Was Newton wrong about gravity?

Question

The statement saying a black holes Gravity is so strong that even light cant escape would not represent Newtons findings.I seem to remember from high school that newton said gravity is a force that exists between objects with Mass.So my question has to be,since a photon has no mass how would gravity Directly influence the behavior of a photon?May the light shine on me.

Answer 1

Newton described how gravity worked very well, but he ignored what it was. Newton had no way to know about the speed of light as a cosmic constant or the warping of spacetime.



Photons by definition follow the shortest path (a geodesic). Einstein said that photons follow a curved path because the follow the curvature of spacetime, not because they are attracted by gravity.



Photons moving away from a black hole are moving "up" an energy gradient of curved spacetime. By Conservation of Energy, photons must lose energy as they move "up." Since they cannot slow down the only choice is to increase in wavelength (red shift). The photons lose more and more energy until it is all gone and they disappear.





We have 2 equally good theories for what gravity is:



General Relativity: Gravity is mass warping the fabric of Space-Time



Quantum Mechanics: Gravity is the exchange of “Messenger Particles” called gravitons. It works like a game that combines Simon Says with Catch. The players (masses) throw balls (gravitons) to each other. Every time a player catches a graviton, if the player is free to move, the player moves one step closer AND adds a graviton to the number in play.



General Relativity: Another thought experiment: Einstein thought, "What exactly is gravity?" Newton described how gravity worked but could not figure out what it was. Example: The earth is attracted to the sun. But, how does the Sun do that? Where is the "rope" that allows the sun to pull on the earth? Newton ignored the question.



Einstein tackled it. And thought (My paraphrase): Suppose you were captured by aliens and drugged, you wake up in a sealed room. The room could be sitting motionless on the earth or you could be on the alien’s spaceship being taken back to their home planet. The space ship could have a soundless, vibration less rocket motor that we cannot tell if it is firing or not. If it is firing it is accelerating the room at 9.8 m/s^2 Is there any experiment that we can do that will allow you to figure out if the room is sitting motionless on the earth or accelerating through space at 9.8 m/s^2? Turns out there are no way to figure out if we are sitting on earth or accelerating through space. This means: If we cannot tell the difference, then there is no difference. ===> Gravity is not a force but acceleration that manifests itself as a warping (curving) of Space-Time. (A very profound conclusion. Newton caught a whiff of this insight, but missed its’ significant. F = MA To get a Force you multiply Mass times Acceleration).

Another way to say this: Masses are not attracted to each other, they just follow the curvature of space-time. The acceleration of gravity is the slope of the curvature of space-time.



Einstein knew from Special Relativity that acceleration would warp Time and Space ===> Gravity is mass warping Time and Space (Space-Time) ===> General Relativity



The warping of Space-Time is necessary for General Relativity. Einstein's reasoning requires it. If it was a force as Newton proposed, then if the mass of the sun disappeared the earth instantly leave its orbit. But, Special Relativity says that nothing, not even gravity can travel faster than light ====> It must take about 8 minutes for the earth to leave its orbit after the sun disappeared. With GR there would be a "ripple" in the fabric of Space-Time that when calculated actually moves at c. All this would be conjecture except we can test GR and its predictions are accurate

Very nice graphic of the Gravity Ripple at:



http://www.pbs.org/wgbh/nova/elegant/program.html

1st Hour – A New View of Gravity



The "proofs" are down in Section 4



http://en.wikipedia.org/wiki/Introductio…



If Quantum Mechanics is correct and Gravitons exist, the answer to the original question remains the same: Gravitons travel at the speed of light ===> Still takes 8 minutes. But what is gravity? An acceleration due to the warp in Space-Time or a force "carried" by a Messenger Particle? The Graviton (if it exists) would be the "rope" linking the sun to the earth..====> The result of the Thought Experiment changes: We can now tell the difference because we can in theory detect Gravitons and tell if we are under gravity or acceleration. OPINION: Gravitons are NOT a foregone conclusion. Gravity is so different from the other 3 Fundamental Forces, its mechanism could easily be different. It will be interesting to see how it shakes out. For now: Opinion - Gravity is an acceleration that results from the warp of Space-Time.

Answer 2

1

Answer 3

General relativity predicts that light will bend in space as a result of gravity. It is called gravitational lensing. As the gravity increases the more it bends. The gravity can reach a critical point where the light becomes "stuck". I don't want to over simplify it.

Just bear in mind that Newton's theories make accurate predictions in most situations but not when things become extreme (very high masses, speeds, distances).

I recommend reading some pop culture science books and comfortable maths books so you can have an image ready for when you reach the level of maths understanding necessary a few years down the line.

Answer 4

Newton was not completely right about gravity. Einstein gave us a replacement theory called General Relativity that does explain such things as black holes, while also explaining the things Newton's gravitational theory explains.



Another discrepancy in Newton's theory was the orbit of Mercury. By the 1850s, astronomers had figured out that there was a tiny discrepancy, a few arc seconds per century, between the theoretical and actual motion of Mercury's orbit. They thought this was due to an extra planet closer to the sun than Mercury, but the answer turned out to be that Newton's theory was just slightly off in a gravitational field that strong (Mercury is very close to the sun).



So Newton's theory is "wrong" in the sense of being off by infinitesimal amounts close to the sun, or in how light is affected by gravity. But it's still more than accurate enough to compute the motions of bodies in the solar system for centuries at a time, and it's mathematically very simple. So we still use it.

Answer 5

Newtonian gravitation and general relativity have very different ways of looking at gravity. Both work in the environments in which we live. Newtonian gravitation breaks down in the realm of high gravitational fields.



In Newtonian physics, gravity is the attraction of two masses. In general relativity, a mass creates a gravity well in spacetime. (One GR adage is, space tells mass how to move, mass tells space how to warp.) For a black hole, the gravity well is such that the escape velocity is greater than the speed of light for anything inside the event horizon, so light can't escape, even though it's not "attracted" in the Newtonian sense.



Note, quantum theory doesn't have anything to do with general relativity. General relativity is a classical theory that actually breaks down at the quantum scale. The proposed TOEs attempt to address gravitation at the quantum level. One of the features is that space is quantized, so nothing can get close enough together to cause the GR breakdowns.

Answer 6

Right and wrong are not terms that apply here.



Newton's theory on gravitation was correct for hundreds of years, because every test showed it was correct, and it could correctly predict the behavior of the universe.



And it still does, with a few exceptions. So Einstein's corrections are better than Newton's in prediction the the universe, since it does work as well as Newton's and also covers the exceptions.



But Newton's math still is used as it still works for just about all conditions we encounter.



Re black holes, those are hypothetical, we don't even know they actually exist, and if they do, what laws of physics apply.

Answer 7

Photons only have zero mass when they are at rest. Any photon that is in motion has a tiny mass - 1.7867745 x 10 -42 g. Newton was not wrong about gravity.

Answer 8

I personally think that there is no gravity as Newton said. I will show this as:

As we know the earth's velocity on the axis (Rotational velocity at the equator) is 465,1.00 m/s --> 1674,4.00km/hours ........ And the earth's velocityon orbit (cosmic speed level 1): 29,783.00 km/sec -->107,218.00 km/hour; Cosmic speed level 2:11,186.00km/s --> 40,269,600.00/h ( checking at wiki).

So with the very fast speed which the wiki show us, we can decuce that everything on the earth including people can walk and stand one point on the earth is 3 kinds of speed above and speed of the other planets around the earth.

.

If we have chance, we do a sample solar, we can easily understand.



I'm very sorry my English is not enough in this Physics, so I can not describe more but I think, if we think about what I have just said, everything is clear.



Thanks for your reading

Answer 9

Newton discovered gravity and it still works and is used for classical systems. Sure, Einstein built up upon it through the theory of relativity but it still does not discredit Newton at the very least. If anything, he was the largest contributor to the foundations of real physics stuff. Newton owns Einstein in my book.

Peace.



Don't bother rating me my friend :). I'm just doing my (religious) duty (islamic) towards mankind to try and help them out at times of need.

Answer 10

Newtonian physics breaks down on the quantum scale, which is why when you start look at actual particles, you get into quantum mechanics.

Answer 11

Uniontera number 2, hope it helps. This is a reason of your so-called gravity.



Uniontera number 6-2, hope it helps. This is your so-called light.



Uniontera number 10, hope it helps. This is your so-called black hole.



Existence is the time expressed by light itself. http://www.youtube.com/watch?v=MjmOw1Pnc4s



1. When same times met ... Arrow A (This is your so-called "Energy". / Cause of Laser / Origin of Death / Reason of Chemical reaction)

2. When different times met ... Arrow B (This is your so-called "Mass". / Cause of Higgs boson / Origin of Life / Reason of Biological reaction / cf. Gravity)

3. The rose line is the beginning light. (result from Genesis 1:3)

4. The existence of different time. (result from relativity of light)

5. 2 dimension is not a space. (result from 2-axis, math)

6. Universe came from nothing. (result from No.5 / cf. Playing with bubbles)

6-1. A barrier[posititon] exist between the inner and outer bubbles. But universe do not have that barrier. (Cause of Inertia / Reason of Sun / Position of Antimatter / Origin of Fire / cf. Expansion, Conservation of parity, Time-reversal invariance)

6-2. Nothing is not a no existence. No existence is a zero dimension. There is two zero dimension. One has a position. The other doesn't have a position. These different positions were connected by something. That "something" is not a what but a way. (Cause of Light / cf. Ether)

7. Progress / Event / Probability is a time. (This is my trinity.)

8. Wave-particle duality of light, creation & evolution, uncertainty principle, etc. (result from No.7)

9. Coalescing of different times. (Cause of Rotation & Spin / Equator has plenty of time. / Origin of Colour / Reason of Reflection / cf. Strong interaction)

10. Your so-called "Black hole" is a wholly condensed time. (cf. Kerr spacetime)

11. The reason of your so-called "Magnetic field". (result from step3 and 4)

11-1. The reason of your so-called "Dark matter". (result from step3 to 4 / Energy-Mass duality / cf. Dark energy "step4 to 3")

12. The reason of your so-called "Electric field". (result from the crack of time / Same time's crack is a different time's connection. / Cause of Static electricity)

13. Your so-called "Space" is a crack of time. (result from No.12 / Cause of Lightning / Reason of Refraction / cf. Weak interaction)

13-1. The reason of your so-called "Capture & Decay". (result from No.13's crack of time / cf. Violation of time-reversal invariance)

13-2. The reason of No.6-2's "position & none position". (result from No13-1's "capture & decay")

13-3. The reason of No.13's space. (result from No.13-2's "position & none position" / cf. Noneconservation of parity)

14. Boundary is a crack of space. (result from No.13 / Same space's crack is a different time's contact. / Cause of Superfluid / cf. Fractal)

15. Boundary is nothing. Your so-called "Hole" is a boundary itself. Also, nothing is K=0 temperature. (result from No.14 / cf. Calabi-Yau, Hilbert space)

16. This is a wall of your so-called "Fire". (result from No.15) - copyright ⓒ uniontera



Our nonsense has come from one time. Uniontera is a key.



English is not my first language, sorry!



If it is difficult to understand, just remember & enjoy "Hand touching everything is a time". This is the only one result of uniontera.