5 ms·

No, it's not. From our frame of reference (which, in General Relativistic terms, defines a coordinate system with a time coordinate) it still happened 26,000 ye

No, it's not. From our frame of reference (which, in General Relativistic terms, defines a coordinate system with a time coordinate) it still happened 26,000 years ago. If your friend tells you today about how they did X yesterday, would you also argue X happened today from your frame of reference?

wolfendin 4y ago
This confuses the ability to access information about events with the process of accessing information about events. Things happen at the earliest possible moment I could know about them. I was able to get that information about my friend yesterday, I just didn’t. I couldn’t have learned about this 26,000 years ago.
- codethief 4y ago
  I'm not confusing anything. I was merely stating what General Relativity tells us in precise mathematical terms: Time passes between the event of something happening and the event when light/information from that first event first reaches us (or could theoretically reach us). This is reflected by a delta in the time coordinates of the involved events. > Things happen at the earliest possible moment I could know about them. You're of course free to define the word "happen" this way but among physicists you'd be the only one in doing so.
anamexis 4y ago
If you watch your friend do X right in front of you, would you argue it happened yesterday? They're both valid interpretations.
- Supermancho 4y ago
  > If you watch your friend do X right in front of you, would you argue it happened yesterday? If that friend was 671 million miles away, I was say it happened yesterday. If it was a much smaller distance, I can intervene in the event because the relative effects do not prevent me from interacting. > They're both valid interpretations. That's true if you want to accept interpretation without restraint. I prefer consistent interpretations that are compatible with known physics. YMMV
  - anamexis 4y ago
    There are no consistent interpretations! The photon you're seeing that came from 671 million miles travelled to your eye instantly, from its "perspective."
    - codethief 4y ago
      > There are no consistent interpretations! Of course there are. You're confusing the "relativity" part in "General Relativity" with "anything goes" or "anyone can interpret things however they want, without any rules". I have elaborated on this in my other comment to you[0]: > GR is concerned with objective, well-defined statements. Sometimes a statement might depend on the observer (this is relativity after all) but other observers will still be able to predict what that observer will say because there are clear rules to translate observer-dependent statements between observers. So subjective observer-dependent statements can still be objectively true in this sense. [0]: https://news.ycombinator.com/item?id=34946704 https://news.ycombinator.com/item?id=34946704
- LawTalkingGuy 4y ago
  You didn't watch them perform an act in front of you, you watched them on a remote viewing device (telescope, youtube video, etc) which was in front of you. And no, you wouldn't deny it happened yesterday. If you were watching a live event in front of you you'd have the ability to interact with it, such as by asking your friend to stop. If you're viewing something that already happened, you don't have that ability to interact. Quantum theory and relativity aren't tools to decrease our specificity and understanding of the universe so they shouldn't be used to justify "all interpretations are valid" type statements.
  - anamexis 4y ago
    A telescope isn't a remote viewing device, it's photons hitting my eyes just the same as if I were standing directly in front of whatever I'm observing. I'm not trying to do some new-agey "everything is valid" thing here. If I, like the photons, travelled from the source 671 million miles away to Earth at the speed of light, time would not have advanced for me at all. I would be telling you that what you are seeing is happening right this instant. And I would be right! And of course time on Earth has advanced considerably while I was traveling, from Earth's perspective. This is also true.
    - LawTalkingGuy 4y ago
      > A telescope isn't a remote viewing device, it's photons hitting my eyes just the same as if I were standing directly in front of whatever I'm observing. It is a remote viewing device because we're discussing using it to view remote events. And you're trying to say "just the same" despite that there are obviously some differences so it cannot be just the same. Try "somewhat analogously". > If I, like the photons, travelled from the source 671 million miles away to Earth at the speed of light, time would not have advanced for me at all. I would be telling you that what you are seeing is happening right this instant. And I would be right! No, because it took you 1 hour to get here, and if you went back you wouldn't be there at the time you left, so in no way are the events simultaneous. You're only describing subjective experience - and someone who travelled much more slowly in stasis would have the same subjective experience despite their report of objective simultaneity being even more obviously incorrect.
- codethief 4y ago
  > If you watch your friend do X right in front of you, would you argue it happened yesterday? If he is right in front of me, it won't take a day for the light to reach me. So, no, I wouldn't. > They're both valid interpretations. I wasn't talking about subjective interpretations. I was saying that General Relativity clearly distinguishes between the event X of something happening and the event Y of information about that event reaching an observer. X and Y will necessarily be at a timelike or lightlike distance. Therefore, unless this distance is zero, time will necessarily pass between those two events from the perspective of the observer and, in fact, from the perspective of any other observer you could possibly ask, where "observer" is more or less defined by a coordinate system (whose time axis will be the observer's worldline). This is not up for debate.
  - anamexis 4y ago
    > Therefore, unless this distance is zero, time will necessarily pass between those two events from the perspective of the observer No, this is where I disagree. From the perspective of the observer, they are seeing what they are seeing exactly when they see it. They don't perceive any time having passed at all, because we can't perceive an event's age. What's not up for debate is how long it would take to do round-trip communication between the two places. What's also not up for debate is that is impossible to show that these far away events are not happening at the time we see them. How you interpret this is absolutely up for debate, because it's not some intrinsic physical fact.
    - codethief 4y ago
      > No, this is where I disagree. From the perspective of the observer, they are seeing what they are seeing exactly when they see it. They don't perceive any time having passed at all, because we can't perceive an event's age. You are twisting my words and once again interpreting the words "observer" and "event" in a way that deviates from their standard definition in General Relativity. Yes, of course we (as beings with pairs of eyes) will perceive something happening in the sky when we actually see it happening or, more generally, when we first hear about it. This is trivial. That's not a good way to define when something happened, though, because it is highly subjective – depending on whether you received the information through light, gravitational waves, sound, or carrier pigeon, your notion of when something happens will differ greatly. In fact, given that information from the event will typically reach you in multiple ways at the same time (think of lightning & thunder) and sometimes you might focus on one, sometimes on the other, and your brain might process things at different speeds, even if we're just talking about you, this is not a great and consistent definition. Moreover, other people could not predict what times you would ascribe to certain events. This is why General Relativity does not define it that way. GR is concerned with objective, well-defined statements. Sometimes a statement might depend on the observer (this is relativity after all) but other observers will still be able to predict what that observer will say because there are clear rules to translate observer-dependent statements between observers. So subjective observer-dependent statements can still be objectively true in this sense. > What's also not up for debate is that is impossible to show that these far away events are not happening at the time we see them. This is simply not true. How do you think we know that they are actually not happening at the time we see them? Would you also say that it's impossible to prove that the events which cause thunder don't happen at the time you hear the thunder, but earlier, i.e. shortly before you see the lightning? > How you interpret this is absolutely up for debate, because it's not some intrinsic physical fact. You are of course free to interpret all the things you see in the sky or on Earth however you like. The problem is: Given the aforementioned issues with such subjective interpretations, they are essentially useless. We won't be able to agree on anything and won't be able to make reliable predictions. In any case, I was responding to OP who was saying[0] > For all intents and purposes this is happening in real time from our local frame of reference. "Frame of reference" has a precise mathematical meaning: It's a coordinate frame with coordinates that an observer would use to map out their local region of the universe, with some precise rules as to what "mapping out" means. Now this coordinate frame assigns different times to the event X of something happening and the event Y of you receiving light that was emitted at X (again, provided that the distance between the thing that's happening and you is not zero but that's essentially always the case). So from the perspective of our local frame of reference, whatever we see in the sky is not happening in real time. In hindsight, I should have maybe omitted the second half of my comment > If your friend tells you today about how they did X yesterday, would you also argue X happened today from your frame of reference? I was merely trying to hint at the fact that the definition "It happens when I perceive it" is, as discussed above, completely and utterly useless, let alone ill-defined. [0]: https://news.ycombinator.com/item?id=34937699 https://news.ycombinator.com/item?id=34937699

wolfendin 4y ago

This confuses the ability to access information about events with the process of accessing information about events. Things happen at the earliest possible moment I could know about them. I was able to get that information about my friend yesterday, I just didn’t. I couldn’t have learned about this 26,000 years ago.

codethief 4y ago
I'm not confusing anything. I was merely stating what General Relativity tells us in precise mathematical terms: Time passes between the event of something happening and the event when light/information from that first event first reaches us (or could theoretically reach us). This is reflected by a delta in the time coordinates of the involved events. > Things happen at the earliest possible moment I could know about them. You're of course free to define the word "happen" this way but among physicists you'd be the only one in doing so.

anamexis 4y ago

If you watch your friend do X right in front of you, would you argue it happened yesterday? They're both valid interpretations.

Supermancho 4y ago
> If you watch your friend do X right in front of you, would you argue it happened yesterday? If that friend was 671 million miles away, I was say it happened yesterday. If it was a much smaller distance, I can intervene in the event because the relative effects do not prevent me from interacting. > They're both valid interpretations. That's true if you want to accept interpretation without restraint. I prefer consistent interpretations that are compatible with known physics. YMMV
- anamexis 4y ago
  There are no consistent interpretations! The photon you're seeing that came from 671 million miles travelled to your eye instantly, from its "perspective."
  - codethief 4y ago
    > There are no consistent interpretations! Of course there are. You're confusing the "relativity" part in "General Relativity" with "anything goes" or "anyone can interpret things however they want, without any rules". I have elaborated on this in my other comment to you[0]: > GR is concerned with objective, well-defined statements. Sometimes a statement might depend on the observer (this is relativity after all) but other observers will still be able to predict what that observer will say because there are clear rules to translate observer-dependent statements between observers. So subjective observer-dependent statements can still be objectively true in this sense. [0]: https://news.ycombinator.com/item?id=34946704 https://news.ycombinator.com/item?id=34946704
LawTalkingGuy 4y ago
You didn't watch them perform an act in front of you, you watched them on a remote viewing device (telescope, youtube video, etc) which was in front of you. And no, you wouldn't deny it happened yesterday. If you were watching a live event in front of you you'd have the ability to interact with it, such as by asking your friend to stop. If you're viewing something that already happened, you don't have that ability to interact. Quantum theory and relativity aren't tools to decrease our specificity and understanding of the universe so they shouldn't be used to justify "all interpretations are valid" type statements.
- anamexis 4y ago
  A telescope isn't a remote viewing device, it's photons hitting my eyes just the same as if I were standing directly in front of whatever I'm observing. I'm not trying to do some new-agey "everything is valid" thing here. If I, like the photons, travelled from the source 671 million miles away to Earth at the speed of light, time would not have advanced for me at all. I would be telling you that what you are seeing is happening right this instant. And I would be right! And of course time on Earth has advanced considerably while I was traveling, from Earth's perspective. This is also true.
  - LawTalkingGuy 4y ago
    > A telescope isn't a remote viewing device, it's photons hitting my eyes just the same as if I were standing directly in front of whatever I'm observing. It is a remote viewing device because we're discussing using it to view remote events. And you're trying to say "just the same" despite that there are obviously some differences so it cannot be just the same. Try "somewhat analogously". > If I, like the photons, travelled from the source 671 million miles away to Earth at the speed of light, time would not have advanced for me at all. I would be telling you that what you are seeing is happening right this instant. And I would be right! No, because it took you 1 hour to get here, and if you went back you wouldn't be there at the time you left, so in no way are the events simultaneous. You're only describing subjective experience - and someone who travelled much more slowly in stasis would have the same subjective experience despite their report of objective simultaneity being even more obviously incorrect.
codethief 4y ago
> If you watch your friend do X right in front of you, would you argue it happened yesterday? If he is right in front of me, it won't take a day for the light to reach me. So, no, I wouldn't. > They're both valid interpretations. I wasn't talking about subjective interpretations. I was saying that General Relativity clearly distinguishes between the event X of something happening and the event Y of information about that event reaching an observer. X and Y will necessarily be at a timelike or lightlike distance. Therefore, unless this distance is zero, time will necessarily pass between those two events from the perspective of the observer and, in fact, from the perspective of any other observer you could possibly ask, where "observer" is more or less defined by a coordinate system (whose time axis will be the observer's worldline). This is not up for debate.
- anamexis 4y ago
  > Therefore, unless this distance is zero, time will necessarily pass between those two events from the perspective of the observer No, this is where I disagree. From the perspective of the observer, they are seeing what they are seeing exactly when they see it. They don't perceive any time having passed at all, because we can't perceive an event's age. What's not up for debate is how long it would take to do round-trip communication between the two places. What's also not up for debate is that is impossible to show that these far away events are not happening at the time we see them. How you interpret this is absolutely up for debate, because it's not some intrinsic physical fact.
  - codethief 4y ago
    > No, this is where I disagree. From the perspective of the observer, they are seeing what they are seeing exactly when they see it. They don't perceive any time having passed at all, because we can't perceive an event's age. You are twisting my words and once again interpreting the words "observer" and "event" in a way that deviates from their standard definition in General Relativity. Yes, of course we (as beings with pairs of eyes) will perceive something happening in the sky when we actually see it happening or, more generally, when we first hear about it. This is trivial. That's not a good way to define when something happened, though, because it is highly subjective – depending on whether you received the information through light, gravitational waves, sound, or carrier pigeon, your notion of when something happens will differ greatly. In fact, given that information from the event will typically reach you in multiple ways at the same time (think of lightning & thunder) and sometimes you might focus on one, sometimes on the other, and your brain might process things at different speeds, even if we're just talking about you, this is not a great and consistent definition. Moreover, other people could not predict what times you would ascribe to certain events. This is why General Relativity does not define it that way. GR is concerned with objective, well-defined statements. Sometimes a statement might depend on the observer (this is relativity after all) but other observers will still be able to predict what that observer will say because there are clear rules to translate observer-dependent statements between observers. So subjective observer-dependent statements can still be objectively true in this sense. > What's also not up for debate is that is impossible to show that these far away events are not happening at the time we see them. This is simply not true. How do you think we know that they are actually not happening at the time we see them? Would you also say that it's impossible to prove that the events which cause thunder don't happen at the time you hear the thunder, but earlier, i.e. shortly before you see the lightning? > How you interpret this is absolutely up for debate, because it's not some intrinsic physical fact. You are of course free to interpret all the things you see in the sky or on Earth however you like. The problem is: Given the aforementioned issues with such subjective interpretations, they are essentially useless. We won't be able to agree on anything and won't be able to make reliable predictions. In any case, I was responding to OP who was saying[0] > For all intents and purposes this is happening in real time from our local frame of reference. "Frame of reference" has a precise mathematical meaning: It's a coordinate frame with coordinates that an observer would use to map out their local region of the universe, with some precise rules as to what "mapping out" means. Now this coordinate frame assigns different times to the event X of something happening and the event Y of you receiving light that was emitted at X (again, provided that the distance between the thing that's happening and you is not zero but that's essentially always the case). So from the perspective of our local frame of reference, whatever we see in the sky is not happening in real time. In hindsight, I should have maybe omitted the second half of my comment > If your friend tells you today about how they did X yesterday, would you also argue X happened today from your frame of reference? I was merely trying to hint at the fact that the definition "It happens when I perceive it" is, as discussed above, completely and utterly useless, let alone ill-defined. [0]: https://news.ycombinator.com/item?id=34937699 https://news.ycombinator.com/item?id=34937699