# Can Gravity Cause an Object to Pull Itself Inward?

• James Gordon
In summary: I really needn't say more.In summary, the conversation discusses the concept of gravity and its relation to mass and inertia. It is mentioned that classical Newtonian mechanics is effective in understanding how gravity behaves, but understanding the current level of understanding of gravity and inertia requires knowledge of general relativity. Some people suggest that inertia is caused by interactions with the Higgs Field, but there is no solid evidence to support this theory. The conversation also touches on the importance of logic and evidence in scientific theories and the possibility of unknown factors in the laws of motion.
James Gordon
If gravity pulls things towards an object, is it possible that gravity pulls the object itself towards its own center, creating inertia?

James Gordon said:
If gravity pulls things towards an object, is it possible that gravity pulls the object itself towards its own center, creating inertia?

No.

Nugatory said:
No.

Is there a particular concept in physics that would help me to understand why?

James Gordon said:
Is there a particular concept in physics that would help me to understand why?

If you want to know how gravity behaves, classical Newtonian mechanics works well, and there are many excellent texts.

If you want to understand the current level of understanding of what gravity is and how it relates to mass and inertia, you'll have to spend some time learning what general relativity is about. There are s many bad pop-sci explanations out there that I'm reluctant to recommend a google search, but if you search through the relativity forum here you'll find some good answers (I particularly recommend member A.T.'s short video about an apple hanging on a branch and then falling) and also some good book recommendations.

Nugatory said:
If you want to know how gravity behaves, classical Newtonian mechanics works well, and there are many excellent texts.

If you want to understand the current level of understanding of what gravity is and how it relates to mass and inertia, you'll have to spend some time learning what general relativity is about. There are s many bad pop-sci explanations out there that I'm reluctant to recommend a google search, but if you search through the relativity forum here you'll find some good answers (I particularly recommend member A.T.'s short video about an apple hanging on a branch and then falling) and also some good book recommendations.

Thank you I will look into that.

Nugatory said:
If you want to know how gravity behaves, classical Newtonian mechanics works well, and there are many excellent texts.

If you want to understand the current level of understanding of what gravity is and how it relates to mass and inertia, you'll have to spend some time learning what general relativity is about. There are s many bad pop-sci explanations out there that I'm reluctant to recommend a google search, but if you search through the relativity forum here you'll find some good answers (I particularly recommend member A.T.'s short video about an apple hanging on a branch and then falling) and also some good book recommendations.

Some people argue that inertia is a result of particle interactions with the Higgs Field, which I thought was theorized after both Classical Mechanics and General Relativity. This does not seem to be in line with your response. Care to comment?

James Gordon said:
Care to comment?

Only if you can provide a pointer to a peer-reviewed paper instead of "some people say". As I mentioned above, there's a lot of really bad pop-sci out there.

Nugatory said:
Only if you can provide a pointer to a peer-reviewed paper instead of "some people say". As I mentioned above, there's a lot of really bad pop-sci out there.

Nugatory said:
Only if you can provide a pointer to a peer-reviewed paper instead of "some people say". As I mentioned above, there's a lot of really bad pop-sci out there.

Well, it seems as though the jury is out for many people on what is actually causing inertia. I certainly don't know for a fact what that is. I simply would like to be pointed out what is absolutely not possible about my question on the topic. If a person cannot do so succinctly I have to suspect that they do not know the answer themself, by which I do not mean as an offense, but rather an inescapable impartiality.

Nugatory said:
Only if you can provide a pointer to a peer-reviewed paper instead of "some people say". As I mentioned above, there's a lot of really bad pop-sci out there.

James Gordon said:
Well, it seems as though the jury is out for many people on what is actually causing inertia. I certainly don't know for a fact what that is. I simply would like to be pointed out what is absolutely not possible about my question on the topic. If a person cannot do so succinctly I have to suspect that they do not know the answer themself, by which I do not mean as an offense, but rather an inescapable impartiality.
1. It is personal speculation with no motivation, and no evidence.
2. It makes no quantitative predictions.
3. Nugatory summed the situation up adequately in post #2.

jbriggs444 said:
1. It is personal speculation with no motivation, and no evidence.
2. It makes no quantitative predictions.
3. Nugatory summed the situation up adequately in post #2.

jbriggs444 said:
1. It is personal speculation with no motivation, and no evidence.
2. It makes no quantitative predictions.
3. Nugatory summed the situation up adequately in post #2.

I agree with your first two points, and appreciate your response. Of course it is just a thought experiment of mine and not something I am pursuing professionally. From a logical perspective I have to disagree with your third point though. If a theory has no evidence, the possiblity of it being correct is not instantly no. At that state the possibility of its validity is within some area of the spectrum of uncertainy, unless there is some gross, known scientific error with the theory (which is really what my whole curiosity has been about given my relatively little amount of scientific schooling). Only when there is evidence that proves it is definitively untrue can you say it is not possible. Until then, blankly dismissing theories, regardless of their status, is not doing a service to science, IMO. I think as scientistists you must value logic before any other kind of directive or inclination. Currently our knowledge of the why or how of the 1st and 3rd laws of motion seems to be just sort of, 'it's that way because it is', which is really the sort of reasoning that is utilised by religions, not scientists. Scientists are supposed to be continuously searching for the reasons how and why. Thanks for your comments though. And thanks for being polite and civil.

J.G.

Your object persists in its state of rest or uniform motion in a straight line until acted upon by an external force - law of inertia. You are right, obviously, that the parts of the object are attracted to its centre of gravity, but that attraction cannot contribute to nor create inertia. Consider the moon, as Newton did. Every particle in the moon is attracted by the earth, but also tends to persist in "uniform motion in a straight line," the roughly circular orbit resulting. It is true that any particular lunar atom is attracted to the moon's centre, but that cannot affect the moon's inertia. Think of the lunar atom nearest to the Earth - does its acceleration towards the moon's centre cause resistance to the Earth's attraction? Well, obviously, since the moon doesn't (for a long while yet) rip apart. But there is a corresponding atom at the far point whose acceleration towards the centre adds to the acceleration towards the earth. Summed across the whole moon, there is no net resistance due to gravitational self attraction.

logico said:
J.G.

Your object persists in its state of rest or uniform motion in a straight line until acted upon by an external force - law of inertia. You are right, obviously, that the parts of the object are attracted to its centre of gravity, but that attraction cannot contribute to nor create inertia. Consider the moon, as Newton did. Every particle in the moon is attracted by the earth, but also tends to persist in "uniform motion in a straight line," the roughly circular orbit resulting. It is true that any particular lunar atom is attracted to the moon's centre, but that cannot affect the moon's inertia. Think of the lunar atom nearest to the Earth - does its acceleration towards the moon's centre cause resistance to the Earth's attraction? Well, obviously, since the moon doesn't (for a long while yet) rip apart. But there is a corresponding atom at the far point whose acceleration towards the centre adds to the acceleration towards the earth. Summed across the whole moon, there is no net resistance due to gravitational self attraction.

How is it that the moon's atom nearest the Earth accelerates toward the center of the moon when the atom is not actually moving in this sense? It is attracted to the center so to speak, but still locked in place for the most part. Myself I am not suggesting this concept you are referring to.

J.G.

Sorry - Principle of Equivalence.

logico said:
J.G.

Sorry - Principle of Equivalence.

No sorry required, friend!

## 1. What is gravity?

Gravity is a fundamental force of nature that causes objects with mass to be attracted to one another. It is responsible for keeping planets in orbit around the sun and for keeping us grounded on Earth.

## 2. How does gravity work?

Gravity works by the principle of mass attraction. The larger an object's mass, the greater its gravitational pull. This pull decreases as the distance between two objects increases.

## 3. What is the difference between gravity and inertia?

Gravity and inertia are both related to the movement of objects, but they are different concepts. Gravity is the force that pulls objects towards each other, while inertia is the tendency of an object to resist changes in its motion.

## 4. How does gravity affect the human body?

Gravity affects the human body in many ways. It keeps us on the ground, allows us to walk and run, and helps us maintain balance. In space, where there is less gravity, astronauts experience changes in their body, such as bone and muscle loss.

## 5. Can gravity and inertia be manipulated?

Yes, gravity and inertia can be manipulated through various means. For example, astronauts experience weightlessness in space because there is less gravity. Inertia can also be manipulated through external forces, such as a rocket's thrust, to change an object's direction or speed.

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