Can two planets in an empty universe meet/be pulled together?
$begingroup$
For this question assume that the entire universe is completely empty. The universe is not expanding or contracting, it is completely motionless since time immemorial and has never moved before.
Only two identical earths without moon are left in this entire universe and they are 5 billion light years apart. From their starting position the earths do not spin or move at all they are completely motionless.
Would these planets ever meet or at least be pulled together? Or are the their respective gravities too small to have any meaningful effect?
gravity universe observable-universe rogue-planet
asked Feb 9 at 12:08
TomTom
1638
$endgroup$
|
show 4 more comments
$begingroup$
For this question assume that the entire universe is completely empty. The universe is not expanding or contracting, it is completely motionless since time immemorial and has never moved before.
Only two identical earths without moon are left in this entire universe and they are 5 billion light years apart. From their starting position the earths do not spin or move at all they are completely motionless.
Would these planets ever meet or at least be pulled together? Or are the their respective gravities too small to have any meaningful effect?
gravity universe observable-universe rogue-planet
asked Feb 9 at 12:08
TomTom
1638
$endgroup$
1
$begingroup$
For a good 5 billions ly they ignore each other.
$endgroup$
– Alchimista
Feb 9 at 12:34
$begingroup$
I want to say that probably you consider the entire universe as to be the entire visible and/or observable universe. The accepted answer is indeed satisfactory only under several assumption. It is more to answer about two generic masses in a static enormous room. Else cosmology sets in
$endgroup$
– Alchimista
Feb 9 at 12:54
$begingroup$
I am familiar with the differences, but for this question to work i needed to be sure there where no outside factors affecting the two planets.
$endgroup$
– Tom
Feb 9 at 13:24
2
$begingroup$
Is the universe expanding?
$endgroup$
– userLTK
Feb 9 at 15:05
1
$begingroup$
Surely this is more of a physics question?
$endgroup$
– Fattie
Feb 12 at 14:50
|
show 4 more comments
$begingroup$
For this question assume that the entire universe is completely empty. The universe is not expanding or contracting, it is completely motionless since time immemorial and has never moved before.
Only two identical earths without moon are left in this entire universe and they are 5 billion light years apart. From their starting position the earths do not spin or move at all they are completely motionless.
Would these planets ever meet or at least be pulled together? Or are the their respective gravities too small to have any meaningful effect?
gravity universe observable-universe rogue-planet
asked Feb 9 at 12:08
TomTom
1638
$endgroup$
For this question assume that the entire universe is completely empty. The universe is not expanding or contracting, it is completely motionless since time immemorial and has never moved before.
Only two identical earths without moon are left in this entire universe and they are 5 billion light years apart. From their starting position the earths do not spin or move at all they are completely motionless.
Would these planets ever meet or at least be pulled together? Or are the their respective gravities too small to have any meaningful effect?
gravity universe observable-universe rogue-planet
gravity universe observable-universe rogue-planet
asked Feb 9 at 12:08
TomTom
1638
asked Feb 9 at 12:08
TomTom
1638
edited Mar 14 at 20:07
Tom
asked Feb 9 at 12:08
TomTom
1638
asked Feb 9 at 12:08
TomTom
1638
asked Feb 9 at 12:08
TomTom
1638
1638
1
$begingroup$
For a good 5 billions ly they ignore each other.
$endgroup$
– Alchimista
Feb 9 at 12:34
$begingroup$
I want to say that probably you consider the entire universe as to be the entire visible and/or observable universe. The accepted answer is indeed satisfactory only under several assumption. It is more to answer about two generic masses in a static enormous room. Else cosmology sets in
$endgroup$
– Alchimista
Feb 9 at 12:54
$begingroup$
I am familiar with the differences, but for this question to work i needed to be sure there where no outside factors affecting the two planets.
$endgroup$
– Tom
Feb 9 at 13:24
2
$begingroup$
Is the universe expanding?
$endgroup$
– userLTK
Feb 9 at 15:05
1
$begingroup$
Surely this is more of a physics question?
$endgroup$
– Fattie
Feb 12 at 14:50
|
show 4 more comments
1
$begingroup$
For a good 5 billions ly they ignore each other.
$endgroup$
– Alchimista
Feb 9 at 12:34
$begingroup$
I want to say that probably you consider the entire universe as to be the entire visible and/or observable universe. The accepted answer is indeed satisfactory only under several assumption. It is more to answer about two generic masses in a static enormous room. Else cosmology sets in
$endgroup$
– Alchimista
Feb 9 at 12:54
$begingroup$
I am familiar with the differences, but for this question to work i needed to be sure there where no outside factors affecting the two planets.
$endgroup$
– Tom
Feb 9 at 13:24
2
$begingroup$
Is the universe expanding?
$endgroup$
– userLTK
Feb 9 at 15:05
1
$begingroup$
Surely this is more of a physics question?
$endgroup$
– Fattie
Feb 12 at 14:50
1
1
$begingroup$
For a good 5 billions ly they ignore each other.
$endgroup$
– Alchimista
Feb 9 at 12:34
$begingroup$
For a good 5 billions ly they ignore each other.
$endgroup$
– Alchimista
Feb 9 at 12:34
$begingroup$
I want to say that probably you consider the entire universe as to be the entire visible and/or observable universe. The accepted answer is indeed satisfactory only under several assumption. It is more to answer about two generic masses in a static enormous room. Else cosmology sets in
$endgroup$
– Alchimista
Feb 9 at 12:54
$begingroup$
I want to say that probably you consider the entire universe as to be the entire visible and/or observable universe. The accepted answer is indeed satisfactory only under several assumption. It is more to answer about two generic masses in a static enormous room. Else cosmology sets in
$endgroup$
– Alchimista
Feb 9 at 12:54
$begingroup$
I am familiar with the differences, but for this question to work i needed to be sure there where no outside factors affecting the two planets.
$endgroup$
– Tom
Feb 9 at 13:24
$begingroup$
I am familiar with the differences, but for this question to work i needed to be sure there where no outside factors affecting the two planets.
$endgroup$
– Tom
Feb 9 at 13:24
2
2
$begingroup$
Is the universe expanding?
$endgroup$
– userLTK
Feb 9 at 15:05
$begingroup$
Is the universe expanding?
$endgroup$
– userLTK
Feb 9 at 15:05
1
1
$begingroup$
Surely this is more of a physics question?
$endgroup$
– Fattie
Feb 12 at 14:50
$begingroup$
Surely this is more of a physics question?
$endgroup$
– Fattie
Feb 12 at 14:50
|
show 4 more comments
3 Answers
3
active
oldest
votes
$begingroup$
Yes, they would experience gravitational attraction. It would take a long time for them to collide... the formula (derived here and shown here) is:
$$t = frac{pi}{2} sqrt{frac{d^3}{2G(m_1+m_2)}}$$
where $d$ is the initial distance between the two planets of mass $m_1$ and $m_2$ and $G$ is the Gravitational constant. This gives a time of about $10^{23}$ years, much much longer than the universe has existed. This assumes Newtonian mechanics. Relativity would not change the conclusion much.
There is no known upper limit to gravity, and plenty of indirect evidence that it has no upper limit.
edited Feb 28 at 8:21
uhoh
6,95022172
answered Feb 9 at 12:36
James KJames K
34.8k257119
$endgroup$
2
$begingroup$
The collision speed of a test particle falling to Earth from infinity is equal to the escape velocity, about 11 km/s. For 2 Earth-mass bodies, the speed will be similar, I think you can just multiply it by $sqrt 2$, but I'm too sleepy to do the algebra right now. ;)
$endgroup$
– PM 2Ring
Feb 9 at 20:16
$begingroup$
What (indirect) evidence is available that gravity still acts 5 billion light years away?
$endgroup$
– Martijn Weterings
Feb 12 at 21:39
$begingroup$
I just did the algebra. The relative collision speed of 2 Earths is identical to the terminal speed of a test particle, so 11.186 km/s.
$endgroup$
– PM 2Ring
Feb 13 at 21:05
$begingroup$
"long time for them to collide" they'll only collide certainly if they are both "stationary" to begin with, or, have certain relative vectors. if they are moving to begin with, they'll be attracted but in many cases will end up in a (huge, mammoth) orbit around each other.
$endgroup$
– Fattie
Feb 15 at 11:38
$begingroup$
There is still the problem that there is indeed an effective upper limit to gravity. If two objects are too far apart, due to expansion their separation will increase faster than the speed of light. There are parts of the universe that will never experience gravity or light from other parts of the universe. See this answer and answers to Am I attracting Pluto?
$endgroup$
– uhoh
Feb 28 at 8:33
add a comment |
$begingroup$
Yes: Given that the universe isn't expanding at a faster rate than the speed of the gravity effect of those objects, then the gravity effect of them would be able to reach one another.
Even then it would take a very long time for the gravity effects of the objects to reach one another, so the objects would just stay there motionless for ages(in this case 5 billion light years) before starting to move towards eachother.
http://www.nowykurier.com/toys/gravity/gravity.html
answered Feb 9 at 20:22
NoobNoob
113
$endgroup$
1
$begingroup$
The last part isn't ok.At least not in general. See for instance researchgate.net/publication/…. Anyway the Q is edited and a static universe is now specified. So the problem is reduced to test masset at infinity or whatever distance so the answer should be easier
$endgroup$
– Alchimista
Feb 10 at 9:01
add a comment |
$begingroup$
YES!
Gravity will eventually pull them together.
The thing is that gravity exerts itself over very vast distances, although the force decreases exponentially over distance. BUT, two motion less massive objects will attract each other, without any other influence whatsoever.
answered Feb 13 at 5:30
Khawar Ali SherKhawar Ali Sher
62
$endgroup$
3
$begingroup$
"Exponentially" in a casual day to day sense but not in a mathematical sense. Gravitational attraction decays more quickly than inverse linear, doubling the distance more than halves the attraction, but not as fast as exponential. In is inverse quadratic which, in the world of maths, is slow compared to exponential.
$endgroup$
– badjohn
Feb 15 at 9:08
add a comment |
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3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
Yes, they would experience gravitational attraction. It would take a long time for them to collide... the formula (derived here and shown here) is:
$$t = frac{pi}{2} sqrt{frac{d^3}{2G(m_1+m_2)}}$$
where $d$ is the initial distance between the two planets of mass $m_1$ and $m_2$ and $G$ is the Gravitational constant. This gives a time of about $10^{23}$ years, much much longer than the universe has existed. This assumes Newtonian mechanics. Relativity would not change the conclusion much.
There is no known upper limit to gravity, and plenty of indirect evidence that it has no upper limit.
edited Feb 28 at 8:21
uhoh
6,95022172
answered Feb 9 at 12:36
James KJames K
34.8k257119
$endgroup$
2
$begingroup$
The collision speed of a test particle falling to Earth from infinity is equal to the escape velocity, about 11 km/s. For 2 Earth-mass bodies, the speed will be similar, I think you can just multiply it by $sqrt 2$, but I'm too sleepy to do the algebra right now. ;)
$endgroup$
– PM 2Ring
Feb 9 at 20:16
$begingroup$
What (indirect) evidence is available that gravity still acts 5 billion light years away?
$endgroup$
– Martijn Weterings
Feb 12 at 21:39
$begingroup$
I just did the algebra. The relative collision speed of 2 Earths is identical to the terminal speed of a test particle, so 11.186 km/s.
$endgroup$
– PM 2Ring
Feb 13 at 21:05
$begingroup$
"long time for them to collide" they'll only collide certainly if they are both "stationary" to begin with, or, have certain relative vectors. if they are moving to begin with, they'll be attracted but in many cases will end up in a (huge, mammoth) orbit around each other.
$endgroup$
– Fattie
Feb 15 at 11:38
$begingroup$
There is still the problem that there is indeed an effective upper limit to gravity. If two objects are too far apart, due to expansion their separation will increase faster than the speed of light. There are parts of the universe that will never experience gravity or light from other parts of the universe. See this answer and answers to Am I attracting Pluto?
$endgroup$
– uhoh
Feb 28 at 8:33
add a comment |
$begingroup$
Yes, they would experience gravitational attraction. It would take a long time for them to collide... the formula (derived here and shown here) is:
$$t = frac{pi}{2} sqrt{frac{d^3}{2G(m_1+m_2)}}$$
where $d$ is the initial distance between the two planets of mass $m_1$ and $m_2$ and $G$ is the Gravitational constant. This gives a time of about $10^{23}$ years, much much longer than the universe has existed. This assumes Newtonian mechanics. Relativity would not change the conclusion much.
There is no known upper limit to gravity, and plenty of indirect evidence that it has no upper limit.
edited Feb 28 at 8:21
uhoh
6,95022172
answered Feb 9 at 12:36
James KJames K
34.8k257119
$endgroup$
2
$begingroup$
The collision speed of a test particle falling to Earth from infinity is equal to the escape velocity, about 11 km/s. For 2 Earth-mass bodies, the speed will be similar, I think you can just multiply it by $sqrt 2$, but I'm too sleepy to do the algebra right now. ;)
$endgroup$
– PM 2Ring
Feb 9 at 20:16
$begingroup$
What (indirect) evidence is available that gravity still acts 5 billion light years away?
$endgroup$
– Martijn Weterings
Feb 12 at 21:39
$begingroup$
I just did the algebra. The relative collision speed of 2 Earths is identical to the terminal speed of a test particle, so 11.186 km/s.
$endgroup$
– PM 2Ring
Feb 13 at 21:05
$begingroup$
"long time for them to collide" they'll only collide certainly if they are both "stationary" to begin with, or, have certain relative vectors. if they are moving to begin with, they'll be attracted but in many cases will end up in a (huge, mammoth) orbit around each other.
$endgroup$
– Fattie
Feb 15 at 11:38
$begingroup$
There is still the problem that there is indeed an effective upper limit to gravity. If two objects are too far apart, due to expansion their separation will increase faster than the speed of light. There are parts of the universe that will never experience gravity or light from other parts of the universe. See this answer and answers to Am I attracting Pluto?
$endgroup$
– uhoh
Feb 28 at 8:33
add a comment |
$begingroup$
Yes, they would experience gravitational attraction. It would take a long time for them to collide... the formula (derived here and shown here) is:
$$t = frac{pi}{2} sqrt{frac{d^3}{2G(m_1+m_2)}}$$
where $d$ is the initial distance between the two planets of mass $m_1$ and $m_2$ and $G$ is the Gravitational constant. This gives a time of about $10^{23}$ years, much much longer than the universe has existed. This assumes Newtonian mechanics. Relativity would not change the conclusion much.
There is no known upper limit to gravity, and plenty of indirect evidence that it has no upper limit.
edited Feb 28 at 8:21
uhoh
6,95022172
answered Feb 9 at 12:36
James KJames K
34.8k257119
$endgroup$
Yes, they would experience gravitational attraction. It would take a long time for them to collide... the formula (derived here and shown here) is:
$$t = frac{pi}{2} sqrt{frac{d^3}{2G(m_1+m_2)}}$$
where $d$ is the initial distance between the two planets of mass $m_1$ and $m_2$ and $G$ is the Gravitational constant. This gives a time of about $10^{23}$ years, much much longer than the universe has existed. This assumes Newtonian mechanics. Relativity would not change the conclusion much.
There is no known upper limit to gravity, and plenty of indirect evidence that it has no upper limit.
edited Feb 28 at 8:21
uhoh
6,95022172
answered Feb 9 at 12:36
James KJames K
34.8k257119
edited Feb 28 at 8:21
uhoh
6,95022172
edited Feb 28 at 8:21
uhoh
6,95022172
edited Feb 28 at 8:21
uhoh
6,95022172
6,95022172
answered Feb 9 at 12:36
James KJames K
34.8k257119
answered Feb 9 at 12:36
James KJames K
34.8k257119
answered Feb 9 at 12:36
James KJames K
34.8k257119
34.8k257119
2
$begingroup$
The collision speed of a test particle falling to Earth from infinity is equal to the escape velocity, about 11 km/s. For 2 Earth-mass bodies, the speed will be similar, I think you can just multiply it by $sqrt 2$, but I'm too sleepy to do the algebra right now. ;)
$endgroup$
– PM 2Ring
Feb 9 at 20:16
$begingroup$
What (indirect) evidence is available that gravity still acts 5 billion light years away?
$endgroup$
– Martijn Weterings
Feb 12 at 21:39
$begingroup$
I just did the algebra. The relative collision speed of 2 Earths is identical to the terminal speed of a test particle, so 11.186 km/s.
$endgroup$
– PM 2Ring
Feb 13 at 21:05
$begingroup$
"long time for them to collide" they'll only collide certainly if they are both "stationary" to begin with, or, have certain relative vectors. if they are moving to begin with, they'll be attracted but in many cases will end up in a (huge, mammoth) orbit around each other.
$endgroup$
– Fattie
Feb 15 at 11:38
$begingroup$
There is still the problem that there is indeed an effective upper limit to gravity. If two objects are too far apart, due to expansion their separation will increase faster than the speed of light. There are parts of the universe that will never experience gravity or light from other parts of the universe. See this answer and answers to Am I attracting Pluto?
$endgroup$
– uhoh
Feb 28 at 8:33
add a comment |
2
$begingroup$
The collision speed of a test particle falling to Earth from infinity is equal to the escape velocity, about 11 km/s. For 2 Earth-mass bodies, the speed will be similar, I think you can just multiply it by $sqrt 2$, but I'm too sleepy to do the algebra right now. ;)
$endgroup$
– PM 2Ring
Feb 9 at 20:16
$begingroup$
What (indirect) evidence is available that gravity still acts 5 billion light years away?
$endgroup$
– Martijn Weterings
Feb 12 at 21:39
$begingroup$
I just did the algebra. The relative collision speed of 2 Earths is identical to the terminal speed of a test particle, so 11.186 km/s.
$endgroup$
– PM 2Ring
Feb 13 at 21:05
$begingroup$
"long time for them to collide" they'll only collide certainly if they are both "stationary" to begin with, or, have certain relative vectors. if they are moving to begin with, they'll be attracted but in many cases will end up in a (huge, mammoth) orbit around each other.
$endgroup$
– Fattie
Feb 15 at 11:38
$begingroup$
There is still the problem that there is indeed an effective upper limit to gravity. If two objects are too far apart, due to expansion their separation will increase faster than the speed of light. There are parts of the universe that will never experience gravity or light from other parts of the universe. See this answer and answers to Am I attracting Pluto?
$endgroup$
– uhoh
Feb 28 at 8:33
2
2
$begingroup$
The collision speed of a test particle falling to Earth from infinity is equal to the escape velocity, about 11 km/s. For 2 Earth-mass bodies, the speed will be similar, I think you can just multiply it by $sqrt 2$, but I'm too sleepy to do the algebra right now. ;)
$endgroup$
– PM 2Ring
Feb 9 at 20:16
$begingroup$
The collision speed of a test particle falling to Earth from infinity is equal to the escape velocity, about 11 km/s. For 2 Earth-mass bodies, the speed will be similar, I think you can just multiply it by $sqrt 2$, but I'm too sleepy to do the algebra right now. ;)
$endgroup$
– PM 2Ring
Feb 9 at 20:16
$begingroup$
What (indirect) evidence is available that gravity still acts 5 billion light years away?
$endgroup$
– Martijn Weterings
Feb 12 at 21:39
$begingroup$
What (indirect) evidence is available that gravity still acts 5 billion light years away?
$endgroup$
– Martijn Weterings
Feb 12 at 21:39
$begingroup$
I just did the algebra. The relative collision speed of 2 Earths is identical to the terminal speed of a test particle, so 11.186 km/s.
$endgroup$
– PM 2Ring
Feb 13 at 21:05
$begingroup$
I just did the algebra. The relative collision speed of 2 Earths is identical to the terminal speed of a test particle, so 11.186 km/s.
$endgroup$
– PM 2Ring
Feb 13 at 21:05
$begingroup$
"long time for them to collide" they'll only collide certainly if they are both "stationary" to begin with, or, have certain relative vectors. if they are moving to begin with, they'll be attracted but in many cases will end up in a (huge, mammoth) orbit around each other.
$endgroup$
– Fattie
Feb 15 at 11:38
$begingroup$
"long time for them to collide" they'll only collide certainly if they are both "stationary" to begin with, or, have certain relative vectors. if they are moving to begin with, they'll be attracted but in many cases will end up in a (huge, mammoth) orbit around each other.
$endgroup$
– Fattie
Feb 15 at 11:38
$begingroup$
There is still the problem that there is indeed an effective upper limit to gravity. If two objects are too far apart, due to expansion their separation will increase faster than the speed of light. There are parts of the universe that will never experience gravity or light from other parts of the universe. See this answer and answers to Am I attracting Pluto?
$endgroup$
– uhoh
Feb 28 at 8:33
$begingroup$
There is still the problem that there is indeed an effective upper limit to gravity. If two objects are too far apart, due to expansion their separation will increase faster than the speed of light. There are parts of the universe that will never experience gravity or light from other parts of the universe. See this answer and answers to Am I attracting Pluto?
$endgroup$
– uhoh
Feb 28 at 8:33
add a comment |
$begingroup$
Yes: Given that the universe isn't expanding at a faster rate than the speed of the gravity effect of those objects, then the gravity effect of them would be able to reach one another.
Even then it would take a very long time for the gravity effects of the objects to reach one another, so the objects would just stay there motionless for ages(in this case 5 billion light years) before starting to move towards eachother.
http://www.nowykurier.com/toys/gravity/gravity.html
answered Feb 9 at 20:22
NoobNoob
113
$endgroup$
1
$begingroup$
The last part isn't ok.At least not in general. See for instance researchgate.net/publication/…. Anyway the Q is edited and a static universe is now specified. So the problem is reduced to test masset at infinity or whatever distance so the answer should be easier
$endgroup$
– Alchimista
Feb 10 at 9:01
add a comment |
$begingroup$
Yes: Given that the universe isn't expanding at a faster rate than the speed of the gravity effect of those objects, then the gravity effect of them would be able to reach one another.
Even then it would take a very long time for the gravity effects of the objects to reach one another, so the objects would just stay there motionless for ages(in this case 5 billion light years) before starting to move towards eachother.
http://www.nowykurier.com/toys/gravity/gravity.html
answered Feb 9 at 20:22
NoobNoob
113
$endgroup$
1
$begingroup$
The last part isn't ok.At least not in general. See for instance researchgate.net/publication/…. Anyway the Q is edited and a static universe is now specified. So the problem is reduced to test masset at infinity or whatever distance so the answer should be easier
$endgroup$
– Alchimista
Feb 10 at 9:01
add a comment |
$begingroup$
Yes: Given that the universe isn't expanding at a faster rate than the speed of the gravity effect of those objects, then the gravity effect of them would be able to reach one another.
Even then it would take a very long time for the gravity effects of the objects to reach one another, so the objects would just stay there motionless for ages(in this case 5 billion light years) before starting to move towards eachother.
http://www.nowykurier.com/toys/gravity/gravity.html
answered Feb 9 at 20:22
NoobNoob
113
$endgroup$
Yes: Given that the universe isn't expanding at a faster rate than the speed of the gravity effect of those objects, then the gravity effect of them would be able to reach one another.
Even then it would take a very long time for the gravity effects of the objects to reach one another, so the objects would just stay there motionless for ages(in this case 5 billion light years) before starting to move towards eachother.
http://www.nowykurier.com/toys/gravity/gravity.html
answered Feb 9 at 20:22
NoobNoob
113
edited Feb 10 at 18:45
answered Feb 9 at 20:22
NoobNoob
113
answered Feb 9 at 20:22
NoobNoob
113
answered Feb 9 at 20:22
NoobNoob
113
113
1
$begingroup$
The last part isn't ok.At least not in general. See for instance researchgate.net/publication/…. Anyway the Q is edited and a static universe is now specified. So the problem is reduced to test masset at infinity or whatever distance so the answer should be easier
$endgroup$
– Alchimista
Feb 10 at 9:01
add a comment |
1
$begingroup$
The last part isn't ok.At least not in general. See for instance researchgate.net/publication/…. Anyway the Q is edited and a static universe is now specified. So the problem is reduced to test masset at infinity or whatever distance so the answer should be easier
$endgroup$
– Alchimista
Feb 10 at 9:01
1
1
$begingroup$
The last part isn't ok.At least not in general. See for instance researchgate.net/publication/…. Anyway the Q is edited and a static universe is now specified. So the problem is reduced to test masset at infinity or whatever distance so the answer should be easier
$endgroup$
– Alchimista
Feb 10 at 9:01
$begingroup$
The last part isn't ok.At least not in general. See for instance researchgate.net/publication/…. Anyway the Q is edited and a static universe is now specified. So the problem is reduced to test masset at infinity or whatever distance so the answer should be easier
$endgroup$
– Alchimista
Feb 10 at 9:01
add a comment |
$begingroup$
YES!
Gravity will eventually pull them together.
The thing is that gravity exerts itself over very vast distances, although the force decreases exponentially over distance. BUT, two motion less massive objects will attract each other, without any other influence whatsoever.
answered Feb 13 at 5:30
Khawar Ali SherKhawar Ali Sher
62
$endgroup$
3
$begingroup$
"Exponentially" in a casual day to day sense but not in a mathematical sense. Gravitational attraction decays more quickly than inverse linear, doubling the distance more than halves the attraction, but not as fast as exponential. In is inverse quadratic which, in the world of maths, is slow compared to exponential.
$endgroup$
– badjohn
Feb 15 at 9:08
add a comment |
$begingroup$
YES!
Gravity will eventually pull them together.
The thing is that gravity exerts itself over very vast distances, although the force decreases exponentially over distance. BUT, two motion less massive objects will attract each other, without any other influence whatsoever.
answered Feb 13 at 5:30
Khawar Ali SherKhawar Ali Sher
62
$endgroup$
3
$begingroup$
"Exponentially" in a casual day to day sense but not in a mathematical sense. Gravitational attraction decays more quickly than inverse linear, doubling the distance more than halves the attraction, but not as fast as exponential. In is inverse quadratic which, in the world of maths, is slow compared to exponential.
$endgroup$
– badjohn
Feb 15 at 9:08
add a comment |
$begingroup$
YES!
Gravity will eventually pull them together.
The thing is that gravity exerts itself over very vast distances, although the force decreases exponentially over distance. BUT, two motion less massive objects will attract each other, without any other influence whatsoever.
answered Feb 13 at 5:30
Khawar Ali SherKhawar Ali Sher
62
$endgroup$
YES!
Gravity will eventually pull them together.
The thing is that gravity exerts itself over very vast distances, although the force decreases exponentially over distance. BUT, two motion less massive objects will attract each other, without any other influence whatsoever.
answered Feb 13 at 5:30
Khawar Ali SherKhawar Ali Sher
62
answered Feb 13 at 5:30
Khawar Ali SherKhawar Ali Sher
62
answered Feb 13 at 5:30
Khawar Ali SherKhawar Ali Sher
62
answered Feb 13 at 5:30
Khawar Ali SherKhawar Ali Sher
62
62
3
$begingroup$
"Exponentially" in a casual day to day sense but not in a mathematical sense. Gravitational attraction decays more quickly than inverse linear, doubling the distance more than halves the attraction, but not as fast as exponential. In is inverse quadratic which, in the world of maths, is slow compared to exponential.
$endgroup$
– badjohn
Feb 15 at 9:08
add a comment |
3
$begingroup$
"Exponentially" in a casual day to day sense but not in a mathematical sense. Gravitational attraction decays more quickly than inverse linear, doubling the distance more than halves the attraction, but not as fast as exponential. In is inverse quadratic which, in the world of maths, is slow compared to exponential.
$endgroup$
– badjohn
Feb 15 at 9:08
3
3
$begingroup$
"Exponentially" in a casual day to day sense but not in a mathematical sense. Gravitational attraction decays more quickly than inverse linear, doubling the distance more than halves the attraction, but not as fast as exponential. In is inverse quadratic which, in the world of maths, is slow compared to exponential.
$endgroup$
– badjohn
Feb 15 at 9:08
$begingroup$
"Exponentially" in a casual day to day sense but not in a mathematical sense. Gravitational attraction decays more quickly than inverse linear, doubling the distance more than halves the attraction, but not as fast as exponential. In is inverse quadratic which, in the world of maths, is slow compared to exponential.
$endgroup$
– badjohn
Feb 15 at 9:08
add a comment |
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1
$begingroup$
For a good 5 billions ly they ignore each other.
$endgroup$
– Alchimista
Feb 9 at 12:34
$begingroup$
I want to say that probably you consider the entire universe as to be the entire visible and/or observable universe. The accepted answer is indeed satisfactory only under several assumption. It is more to answer about two generic masses in a static enormous room. Else cosmology sets in
$endgroup$
– Alchimista
Feb 9 at 12:54
$begingroup$
I am familiar with the differences, but for this question to work i needed to be sure there where no outside factors affecting the two planets.
$endgroup$
– Tom
Feb 9 at 13:24
2
$begingroup$
Is the universe expanding?
$endgroup$
– userLTK
Feb 9 at 15:05
1
$begingroup$
Surely this is more of a physics question?
$endgroup$
– Fattie
Feb 12 at 14:50