...and the sun suddenly vanished!

hyree_hybrid

I raised this question among my Facebook friends a while back and reached to a closure. Just thought I could extend the discussion with you guys!

Solar ray, even at the speed of light c, takes about 8 minutes to reach the earth from the sun. The earth revolves around the sun in its fixed orbit. From the earth, we can sense the sun's gravitational pull.

And if the sun were to suddenly vanished, will the earth:
a) temporarily orbits around nothing for a brief 8 minutes, or
b) quickly get thrown off its orbital path

If a, how? really? wow!
If b,  then it means we immediately sensed that the sun is no longer there, which also means we've got the information much quicker than the speed of light. But nothing could exceed the speed of light (including information), or could it?

muffins

errk.. x paham...

expelin pliss....:cf:

pinklollipop

macam mana boleh vanished?
ni about gerhana matahari ke?

reez54

hmmm....that sounds a bit impossible coz the sun wont suddenly dissapear out of nothing, coz the sun itself is some form of energy so energy wont just vanish just like that, energy cant be created or be destroyed.

But if that happens for any reason, haha..i think our planet gonna fly away first into d space...weeeeee

me_ai

the situation mention in the question very much relate to the graviational effect/ dynamics of the forces in solar system. hardly to relate with the speed of light.

it seems the (a) is more to answer the question however, i believe the 8 minutes are not the exact time which the earth respond to the 'vanishing' of the pulling forces in order to orbit the sun.

considering the huge graviational pull from the sun earlier, the effect to stay in the orbit may last what, maybe more than just 8  min (depend on  the calculation).

in situation mention as the sun no longer exist, the orbit is not a correct term. the object (earth) must be considered moving in a free trajectory line (assuming no other pulling forces in solar system strong enoguh to interfere the trajectory line) depending on the direction of the forces last applied to the object.

will try to find 1 example to explain this concept.

hyree_hybrid

5# me_ai

Thanks for the reply, me_ai. The point I'm trying to question here is force propagates at finite speed <= speed of light.

Say I have a 300,000km long stick, so extremely light that I can balance one end in my palm, and the other end protruding into the sky. If I jerk the my hand a bit, will the other end get jerked instantaneously? Or will the effect come only seconds later?

EJ

1# hyree_hybrid

vanished yg camne ek? tetiba hilang? ataupun meletup? ataupun yg lelain?

nak ++++ apa yg cik me_ai habaq @post #5 tu ..

rasanya kalau awok maksudkan 'vanished' = hilang; mungkin aa kesannya macam apa yg me_ai habaq tu
tapi kalau awok maksudkan 'vanished' = meletup; kesannya mungkin lain sikit kot ..

yeah, berdasarkan kepada kelajuan cahaya, kita kat bumi akan nampak kesannya kalau aa matahari meletup
macam .. supernova jugak .. kita akan nampak cahaya yg sangat terang kat langit

TAPI .. itu pun kalau impact daripada letupan (serpihan matahari & shockwave) tak sampai dulu aa kan
kalau impact2 tu yg sampai dulu, tak sempat aa kita nak nampok cahaya tu

kalau kesan yg lelain - contohnya macam bumi-orbit - rasanya kesan serta merta KOT
sebab selain daripada takde lagi tarikan graviti matahari yg kekalkan orbit bumi, kita kena tengok faktor2 lain jugaks
contohnya macam .. apa yg jadi kat planet2 yg lebih dekat ngan matahari? rasanya akan hancur jugak
& impactnya akan kena kat bumi .. mungkin akan menyebabkan bumi 'melayang' ke angkasa raya
kalau bumi berlanggar ngan planet2 lain, dah jadi satu hal lak kan .. sbb yg mengelilingi matahari bukannya bumi je kan

rasanya lepas tu pun bumi takkan survive lama sangat kot .. sbb takde lagi keseimbangan pada pasang/surut lautan
mungkin akan menyebabkan perubahan serta merta pada cuaca & apa saja yg berada di langit-bumi-jua diantaranya

me_ai

6# hyree_hybrid

so to compare to event relating to
1. rays of sunlight travelling 300 000km.
2. movement of the stick which is 300 000km length, what will the effect of the stick in one end when a force is applied at the other end

i believe that in 1 sec (roughly) the light will reach this 300 000km.
and i also believe that while the stick been push in 1 end, the other will reacts instantly due to movement, should e less than 1 sec

further explaination;
1. light must travel 300 000km from the start point to the other point, and we all know that it will only 1 sec for it to reach those distant.
2. while for the stick whic has length of 300 000km, let say we apply enough force to let it move 1 mm at the first end, how many distant does the other end need to trahvel, suppose if we neglect other forces that may be influenced the result,  the other end must also travelling the same distant of 1mm. this may be considered less than 1 sec. the difference in the travelling lenght used to differentiate the results.

this is what i try to understand in your 2nd post

hyree_hybrid

8# me_ai

Therefore, from what I understand in your explanation, a displacement at the stick's one end will instantaneously trigger the same displacement at the other end; even light must take 1 sec.

But wouldn't that defy the law saying "Nothing could travel faster than speed of light"? Not even information.

If this is true, then I could communicate with someone in Pluto using a stick spanning across the planets, applying Morse Code by jerking the stick. Because this is faster than via electromagnetic waves which must be lagging seconds apart.

Weird isn't it?

me_ai

1. travelling distant of the waveform = 300 000km
2. travelling of the stick 1mm, reaction from the movement must also 1mm reaction time should be less than 1 sec, not that the travelling of the stick on the 300 000km less than 1 sec.

if you communicate using a material that transfer waveform (ideally using the ray of sunlight) in its substance, let say 300 000km is travelling distant, the time taken should be more. why,
1. waveform on empty space travel faster.
2. a distant of 300 000km are still need to be completed to reach the other end.

diffrent from
reaction of 1 end of stick, which move 1mm, and the other end move 1mm.it does not have to travel a 300 000km distant.

hyree_hybrid

1# hyree_hybrid

vanished yg camne ek? tetiba hilang? ataupun meletup? ataupun yg lelain?

nak ++++ apa yg cik me_ai habaq @post #5 tu ..

rasanya kalau awok maksudkan 'vanished' = hilang; mun ...
EJ Post at 27-9-2009 02:57

Sorry ye kalau post ni terkonpiuskan orang hehehe . Saya memang sedang mengabaikan planet2 sebenar, supernova lah, meletup lah, survival of the planet etc.. Instead, saya sedang mengexplore relationship antara space, gravity, universal speed limit etc..  

The main point is that, boleh ke FORCE bergerak lebih laju dari cahaya (in this case gravitational force lah). Kalau boleh, nescaya kalau matahari tiba2 hilang, kita dah boleh detect akan kehilangannya (by being thrown off orbit) sebelum kita NAMPAK sendiri matahari tu dah takde .

me_ai

utk travelling betwen distance....the light is the fastest among all...known to men.

if in any case the sun suddenly not at where it is place now,
we will first experience darkness (no lights), then later our planet will drift from its orbiting lline, and move in trajectory line.

hyree_hybrid

if in any case the sun suddenly not at where it is place now, we will first experience darkness (no lights), then later our planetwill drift from its orbiting lline, and move in trajectory line. me_ai Post at 27-9-2009 12:41

Yes. It shows that we're still feeling the force the moment the sun is gone. Which means that the "NO FORCE" had to travel over the distance before we can feel there's no longer any. Which means propagation of force (or lack thereof) has a finite speed.

This should be where the term "gravitational wave" comes into place. I did read somewhere on this board about Space-Time fabric/curvature, which serves as the basis for current gravity theory. When throwing a bowling ball onto a giant mattress, the wave ripples outwards. Time elapsed as any surrounding object would start feel the effect.

And the speed of this wave? In a vacuum, I believe it equals to  c!

me_ai

to know how powerful the gravity is...
an object with enough  gravity force, able to bend light path, this is true as there are experiment done on this subject, thoery was develped by einstein.

a black hole also able to 'suck' the light.

EJ

If the Sun mysteriously vanished, what would happen to the Earth?

If the Sun were to suddenly vanish at this very moment, the light from theSun would continue to arrive for the next 8.5 minutes which is thetravel time from the Sun to the Earth at the speed of light.

There wouldstill be a Sun in the sky even though the Sun is actually not there now.

So far as we know, and so far as the little data we have can tell us, gravityand the force of gravity also travels at the speed of light. This means theSun's gravitational force takes 8.5 minutes to cross the solar system to getto the Earth and affect the orbit of the Earth.

If the Sun were to vanish,the gravitational force that it emitted before vanishing would still be onits way and would not stop coming for 8.5 minutes after the Sun had been removed.

Would we see anything interesting happen to the orbits of Mercury and Venusthat would alert us to the fact that the Sun had gone away? No. At least not right away.

The fastest that the effects could reach us would be at the speed of light.Any effects we would see upon the other planets would take LONGER toget to us because the planets would be farther away from us than 8.5light minutes.

If Mercury were very close in the sky to the Sun, the effect would firsthave to get to Mercury, then the light from the planet would have to get to us.

This total distance from sun to Mercury and Mercury to Earth would never beshorter than the direct travel distance of the effect to the Earth.

Looking out at the sky, we would feel nothing at all as the Sun winked outexcept that it suddenly got a whole lot colder.

Daytime wouldbecome nighttime in the blink of an eye, and as we looked at the planetsMercury and Venus over the course of a few hours or days, we would see themdeparting more and more from their previous orbits as they suddenlyfind themselves traveling 'in a straight line' tangent to their previous orbits, at the orbital speed they used to have.



source : http://www.astronomycafe.net/qadir/q629.html

hyree_hybrid

source : http://www.astronomycafe.net/qadir/q629.html
EJ Post at 28-9-2009 00:29

Ahh! Dah ada pun orang cerita pasal benda ni! Thank you x3 !

As for the stick, I think the right term for it should be "shock wave", that the molecules compress and decompress, propagating the force in a finite speed, depending on the elasticity of the stick material. Sure enough, it is slower than speed of light! So by jerking the stick, the other end will only move moments later.

aku_EnSeM

the earth would revolve around the vanishing sun for 8 minutes... according to general relativity, gravitational wave moves at the speed of light, so when the sun disappeared now, the gravitational wave stops and the remaining wave continues to move towards the earth as if the sun still existed. So the earth would still bounded in the orbit. A is the answer.