5 ms·

> do we account for velocity in determining whether light traveling at c towards earth will ever reach us? No, because the speed of light is constant for all o

> do we account for velocity in determining whether light traveling at c towards earth will ever reach us? No, because the speed of light is constant for all observers. From our frame of reference on earth, light from distant receding galaxies is always moving towards us at exactly the speed of light, c. Those galaxies also observe the light moving away from them at exactly c. That seems contradictory and unintuitive, that two observers moving away from each other both measure light moving c relative to themselves, but that’s reality. It’s another measurement that changes: if c is always constant, then it must be the passage of time and the distance travelled that we observe differently.

pigpang 3y ago
> That seems contradictory and unintuitive, that two observers moving away from each other both measure light moving c relative to themselves, but that’s reality. Light is a wave. Photon is a complex thing (Hopfion?), but it's a wave, so it waves something, a medium. Speed of wave propagation in a medium is constant. IMHO, it's intuitive.
- mrguyorama 3y ago
  >but it's a wave, so it waves something, a medium. Which was unobserved in the michleson-morely experiment and other followup experiments because....?
  - pigpang 3y ago
    LIGO/Virgo are better version of Michelson-Morely experiment. Gravitational waves are found, so existence of a medium is confirmed.
    - mrguyorama 3y ago
      Gravitational waves existing doesn't confirm the existence of a medium any more than discovering light behaves like a wave confirms the existence of the aether. If you want to posit that light has a medium, you need to redo 100 years of physics, so start showing your work. You mention elsewhere "doing a calculation", and that's just not nearly good enough. You want to overturn perfectly working physics, you NEED to show up with receipts. That's table stakes.

pigpang 3y ago

> That seems contradictory and unintuitive, that two observers moving away from each other both measure light moving c relative to themselves, but that’s reality. Light is a wave. Photon is a complex thing (Hopfion?), but it's a wave, so it waves something, a medium. Speed of wave propagation in a medium is constant. IMHO, it's intuitive.

mrguyorama 3y ago
>but it's a wave, so it waves something, a medium. Which was unobserved in the michleson-morely experiment and other followup experiments because....?
- pigpang 3y ago
  LIGO/Virgo are better version of Michelson-Morely experiment. Gravitational waves are found, so existence of a medium is confirmed.
  - mrguyorama 3y ago
    Gravitational waves existing doesn't confirm the existence of a medium any more than discovering light behaves like a wave confirms the existence of the aether. If you want to posit that light has a medium, you need to redo 100 years of physics, so start showing your work. You mention elsewhere "doing a calculation", and that's just not nearly good enough. You want to overturn perfectly working physics, you NEED to show up with receipts. That's table stakes.