why did einstein say that newtons laws of motion were wrong on a macroscopic scale?

Question

why did einstein say that newtons laws of motion were wrong on a macroscopic scale?

Answer 1

There were emerging many cases where Newton's Gravity were failing to give the right answer to observations. Newton viewed gravity as a force of nature, Einstein changed that view to gravity being a curve of nature instead. Einstein's view is that gravity isn't really a force, it's a curvature of space, which fools us into believing that it's a force, so really it's a pseudo force.



It's not to say that Newton's gravity is completely wrong, it is special case that works for the most part only in the environment that we're in, namely on Earth. It also works very well, for the most part in the environment of space, maybe 95% of the time, but the remaining 5% of the time requires the more complex equations of Einstein's Relativity. One famous example of where Newton's gravity failed utterly was in calculating the orbit of Mercury. Mercury is so close to the high gravity of the Sun that Newton's laws become only an estimate. And the estimate starts giving slightly wrong answers very quickly, which starts to add up over the years.



Another famous case where Newton's laws were wrong were not too far from Earth either, right in Earth orbit, where the GPS satellites live. If we didn't use Einstein's laws rather than Newton's laws, GPS would never work right. The navigational data would start to drift off by 10 km per day or something like that! So even on Earth it's noticeable in special cases.

Answer 2

He couldn't stand the thought that a guy with an IQ of 200 could out think him with only a 160 IQ. Really?



Newton was not wrong. He was absolutely correct for the assumptions he made. In fact way more people (e.g., NASA) use Newton's gravity equations than Einstein's.



If a model produces the desired results when using it under the proper conditions, that model is not wrong. It might be different from other models, but it's not wrong.

Answer 3

Every theory has its useful zone, and its limits.

The best theories have the biggest, fattest, widest useful zones, and Newton's Law of Universal Gravitation (NLG) is one of those. But even that theory has limits; what Einstein did, was to find them.



He was able to accomplish that after formulating the Theory of Special Relativity (SR) in 1905, one of the consequences of which was that no signal can travel faster than c.



But according to NLG, if the masses in one place are rearranged, any mass in another place, no matter how remote, must instantaneously change the nature of its motion to respond to the new arrangement. That is inconsistent with SR, and Einstein spent 10 years developing a new framework for a new theory of gravity; the theory of General Relativity (GR), published in 1915.



But one of the essential features he required before he could release GR to the world, was that it reduce to agreement with NLG for that theory's useful zone. Namely, whenever all velocities are well below c, and every concentration of mass, M, is of a size that that is much larger than its Schwarzschild radius:



R₀ = 2GM/c²



No situations violating these limits had ever been encountered, so NLG was successful for all the systems it could be tested for.

But that also depends on how accurately you can observe things, and for how long a time. And there were some small discrepancies — the motion of Uranus was found to deviate slightly from predictions, and one proposed resolution was an 8th planet. It was predicted and in 1846, Neptune was discovered.

But then after some years, Neptune's mass was found not to account fully for the discrepancies in Uranus' motion, and a 9th planet was predicted, and a search for it begun.

What was found, Pluto, wasn't enough to cover the discrepancies; until more calculations were done, and those discrepancies evaporated; all was explained by NLG.



Another problem for NLG was Mercury's orbital precession — its line of nodes, the aphelion-perihelion line, slowly revolved. Most of that precession IS predicted by NLG, due to the Sun's oblateness, the influences of other planets, etc., but there was this tiny but definite residual precession that wasn't.

Einstein's GR successfully explained that. As well as the gravitational deflection of starlight by the Sun, as measured during the solar eclipse of 1919.



And while there have been many more tests of GR in the century since its birth, it still has known limits. It's well known to conflict with quantum mechanics, but this delves into situations that are still unattainable for testing.



EDIT:

Or maybe you were referring to Newton's 3 Laws of Motion (NLM) — another theory with perhaps an even wider useful zone.

In the late 19th century, it came into conflict with electromagnetism; specifically, James Clerk Maxwell's electromagnetic field equations, which predict electromagnetic waves that always move with speed c, regardless of the motion of source or observer.

Einstein reconciled the two with his SR theory, by combining space and time into a single, 4-D geometric object.



NLM hold when speeds are all much slower than c. And once again, SR reduces to NLM in those cases.