13 ms·

Is that true? In the way you see a bullet then hear it, can the reverse happen with space events where light reaches you then something else? I don't know anyth

Is that true? In the way you see a bullet then hear it, can the reverse happen with space events where light reaches you then something else? I don't know anything about this other than light is the faster we can travel so assuming we can see things before the effects hit us...

asark 7y ago
75x... factor in the inverse cube law... yeah I'm gonna say unless it's somehow a directed effect it's still won't even be close to mattering a little bit, even if there is some sub-light "wave" of some kind coming toward us from this event. [EDIT] inverse square, that is. My bad.
CobrastanJorji 7y ago
Most of the stuff we observe that comes from space moves at the speed of light. Light, radiative heat, gravity. There are plenty of slower-moving things, like rocks and stellar wind, but it's hard to meaningfully measure that stuff directly for distant stars.
kaibee 7y ago
So two potential scenarios: A. Earth is going to be hit by a super-mega-death laser focusing the entire power output of a star into a concentrated beam. B. A long long time ago, a very dense moon was very far from a supernova. Unfortunately, far is relative, and so is speed in space. Specifically, relative to Earth, the moon is now traveling 5% the speed of light and is on a collision course. In scenario A, there is no way for us to see this coming, because information also cannot travel faster than light. The light is what kills us. In scenario B, it is theoretically possible to see this rogue-moon coming, since it is possible for light to reflect off of it and reach us before the moon does.
- m_mueller 7y ago
  Interesting hypothesis B. Can there be a zone around a supernova where it is strong enough to accelerate planetary objects but weak enough to not just turn them into dust and gas?
  - rocqua 7y ago
    Does it matter if it turns into dust or gas? As long as it stays clumped enough, we might still be screwed.
    - m_mueller 7y ago
      I'd assume once a moon is a bunch of dust, it disperses so fast that what arrives in our solar system is not an issue for us, just part of the background galactic cloud.
rhinokungfu 7y ago
Speed of light is not really just speed of light, but universal speed limit of causality. Light (electromagnetic waves just happens to be one of the few things capable of hitting that limit. Even the effect of gravity is limited to speed of light. PBS Space time has a good video on this - https://www.youtube.com/watch?v=msVuCEs8Ydo&t=5s https://www.youtube.com/watch?v=msVuCEs8Ydo&t=5s. So to answer your question, no it is not possible for anything to affect us any faster than the universal speed limit of causality (that light happens to be able to hit).
- internet_person 7y ago
  There is at least one known exception: neutrinos from a supernova. (Don't get too excited, this doesn't contradict Einstein, as we'll see.) In the hot, dense core of a supernova, photons will scatter around for a while before escaping. Neutrinos, which interact much less often than photons, and travel also more or less at the speed of light, get out basically right away. The difference can be as much as a few hours! Of course it's the high-energy photons that are more dangerous, so the neutrinos are really more like an early-warning system. See e.g.: https://en.wikipedia.org/wiki/SN_1987A https://en.wikipedia.org/wiki/SN_1987A
  - oAlbe 7y ago
    That's still not an exception though. Neutrinos escape first by virtue of the fact that they don't interact with matter and don't bounce around, while light does. They aren't travelling faster than light, just travelling a shorter distance.
    - xmprt 7y ago
      The question wasn't about how fast neutrinos can travel but whether we can detect something before we see it.
      - onetimemanytime 7y ago
        So x event happened 550,000 years ago and the radiation from it might kill us. You say that we may get a warning from neutrinos before the harmful stuff kills us?
0xdeadbeefbabe 7y ago
It's more scientific to hypothesize after the calamity happens.

asark 7y ago

75x... factor in the inverse cube law... yeah I'm gonna say unless it's somehow a directed effect it's still won't even be close to mattering a little bit, even if there is some sub-light "wave" of some kind coming toward us from this event. [EDIT] inverse square, that is. My bad.

CobrastanJorji 7y ago

Most of the stuff we observe that comes from space moves at the speed of light. Light, radiative heat, gravity. There are plenty of slower-moving things, like rocks and stellar wind, but it's hard to meaningfully measure that stuff directly for distant stars.

kaibee 7y ago

So two potential scenarios: A. Earth is going to be hit by a super-mega-death laser focusing the entire power output of a star into a concentrated beam. B. A long long time ago, a very dense moon was very far from a supernova. Unfortunately, far is relative, and so is speed in space. Specifically, relative to Earth, the moon is now traveling 5% the speed of light and is on a collision course. In scenario A, there is no way for us to see this coming, because information also cannot travel faster than light. The light is what kills us. In scenario B, it is theoretically possible to see this rogue-moon coming, since it is possible for light to reflect off of it and reach us before the moon does.

m_mueller 7y ago
Interesting hypothesis B. Can there be a zone around a supernova where it is strong enough to accelerate planetary objects but weak enough to not just turn them into dust and gas?
- rocqua 7y ago
  Does it matter if it turns into dust or gas? As long as it stays clumped enough, we might still be screwed.
  - m_mueller 7y ago
    I'd assume once a moon is a bunch of dust, it disperses so fast that what arrives in our solar system is not an issue for us, just part of the background galactic cloud.

rhinokungfu 7y ago

Speed of light is not really just speed of light, but universal speed limit of causality. Light (electromagnetic waves just happens to be one of the few things capable of hitting that limit. Even the effect of gravity is limited to speed of light. PBS Space time has a good video on this - https://www.youtube.com/watch?v=msVuCEs8Ydo&t=5s https://www.youtube.com/watch?v=msVuCEs8Ydo&t=5s. So to answer your question, no it is not possible for anything to affect us any faster than the universal speed limit of causality (that light happens to be able to hit).

internet_person 7y ago
There is at least one known exception: neutrinos from a supernova. (Don't get too excited, this doesn't contradict Einstein, as we'll see.) In the hot, dense core of a supernova, photons will scatter around for a while before escaping. Neutrinos, which interact much less often than photons, and travel also more or less at the speed of light, get out basically right away. The difference can be as much as a few hours! Of course it's the high-energy photons that are more dangerous, so the neutrinos are really more like an early-warning system. See e.g.: https://en.wikipedia.org/wiki/SN_1987A https://en.wikipedia.org/wiki/SN_1987A
- oAlbe 7y ago
  That's still not an exception though. Neutrinos escape first by virtue of the fact that they don't interact with matter and don't bounce around, while light does. They aren't travelling faster than light, just travelling a shorter distance.
  - xmprt 7y ago
    The question wasn't about how fast neutrinos can travel but whether we can detect something before we see it.
    - onetimemanytime 7y ago
      So x event happened 550,000 years ago and the radiation from it might kill us. You say that we may get a warning from neutrinos before the harmful stuff kills us?

0xdeadbeefbabe 7y ago

It's more scientific to hypothesize after the calamity happens.