Table of Contents
THE RISE & FALL OF NEWTONIAN GRAVITY:
The International Year Of Light - The Einstein Centenary 2015:
In 1915, the theory of General Relativity developed by Einstein showed how light was at the centre of the very structure of space and time 1).
A History Of Gravity:
It is more than three hundred years since Sir Isaac Newton wrote that although he had devised a mathematical system to describe gravitational effects, he had no idea how gravity worked:
As it is difficult to conduct a discussion about something that nobody understands, a fictitious 'force' of 'gravitational pull/attraction' was introduced as an explanation for gravitational effects.
Since then, there has been a revolution in both the maths and the understanding of how gravity works. Modern theory makes the notion of an attractive force redundant, but many of the old ideas remain entrenched, even in the headlines of the current Australian K-10 curriculum.
Excerpt - 2015 Australian Year 7 Curriculum (ACSSU118):
"Earth’s gravity pulls objects towards the centre of the Earth"
In the scientific community today, there is overwhelming agreement:
The concept of a gravitational 'force' that 'pulls' or 'attracts', is not correct.
Gravity is better understood to be a consequence of the curvature of 'space-time' rather than an 'attractive force'.
Video 1. Introduction to modern concepts about gravity & relativity
- IF UNABLE TO ACCESS YOUTUBE VIDEO (requires Flash) TRY:Relativity
Although we use many terms informally in day-to-day speech, we no longer believe (for example) that a cat really does have 'nine lives'.
Similarly, the idea that objects are 'attracted' to each other or 'pulled together' by 'gravity' has been rendered redundant and superseded by modern theory (see Video 1.).
For more than one hundred years, the idea that gravity 'pulls' or 'attracts' objects, has been rendered redundant.
A mountain stream is not really 'attracted' or 'pulled' to an ocean. The Moon is not really 'attracted' or 'pulled' to the Earth.
Both simply travel the path of least resistance. Source: Anon
At the PrimaryConnections site the DEC recommended core study resource for 'How Gravity Works' states: “Einstein didn't believe gravity was a force at all; he said it was a distortion in the shape of space-time”.
By ignoring this, we are trading a theory of gravity that physicists describe 'beautiful. simple and profound' for an old bowl of 'mystery meat'.
Why does this matter:
Early in the 20th century, Newton's model of gravity was superseded by Einstein's Theory of General Relativity, where gravity is not understood in terms of 'force' or 'pull', but is instead seen as a natural result of the geometry/geodesics of 'space-time'.
'How can empty space – which is nothing – actually do something (like curve) and how can nothing affect something?'
Special Relativity provides an answer for this, whereas Newtonian Gravity provides only a mystery.
It may be true that General Relativity seems 'more difficult' to understand compared with Newtonian gravity but this is not sufficient reason to continue teaching it when aspects of the theory (including the maths) are known to be wrong.
Ironically, when students enter tertiary physics courses, most of their difficulties and misconceptions are a result of what they were taught in school!
Video 2. Schools continue to teach 'Flat Earth' science - Impossible?
- IF UNABLE TO ACCESS YOUTUBE VIDEO (requires Flash) TRY:Common Physics Misconceptions
In 1998 scientists also discovered that the universe is not only expanding but that its expansion is accelerating.
This finding created what was referred to as the “most profound problem” in physics: The finding completely contradicts the old (Newtonian) understanding of gravity, which implied that attraction between mass in the universe should slow down expansion (not speed it up).
This evidence combined with the evidence supporting General Relativity, should be sufficient to ensure that the teaching of General Relativity takes precedence for the teaching of gravity in schools.
Why much of what is taught today in schools about gravity is wrong:
In the absence of contrary evidence, most people seem to believe that their own 'common sense' understanding of gravity fits the facts perfectly adequately - much like the common-sense misconceptions about a 'flat earth' and daily 'sunrise':
We're now so used to the idea that the Earth spins – rather than the Sun moves across the sky – it's hard for us to realize what a shattering mental revolution that must have been.
After all, it seems obvious that the Earth is large and motionless, the Sun small and mobile.
But it's worth recalling Wittgenstein's remark on the subject:
“Tell me,” he asked a friend, “why do people always say, it was natural for man to assume that the sun went round the earth rather than that the earth was rotating?”
His friend replied, “Well, obviously because it just looks as though the Sun is going round the Earth.”
Wittgenstein replied, “Well, what would it have looked like if it had looked as though the Earth was rotating?”
Source: https://www.ted.com/talks/richard_dawkins_on_our_queer_universe
For most day-to-day problems, the old mathematics is simple enough to teach and still works 'well enough'. Unfortunately, more sophisticated problems including just about everything related to modern technologies (such as GPS on our smart phones for example), the old maths and old understandings are so incorrect and inaccurate that they are useless.
A video link (and other resources related to modern theories about gravity) is included at the end of this page.
Video 3: Short, Introductory Comparison of Newtonian Gravity & General Relativity
- IF UNABLE TO ACCESS YOUTUBE VIDEO (requires Flash) TRY:Brian Green Introduces the Theory of General Relativity
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Old Versus New Gravity affects the answer two big question:
THE OLD QUESTION: If I stand on the ground and throw a ball up, why does the ball fall back down to the ground?
THE NEW QUESTION: If I stand on the ground and throw a ball up, why does the ball appear to fall back to the ground even though it MAY (depending on my frame of reference) keep going up forever?
Video 4. Why A Little Learning Is A Dangerous Thing:
- IF UNABLE TO ACCESS YOUTUBE VIDEO (requires Flash) TRY:Dunning Kruger Effect