Register to reply

Gravity a pushing force?

by jkg0
Tags: force, gravity
Share this thread:
jkg0
#1
May4-14, 05:13 PM
P: 11
I've always thought about gravity as a pulling force but perhaps it isn't. Is there anything fundamentally wrong with thinking about gravity as a pushing force attenuated by matter?
Phys.Org News Partner Physics news on Phys.org
First in-situ images of void collapse in explosives
The first supercomputer simulations of 'spin?orbit' forces between neutrons and protons in an atomic nucleus
Magnets for fusion energy: A revolutionary manufacturing method developed
ZapperZ
#2
May4-14, 06:14 PM
Emeritus
Sci Advisor
PF Gold
ZapperZ's Avatar
P: 29,239
Physics isn't just "what comes up must come down". Physics must also say when and where it comes down.

When you are considering something like this, you simply cannot do it via hand waving argument. You need to produce accurate, mathematical description that matches all our current observations on gravity. It is only after you can present that will something like this be considered and taken seriously. Otherwise, you will be another one of the people who come here with some vague idea and wanting the rest of us to do the dirty work of falsifying something that is half baked. This is not something we do in this forum, because there are in infinite number of such scenarios that anyone can come up with.

Zz.
Bandersnatch
#3
May4-14, 06:15 PM
P: 688
Have you read this?
http://en.wikipedia.org/wiki/Le_Sage...of_gravitation
Especially the predictions bit.

Chestermiller
#4
May4-14, 06:58 PM
Sci Advisor
HW Helper
Thanks ∞
PF Gold
Chestermiller's Avatar
P: 5,050
Gravity a pushing force?

Quote Quote by jkg0 View Post
I've always thought about gravity as a pulling force but perhaps it isn't. Is there anything fundamentally wrong with thinking about gravity as a pushing force attenuated by matter?
Are you referring to what Michio Kaku said in the TV documentary on Einstein?

Chet
Matterwave
#5
May4-14, 07:03 PM
Sci Advisor
Matterwave's Avatar
P: 2,663
Quote Quote by Chestermiller View Post
Are you referring to what Michio Kaku said in the TV documentary on Einstein?

Chet
When Michio Kaku made that statement... my mind exploded...
dauto
#6
May4-14, 08:10 PM
Thanks
P: 1,948
Quote Quote by Chestermiller View Post
Are you referring to what Michio Kaku said in the TV documentary on Einstein?

Chet
What was his comment?
Chestermiller
#7
May4-14, 08:31 PM
Sci Advisor
HW Helper
Thanks ∞
PF Gold
Chestermiller's Avatar
P: 5,050
Quote Quote by dauto View Post
What was his comment?
Believe it or not, he said that gravity doesn't pull you. The relativistic explanation of gravity is that it pushes you. Here is a link to the documentary, now available from youtube:

http://www.youtube.com/watch?v=KcXxHZssCh4

This is one of the shows that got me interested in studying Relativity. I wanted to find out whether what they were saying was correct or not. In this case, Yiiiiiiiiiii!!!!!!

I don't know how he could say something like this in a medium where it would be preserved forever for people to see.

Chet
A.T.
#8
May5-14, 06:23 AM
P: 3,908
Quote Quote by dauto View Post
What was his comment?
He talks about "space pushing" objects towards the mass after 2:00:



I guess it is his way to describe inertia: As an interaction with space, which opposes deviations from free fall. Not my favorite way to put it.
Chestermiller
#9
May5-14, 07:05 AM
Sci Advisor
HW Helper
Thanks ∞
PF Gold
Chestermiller's Avatar
P: 5,050
Yes. He also mis-states in no uncertain terms that Special Relativity does not apply to accelerating objects. Many of the things said in this video are a PF "worst nightmare."

On the other hand, I love this video because of the historical perspective and the personal stories, including Einstein's "soap opera" personal life, his relationship to Planck and Haber, and the stories about the attempts to prove GR using solar eclipses.

Chet
dauto
#10
May5-14, 10:20 AM
Thanks
P: 1,948
Man, that was a terrible video. Why do they even try...
Jano L.
#11
May6-14, 01:53 PM
PF Gold
P: 1,146
The story about push seemed strange to me too at first. There is this curved 2D surface which pushes the marble to make it move in circles. Perhaps they just wanted to communicate the idea that gravity in Einstein's theory is similar to the curved surface. Instead of "curvature determines the trajectory" they said gravity pushes the body to make it similar to the curved surface where the marble indeed moves in circles due to push (contact forces of constraint cannot pull)...

...I rather would not be too harsh on them. This is probably close to where one can go without using mathematics...
A.T.
#12
May6-14, 02:26 PM
P: 3,908
Quote Quote by Jano L. View Post
There is this curved 2D surface which pushes the marble to make it move in circles.
That is an even worse analogy. Discussed many time here.
http://www.physicsforums.com/showthr...21#post4597121

Quote Quote by Jano L. View Post
This is probably close to where one can go without using mathematics...
One can do much better without using mathematics:



http://www.physics.ucla.edu/demoweb/...spacetime.html
http://www.relativitet.se/spacetime1.html
http://www.adamtoons.de/physics/gravitation.swf


Register to reply

Related Discussions
Gravity as a pushing (i.e., not pulling) force? Quantum Physics 1
Kinetic Friction, Undefined Pushing Force, Find Normal Force. Introductory Physics Homework 4
Work (done by gravity) - pushing up a ramp Introductory Physics Homework 12
Is pushing considered a force? Introductory Physics Homework 11
Force when 2 blocks pushing against each other Introductory Physics Homework 4