone else, any information they can receive and pass on to you is part of your observable universe as all information travels at the speed of light or slower. If they can receive information and cannot pass it on to you, they are not part of your observable universe any longer and no longer exist (exception if FTL interactions are discovered). Thus the only observers that exist in a way you can interact with, can make any testable hypothesis concerning, and thus can be considered by science, are observers in your observable universe. The observable universe is defined as natural light reaching us. It says nothing about repeaters. If someone id at the edge of your observable universe they could still send you a message. They’re observable universe would necessarily include light that wouldn’t reach you due to expansion. Of course, it is possible we’re within a black hole or some other weird space time geometry in which the universe folds in on itself in which case it is possible the observable universe is the universe. I’m not saying that’s impossible since we don’t know. I’m simply stating my Bayesian priors based on my understanding of the evidence collected so far about the CMB and what it and the theoretical models we have suggest. It doesn’t make other theories less valid, it just means where I’d make a wager if I had to. As you say, right now it’s not capable of being a scientific theory and it’s a stretch to even be called a hypothesis. Still, this is just a reversion to our natural state where we have philosophical ideas grounded in the best knowledge we have trying to find ways to unlock the secrets, not unlike ancient Greeks. We might succeed or we might not but I still think it’s a scientific pursuit grounded in the scientific method in some way. For example, we have no way of really confirming whether our models are correct about estimating the distance to stars. Still, we think it’s true enough because it works locally. Science is and always has been a fuzzy endeavor of truth seeking and only local models of simple interactions have a “nonexistent” amount of error.

But the observable universe roughly is.

by pests 2y ago

But the observable universe roughly is.

The observable universe is an illusory artifact of being an observer traveling at less than the speed of light. A constant distance in every direction is a sphere. That tells us nothing about the actual structure of the universe. In other words, your observable universe is different than mine and that's both spheres we're in the middle of. That suggests the universe itself probably isn't a sphere.

SkyBelow 2y ago
Is it an illusory artifact or is it all that exists? If it can't be observed, it can't be tested, it can't be verified in any way or ever interacted with, then isn't it just an instances of Russell's Teapot and thus does not exist? What does it mean for science if existence isn't a binary property or one that we set as a truth yet is entirely untestable?
- pixl97 2y ago
  From all we can tell at this point is the universe is flat. https://en.wikipedia.org/wiki/Shape_of_the_universe https://en.wikipedia.org/wiki/Shape_of_the_universe
- vlovich123 2y ago
  We definitely have reason to believe that there’s universe outside the observable universe. The CMB uniformity suggests that that’s the case as do our theoretical models. The mere fact that two observers have different observable universes indicates it is indeed an illusory artifact. Just because something is untestable today doesn’t mean it will be for all time. However, the untestability problem has started to creep much more deeply into cosmology and high particle physics in particular - our technology and models aren’t staying enough ahead to provide a lot of fertile testable ground.
  - SkyBelow 2y ago
    >Just because something is untestable today doesn’t mean it will be for all time. This is generally true, but such ideas are kept outside the realm of science until they are. In this case specifically, all our knowledge points to this remaining untestable as it would require FTL travel which is on par with violating conservation of energy or time travel. It even allows solving the halting problem (Turing machine in timeloop until it halts, you outside of the timeloop can then check if the Turing machine in the timeloop ever left it). It is entirely possible that there are things which are true which science cannot verify because of the underlying philosophy by which science operates. Things that exist outside of the observable universe, if FTL travel is truly impossible, would fall outside the realm of science. >The mere fact that two observers have different observable universes indicates it is indeed an illusory artifact. Do they? The nature of the observable universe is that, if you can communicate with someone else, any information they can receive and pass on to you is part of your observable universe as all information travels at the speed of light or slower. If they can receive information and cannot pass it on to you, they are not part of your observable universe any longer and no longer exist (exception if FTL interactions are discovered). Thus the only observers that exist in a way you can interact with, can make any testable hypothesis concerning, and thus can be considered by science, are observers in your observable universe.
    - vlovich123 2y ago
      > Do they? The nature of the observable universe is that, if you can communicate with someone else, any information they can receive and pass on to you is part of your observable universe as all information travels at the speed of light or slower. If they can receive information and cannot pass it on to you, they are not part of your observable universe any longer and no longer exist (exception if FTL interactions are discovered). Thus the only observers that exist in a way you can interact with, can make any testable hypothesis concerning, and thus can be considered by science, are observers in your observable universe. The observable universe is defined as natural light reaching us. It says nothing about repeaters. If someone id at the edge of your observable universe they could still send you a message. They’re observable universe would necessarily include light that wouldn’t reach you due to expansion. Of course, it is possible we’re within a black hole or some other weird space time geometry in which the universe folds in on itself in which case it is possible the observable universe is the universe. I’m not saying that’s impossible since we don’t know. I’m simply stating my Bayesian priors based on my understanding of the evidence collected so far about the CMB and what it and the theoretical models we have suggest. It doesn’t make other theories less valid, it just means where I’d make a wager if I had to. As you say, right now it’s not capable of being a scientific theory and it’s a stretch to even be called a hypothesis. Still, this is just a reversion to our natural state where we have philosophical ideas grounded in the best knowledge we have trying to find ways to unlock the secrets, not unlike ancient Greeks. We might succeed or we might not but I still think it’s a scientific pursuit grounded in the scientific method in some way. For example, we have no way of really confirming whether our models are correct about estimating the distance to stars. Still, we think it’s true enough because it works locally. Science is and always has been a fuzzy endeavor of truth seeking and only local models of simple interactions have a “nonexistent” amount of error.