Wouldn’t you see the effect on the moon?
8 Minutes
Submitted 3 months ago by fossilesque@mander.xyz to science_memes@mander.xyz
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Comments
friend_of_satan@lemmy.world 3 months ago
Comment105@lemm.ee 3 months ago
Imagine seeing the moon just switch off
friend_of_satan@lemmy.world 3 months ago
That would be a beautiful, terrifying sight. You could gaze up at the most amazing view of the stars as the whole world froze to death.
Rexelpitlum@discuss.tchncs.de 3 months ago
There is a really great short story by Larry Niven based on a similar topic:
“Inconstant Moon”
There is also an “Outer Limits” episode based on this. I watched that before knowing the short story and is one of only 2 or three OL episodes that I still have an active memory of…
tate@lemmy.sdf.org 3 months ago
If you can see the moon (if it is “up” at night).
Kroxx@lemm.ee 3 months ago
Yup
GraniteM@lemmy.world 3 months ago
There’s a pretty cool short story where a guy is looking at the full moon and he realizes that it’s gotten way too bright, and that could only happen because the sun has just spontaneously exploded, and he basically just makes peace with the fact that the world is going to be destroyed very shortly.
Klear@sh.itjust.works 3 months ago
Yeah - half a second before seeing it on the sun.
Redderthanmisty@lemmygrad.ml 3 months ago
Assuming its midday, and the moon is on or near the horizon, it would actually still be seen for an additional 1.3 seconds after we see the sun disappear. If its high in the sky however, it would disappear only a few ms after the sun
niktemadur@lemmy.world 3 months ago
That is actually correct. The difference is a few thousandths of a second, but it is there.
TheBigMike@lemm.ee 3 months ago
It goes up to 9 minutes, since every single communication gadget will yell out that the sun has disappeared as reports come in from the other side of the earth.
Notyou@sopuli.xyz 3 months ago
Depending on the lunar cycle, the night time side would notice the moon become dim.
Klear@sh.itjust.works 3 months ago
Doubt anyone would notice the moon getting dim when the fucking sun disappears in the same second.
cmgvd3lw@discuss.tchncs.de 3 months ago
Now I am curious, somebody explain. if it just stopped burning, would we know after 8 mins, if we lived on the opposite side?
hemko@lemmy.dbzer0.com 3 months ago
Moon would “disappear” when it no longer reflected Sun’s light.
It would also start getting very cold fast
marcos@lemmy.world 3 months ago
It would probably take more than a day for the cold to be so intense that you can’t possibly explain with some normal local phenomenon.
tate@lemmy.sdf.org 3 months ago
The moon might be on the daylight side, so we wouldn’t necessarily observe that.
Routhinator@startrek.website 3 months ago
Any visible planet or asteroid would. So some stars would also appear to blink out, but those would take longer to blink out. So the moon would go after 8 minutes, Jupiter would take 43 minutes to stop receiving light, and another 35-52 minutes to disappear for earth depending on orbital locations.
Presumably we would get something on radio/tv/internet from the side facing the sun once they realized it, that of course being only if they hadn’t already been eradicated by a horrific shockwave caused by whatever event caused the sun to vanish before they had a chance to report what they saw, because supernovae tend to travel at very close to the speed of light, so there wouldn’t be much time for them to react.
And if this is a supernova, you might just have time to grok what happened before the planet was obliterated under your feet from the shockwave.
So I guess… chances are we would just barely understand what happened before we were gone.
Anticorp@lemmy.world 3 months ago
Does heat travel at the speed of light? I just realized I have no idea how the heat from the sun travels to earth.
bluemellophone@lemmy.world 3 months ago
It takes 8 minutes for the light to travel from the sun to Earth. Because light in a vacuum travels faster than anything, including information, we would not and could not know it had disappeared for 8 minutes. This means Earth would continue to follow its orbit around a non-existent sun for 8 minutes because the Sun’s gravity would still be acting on the Earth.
If it was nighttime, you wouldn’t notice the sudden lack of sunlight (other than if it was a full moon) but you’d almost certainly notice the change in gravity.
ironhydroxide@sh.itjust.works 3 months ago
I don’t think you’d actually “notice” the gravity.
Earth would still retain it’s mass, and we’re much closer to it, so it’s lesser mass acts much more on us than the sun’s greater.
Though, the moon would stop orbiting the sun and travel on a mostly tangential path, instead of the elliptical path it currently travels.
This is a very interesting physics question that I may look into further. Specifically what would the theoretical acceleration be, due to the lack of the sun? Is it above a humans level of perception?
cmgvd3lw@discuss.tchncs.de 3 months ago
Interesting, so you are saying light is faster than gravity?
mattreb@feddit.it 3 months ago
you’d almost certainly notice the change in gravity.
Really? can you actually percieve the sun gravity? Do you mean that we would get like a tsunami beause of the tidal effect? Now I kinda want a documentary about this.
abfarid@startrek.website 3 months ago
It’s weird to say that light travels faster than information, because light is information. In other words, top speed for information IS speed of light.
Nakoichi@hexbear.net 3 months ago
Yes, because of the medium of communication you are using right now.
shy_mia@lemmy.blahaj.zone 3 months ago
The moon would disappear though, so you’d notice by looking at the sky if it wasn’t obstructed by clouds.
Darkassassin07@lemmy.ca 3 months ago
Only if the moon is on your side of the planet at the time and not already eclipsed by earth’s shadow.
We are however very connected. That shit would be global news immediately.
Pyr_Pressure@lemmy.ca 3 months ago
I’m more interested in how long before we freeze to death.
How long will the earth’s atmosphere hold onto its heat?
Sauerkraut@discuss.tchncs.de 3 months ago
I’m more interested in how long before we freeze to death.
Kurzegesagt did a great video on this thought experiment: www.youtube.com/watch?v=gLZJlf5rHVs&t=1
charonn0@startrek.website 3 months ago
The classic sci-fi short story A Pale of Air touches on this.
someguy3@lemmy.world 3 months ago
But we do have Twitter now.
LibertyLizard@slrpnk.net 3 months ago
Not anymore…
darki@lemmy.world 3 months ago
Or they will postulate its the left who put up a fake screen on the sky
zea_64@lemmy.blahaj.zone 3 months ago
If the sun disappears when? According to GR’s conception of simultaneous events, it disappears immediately.
tate@lemmy.sdf.org 3 months ago
Which two event are you talking about being simultaneous? The Sun going out and Earthers observing it? Those things will not be simultaneous in any reference frame, because they are “light-like” separated.
WolfLink@sh.itjust.works 3 months ago
I think what he means is when the light from the sun disappearing arrives at earth, that’s effectively when the event of the sun disappearing happened from the earth’s perspective.
Zink@programming.dev 3 months ago
Yep. Imagine you’re off in space such that you, the sun, and the earth make an equilateral triangle. The sun disappears, then after 8 minutes you see it disappear. Then after ANOTHER 8 minutes you see the earth go dark, because that light had to cover two of the 8-light-minute long legs of the triangle.
AidsKitty@lemmy.world 3 months ago
All we can see is 8 minutes into the sun’s past.
Kolanaki@yiffit.net 3 months ago
What if I have a flashlight?
Infamousblt@hexbear.net 3 months ago
Technically true since the daytime side will know first.
Etterra@lemmy.world 3 months ago
Well they’re not entirely wrong… I mean I turn off my notifications when I go to sleep.
shneancy@lemmy.world 3 months ago
unless you’re sleeping - 8 minutes and maybe 30 seconds to start seeing posts online, 10 minutes to start getting news about it
Duamerthrax@lemmy.world 3 months ago
I don’t know about you, but if I start seeing headlines about the Sun vanishing, I’m assuming it’s a hoax and going back to bed.
Darkassassin07@lemmy.ca 3 months ago
Maybe if ony one or two places are reporting on it. If all the major ‘reputable’ news sources are reporting it; there’s a pretty good chance there’s something to it.
shneancy@lemmy.world 3 months ago
then wait until the 10min mark then! Would be rather odd if all news sources in unison decided to pull a prank like that
ekZepp@lemmy.world 3 months ago
if the Sun were to disappear, then instantaneously we’d be flung out of orbit because there’d be no gravitational tug keeping the Earth in orbit around where the Sun used to be.
gerbler@lemmy.world 3 months ago
What I wanna know is if gravitational waves travel at the speed of light all the time or are they influenced by media like light.
Zink@programming.dev 3 months ago
I’m 0% an expert in this, but I think they move at light speed all the time. Light is “affected” by mass only indirectly, since the light travels in a straight line through local space but space itself is curved by the mass.
Tlaloc_Temporal@lemmy.ca 3 months ago
Light gets caught up in mediums because those mediums have electric fields (the electrons for matter, or light itself when interfering). Thus, gravity waves will be slowed by gravity fields, like planets, stars, and galaxies.
What waves interact with also depends on the wavelength, like how radio waves can bounce off Earth’s ionosphere, but can ignore the atoms in the walls of your house. There are plenty of very large gravity waves from merging black holes and neutron stars, and those pass right through Earth. Smaller gravity waves (like from a collapsing or disappearing star) could interact with other stars, possibly reflecting off of star clusters, or even refracting through like glass if the distances were regular and the waves just the right length.
Those waves would also be delayed, just like light in glass, air, or water. Interestingly, even light still moves through these mediums at light-speed, but all it’s energy moves slower. If you had a sensitive enough detector you could see heavily attenuated light that didn’t slow down.
synapse1278@lemmy.world 3 months ago
If I understand that right, gravity also moves in space at the speed of light, therefore Earth will keep on orbiting for 8min around nothing?
vithigar@lemmy.ca 3 months ago
Kind of. The concept of simultaneity breaks down at distances where the speed of light matters. If we base our on what we currently observe and call “now” on the Sun the eight minute old state we currently observe then what does “now” on earth look like from the point of view of the Sun at that same moment? You can’t reconcile a single “now” for observers in both locations.
An alternative take which is also consistent with observable physics is that the speed of light is infinite but it’s causality itself that propagates at c.
Thinking in those terms also makes a number of relativistic effects more intuitive. You need infinite energy to reach the speed of light simply because it’s infinitely fast. Time dilates when moving because you’re encountering approaching causality earlier than you otherwise would have. Time “stops” for anything traveling at the speed of light because at infinite speed it just experiences literally everything in its line of travel at once and the concept of “after” becomes meaningless, encountering all future oncoming causality in a single instant.
This was a bit of a tangent but it’s something that has fascinated me for a long time.
Liz@midwest.social 3 months ago
I’m trying to understand how that reference frame works when you just just bounce a photon off a mirror and time how long it takes to come back? Like, light must have a non-infinite speed to the stationary observer, or it wouldn’t take time to traverse the distance.
curiousaur@reddthat.com 3 months ago
Information can only travel at the speed of light.
abfarid@startrek.website 3 months ago
It’s sort of how if you hold a slinky on one end hanging down, then drop the slinky, bottom will not start falling until the top reaches it. In a sense, bottom will be hanging onto nothing. But of course that nothing is tension from the top of the slinky.
Tyfud@lemmy.world 3 months ago
That was an intuitive way to think about it, thank you.
DogWater@lemmy.world 3 months ago
That is correct as weird as it sounds
BigBenis@lemmy.world 3 months ago
The sun could be gone but its influence would remain. Kinda like getting out of a pool and looking back to see the waves on the surface that you caused.