4 ms·

2M mph = 900 kps = three one-thousandths of light speed

GuB-42 2y ago
So, really fast, but not what we would consider relativistic. That's may be in the range of speed that is most unfamiliar to us. We get speeds up to orbital velocities, in the 10 km/s range, as these are the "fast" objects we know (rockets, meteorites, ...), and then we get to significant fractions of light speed, mostly in the context of communication. But what goes at 900 km/s in our day to day life? Is it a number we see anywhere besides colliding galaxies?
- perihelions 2y ago
  Not really, https://en.wikipedia.org/wiki/Orders_of_magnitude_(speed) https://en.wikipedia.org/wiki/Orders_of_magnitude_(speed) 440 km/s—"Typical speed of the stepped leader of lightning (cf. return stroke below).[31]" 445 km/s—"Max velocity of the remaining shell (mass about 0.1 mg) of an inertial confinement fusion capsule driven by the National Ignition Facility for the 'Bigfoot' capsule campaign.[32] Current fastest macroscopic human-made system." 1,000 km/s—"Typical speed of a Moreton wave across the surface of the Sun."
  - GuB-42 2y ago
    > 440 km/s—"Typical speed of the stepped leader of lightning (cf. return stroke below).[31]" Good one, I didn't think about that one. It means that galaxies are travelling lightning fast, literally.
- Trellmor 2y ago
  It's also cosmology, but for what it's worth, the solar system is moving at about 230km/s around the milky way so you could say every one of us is moving at such a number.
  - snickerbockers 2y ago
    If you continue down this train of thought you eventually realize that outside of earth, velocity is just a number and all that really matters is the relative velocities of the two. So it's impossible to definitively state which one is moving or if they're both moving and if so how fast each one is moving. And then these sorts of things seem far less impressive. And then it gets weirder when you consider that galaxies don't actually collide at all because they're so sparse and all that really happens is they pass through each other and maybe they permanently merge or maybe some of the matter in one galaxy joins the other one and they just keep drifting apart in slightly different directions.
- TomatoCo 2y ago
  This thought reminds me a lot of the Tesla unit. https://en.wikipedia.org/wiki/Tesla_(unit) https://en.wikipedia.org/wiki/Tesla_(unit) It goes from 3.2 x 10^-5 to 1200 fairly gradually and then suddenly to 10^9. My partner at the time looked at this and remarked "There are some unexplored orders of magnitude" which feels like a good, dramatic phrase.
FredPret 2y ago
c is just crazy fast. But still slow compared to the size of the universe!

So, really fast, but not what we would consider relativistic. That's may be in the range of speed that is most unfamiliar to us. We get speeds up to orbital velocities, in the 10 km/s range, as these are the "fast" objects we know (rockets, meteorites, ...), and then we get to significant fractions of light speed, mostly in the context of communication. But what goes at 900 km/s in our day to day life? Is it a number we see anywhere besides colliding galaxies?

perihelions 2y ago
Not really, https://en.wikipedia.org/wiki/Orders_of_magnitude_(speed) https://en.wikipedia.org/wiki/Orders_of_magnitude_(speed) 440 km/s—"Typical speed of the stepped leader of lightning (cf. return stroke below).[31]" 445 km/s—"Max velocity of the remaining shell (mass about 0.1 mg) of an inertial confinement fusion capsule driven by the National Ignition Facility for the 'Bigfoot' capsule campaign.[32] Current fastest macroscopic human-made system." 1,000 km/s—"Typical speed of a Moreton wave across the surface of the Sun."
- GuB-42 2y ago
  > 440 km/s—"Typical speed of the stepped leader of lightning (cf. return stroke below).[31]" Good one, I didn't think about that one. It means that galaxies are travelling lightning fast, literally.
Trellmor 2y ago
It's also cosmology, but for what it's worth, the solar system is moving at about 230km/s around the milky way so you could say every one of us is moving at such a number.
- snickerbockers 2y ago
  If you continue down this train of thought you eventually realize that outside of earth, velocity is just a number and all that really matters is the relative velocities of the two. So it's impossible to definitively state which one is moving or if they're both moving and if so how fast each one is moving. And then these sorts of things seem far less impressive. And then it gets weirder when you consider that galaxies don't actually collide at all because they're so sparse and all that really happens is they pass through each other and maybe they permanently merge or maybe some of the matter in one galaxy joins the other one and they just keep drifting apart in slightly different directions.
TomatoCo 2y ago
This thought reminds me a lot of the Tesla unit. https://en.wikipedia.org/wiki/Tesla_(unit) https://en.wikipedia.org/wiki/Tesla_(unit) It goes from 3.2 x 10^-5 to 1200 fairly gradually and then suddenly to 10^9. My partner at the time looked at this and remarked "There are some unexplored orders of magnitude" which feels like a good, dramatic phrase.

FredPret 2y ago

c is just crazy fast. But still slow compared to the size of the universe!