Orbital effect of a sudden change to G

In summary, the conversation discusses the idea of changing the gravitational constant and its potential effects on the Earth's orbital radius. However, it is stated that it is impossible to accurately predict what would happen under these circumstances because it goes against the laws of physics. Another scenario is presented involving an asteroid joining with the sun and its impact on the Earth's orbit, but it is noted that this scenario also goes against the laws of physics. Ultimately, the conversation concludes that it is not possible to accurately answer the question without following the laws of physics.
  • #1
enotstrebor
120
1
If the gravitational constant suddenly changed, would the Earth change its orbital radius r' such that the new G'M'/r'^2 equals todays GM/r^2. If not how?
 
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  • #2
There is no way to answer the question "if I dispense with the laws of physics, what do the laws of physics say will happen."
 
  • #3
Vanadium 50 said:
There is no way to answer the question "if I dispense with the laws of physics, what do the laws of physics say will happen."

Another version which I think does not dispense with the laws of physics.

An asteroid 1.0*10^-15 the mass of the sun's mass joins with the sun (giving the sun's new mass M'). The asteroid's path into the sun does not disturb the orbit of earth.
Considering only the effect of the suns mass change (I know there are other effects), is there an orbital radius change such that M'G/r'^2 is equal to the old M_sun/r^2. If not, no matter how negligible the effect, what is the gravitational effect of the mass change to Earth's orbit (e.g. change in P?).
 
  • #4
You can't have an asteroid magically have no gravitational pull on the Earth until it hits the sun, and then magically have it's gravity restarted. There is no way to answer the question "if I dispense with the laws of physics, what do the laws of physics say will happen."
 
  • #5


The orbital effect of a sudden change to the gravitational constant, G, would depend on the magnitude and direction of the change. If G were to increase, the Earth's orbital radius, r', would decrease in order to maintain the same GM/r^2 ratio as today. Similarly, if G were to decrease, the Earth's orbital radius would increase.

This is because the gravitational constant, along with the Earth's mass (M) and the distance from the Earth to the Sun (r), determines the strength of the gravitational force between the two bodies. The equation for this force is F = GMm/r^2, where m is the mass of the Earth. If G were to change, the force of gravity and therefore the Earth's orbital speed would also change, requiring a corresponding adjustment in orbital radius in order to maintain a stable orbit.

It is important to note that this calculation assumes a constant mass for the Earth. If the mass were to change, the orbital radius would also be affected. However, changes in the Earth's mass are unlikely to occur suddenly and would likely have a more gradual effect on the orbital radius.

In conclusion, a sudden change to the gravitational constant would lead to a corresponding change in the Earth's orbital radius in order to maintain the same GM/r^2 ratio. This highlights the delicate balance and precise conditions necessary for a stable orbit.
 

1. What is the orbital effect of a sudden change to G?

The orbital effect of a sudden change to G is the change in the gravitational force exerted by a celestial body, such as a planet or star, on an orbiting object. This change can alter the orbit of the object, affecting its speed, distance, and trajectory.

2. How does a sudden change to G affect the orbit of a planet?

If the value of G decreases, the planet's orbit will become more elliptical, meaning it will be less circular and more elongated. This can cause the planet to move closer to and farther away from the sun, resulting in a change in its orbital speed and duration.

3. Can a sudden change to G cause a planet to be ejected from its orbit?

Yes, a sudden change to G can potentially cause a planet to be ejected from its orbit if the change is significant enough. This is because the gravitational force determines the strength of the bond between a planet and its star, and a decrease in G can weaken this bond, allowing the planet to escape its orbit.

4. How do other factors, such as the mass of a planet, impact the orbital effect of a sudden change to G?

The mass of a planet does not directly impact the orbital effect of a sudden change to G. However, a planet with a larger mass will experience a greater change in its orbit due to the sudden change in G compared to a smaller planet.

5. Can the orbital effect of a sudden change to G be reversed?

Yes, in theory, the orbital effect of a sudden change to G can be reversed if G returns to its original value. However, this would require a major shift in the laws of physics and is currently not possible with our current understanding of the universe.

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