If Gravity Isn`t a Force but Spacetime Geometry Property, why books consider it as a force?

[Nicholas Kang]

I am now studying in secondary school. Most of the time I have encountered classical physics, stating gravity is a force, time is constant, distance/displacement is constant, mass is constant, electrons orbit around the nucleus of atoms, etc. Anyone who study Modern Physics would immediately know that the above statements are wrong. If wrong(some may argue that it is just incomplete), then why continue to teach wrong ideas, and then only try and start to correct somebody when he/she is in university. But by the time he/she is in university, it is too late. The very firm idea that gravity is a force, time is constant, distance/displacement is constant, mass is constant, electrons orbit around the nucleus of atoms, etc is well and deeply established, anchored at the deepest realm in side the brain. Adapting a change may not be easy for some people. I used to argue with my teacher over modern/classical physics issues. If Modern Physics were to be taught in secondary school, then such arguments would be unnecessary. So why teach the wrong ideas, the misleading ideas, and somewhat force somebody to change their mind again in university. What`s the point of doing repeated jobs? Simply teach Modern Physics one-off would be better.

 

Please shed light on this issue. Thanks.

 

Serving the Scientific Community,

 

Nicholas Kang

[swansont]

Most people aren't going to go on and study physics in great depth, so fro them teaching things that are approximately true is as much depth as you need. You need a certain level of brain development to handle physics concepts as well as a background in basics concepts like energy. You can't get into relativity from the very start. You have to make sure that misconceptions that crop up in understanding classical physics have been cleared up.

[imatfaal]

1. There is no CORRECT explanation - there are merely a series of models that we use to predict and inform. Each model has areas of applicability - some are wide others are narrow; you choose which you wish to use dependent on your question.

 

2. Most everyday experiments that can be carried out in a school demonstration or scenarios we may encounter can be modelled very accurately using simple classical physics (there are exceptions) - so we teach classical physics first as that is of most immediate concern.

 

3. You have to be able to walk before you can run. The maths, the ability to deal with contradiction, the sheer complexity of some modern physics is not easily taught - thus it is only taught to those who have shown both an aptitude and a desire to learn physics.

[Nicholas Kang]

I can conclude that from both of your words, I am stupid enough to study Modern Physics from now. So, Should I stop studying (Modern Physics)?

2. Most everyday experiments that can be carried out in a school demonstration or scenarios we may encounter can be modelled very accurately using simple classical physics (there are exceptions) - so we teach classical physics first as that is of most immediate concern.

 

Examples of exceptions please. i just need to check and see whether your examples agree well with my speculations, though my brain is empty now.

[swansont]

I can conclude that from both of your words, I am stupid enough to study Modern Physics from now. So, Should I stop studying (Modern Physics)?

 

Learning modern physics is harder if you haven't developed an appreciation of the basic concepts that go into it.

[Nicholas Kang]

Do you think I have developed that appreciation of basic concepts? I can`t judge myself. And it would be crazy to manage a poll to collect feedback regarding this question, so the only way is to ask.

[studiot]

I'm glad imatfaal brought up the subject of models.

 

Not only are models valuable for on their own merit, they also form a basis for other theory used for other purposes, perhaps by engineers or applied scientists.

 

Inappropriately 'accurate' or elaborate models can even get in the way.

 

For instance golf balls move fast, but no one would apply the principle of relativity to their flight through the air.

 

However relativity mechanics is the only way to explain the flight of muons through the same atmosphere.

[Nicholas Kang]

For instance golf balls move fast, but no one would apply the principle of relativity to their flight through the air.

 

However relativity mechanics is the only way to explain the flight of muons through the same atmosphere.

 

What do you mean?

[harshgoel1975]

I am now studying in secondary school. Most of the time I have encountered classical physics, stating gravity is a force, time is constant, distance/displacement is constant, mass is constant, electrons orbit around the nucleus of atoms, etc. Anyone who study Modern Physics would immediately know that the above statements are wrong. If wrong(some may argue that it is just incomplete), then why continue to teach wrong ideas, and then only try and start to correct somebody when he/she is in university. But by the time he/she is in university, it is too late. The very firm idea that gravity is a force, time is constant, distance/displacement is constant, mass is constant, electrons orbit around the nucleus of atoms, etc is well and deeply established, anchored at the deepest realm in side the brain. Adapting a change may not be easy for some people. I used to argue with my teacher over modern/classical physics issues. If Modern Physics were to be taught in secondary school, then such arguments would be unnecessary. So why teach the wrong ideas, the misleading ideas, and somewhat force somebody to change their mind again in university. What`s the point of doing repeated jobs? Simply teach Modern Physics one-off would be better.

 

Please shed light on this issue. Thanks.

 

Serving the Scientific Community,

 

Nicholas Kang

 

I appreciate your concern... this is infect a good question....to build the complex concepts ... the simpler concept are used... and gradually as we graduates.. those become more deeper and complex and refined .... with the time... new observations are added and to explain them... existing model has to be enhanced refined or sometime redefined....this is ongoing process.....but many time most stable/accepted/agreed version is adopted for curriculum.....sometime time in the bottom corner or the appendix.. the latest update is provided ....it is a curve..... from observation to established law....that it take time.....nevertheless .truth is never distorted ( should not be at least ) but presented in such a way that it satisfy the given conditions....... Keep the Sprint high..

[Nicholas Kang]

Now, what should we teach first? Should we teach the correct but unfamiliar law with its strange and difficult conceptual ideas, for example the theory of relativity, four-dimensional space-time, and so on? Or should we first teach the simple “constant-mass” law, which is only approximate, but does not involve such difficult ideas? The first is more exciting, more wonderful, and more fun, but the second is easier to get at first, and is a first step to a real understanding of the first idea. This point arises again and again in teaching physics. At different times we shall have to resolve it in different ways, but at each stage it is worth learning what is now known, how accurate it is, how it fits into everything else, and how it may be changed when we learn more.

 

This is a short paragraph from Feynman`s Lectures of Physics, Volume 1, Chapter 1 Atoms in Motions. Now, I know why, again sorry for posting useless topics. In fact, this topic won`t had existed if I had read the online ebook now. Thanks for support. I will try to keep myself as near as possible to the edge of Modern Physics and at the same time understand classical physics deeply and have a firm foundation before I proceed to Modern Physics, as imatfaal`s words conclude, you have to be able to walk before you run. Yes, I got it. So, thanks.

Link: http://www.feynmanlectures.caltech.edu/I_01.html

See paragraph 8.

[studiot]

 

Or should we first teach the simple “constant-mass” law, which is only approximate

 

Is it?

 

A scientist on a rocket measures the mass of a test ball with him in the rocket.

The rocket then accelerates to nearly the speed of light.

The scientist performs the same experiment on the same ball in the rocket.

 

Does he measure any change of mass?

 

Compare with the muon experiment I referred to earlier

 

http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/muon.html

[Nicholas Kang]

You don`t trust Feynman? No, I don`t think so. You can refer to the link, it is a very short paragraph from a long article. I know the muon experiment. Because muon travels at the speed of light, so many of them experience time dilation, eventually they are able to survive at large amounts near the earth atmosphere. This experiment is mentioned in the book Einstein`s Relatively Simple by Ira Mark Egdall.

[studiot]

 

I know the muon experiment. Because muon travels at the speed of light, so many of them experience time dilation

 

No not exactly.

 

From the muon's point of view there is no time dilation (or mass increase).

The muon doesn't experience anything.

 

But from the point of view of an observer on Earth both occur.

[imatfaal]

 

No not exactly.

 

From the muon's point of view there is no time dilation (or mass increase).

The muon doesn't experience anything.

 

But from the point of view of an observer on Earth both occur.

 

Although the distance they need to travel through the atmosphere is contracted which accounts from the muons "point of view" why so many manage to make it through the atmosphere

...I know the muon experiment. Because muon travels at the speed of light, so many of them experience time dilation, eventually they are able to survive at large amounts near the earth atmosphere. ..

 

Muons are massive and thus cannot travel at the speed of light - the muons caused by cosmic rays impacting on the outer atmosphere are doing about .98c

Edited September 10, 2014 by imatfaal
clarification of muon heritage

[studiot]

Yes that is true, but the atmosphere is travelling relative to the muon's frame of reference.

Edited September 10, 2014 by studiot

[michel123456]

That is because the educational system is not only there to make you learn something but mainly to filtrate.

[ajb]

My own view is that we should consider gravity as a force; test particle experience acceleration and so we have a force. End of story...well not quite.

 

The distinction between a force and a pesudo-force in this context is subtle and technical. I don't think it is worth being too worried about this at this point. If you study mechanics and relativity at a sufficiently high level you probability won't be too worried the distinctions anyway. You know how to deal with gravitational fields and if you call if a force or a pesudo-force will not make any real difference.

 

We also know how Newtonian gravity fall out of general relativity and that Newtonian gravity is a good theory for a wide range of scales.

 

Thus, at school it makes sense to deal with Newtonian gravity first. It is much simpler to mathematically describe and gives good results for everyday phenomena. Only later will you need to worry about where it does not work so well.

[Nicholas Kang]

Only later will you need to worry about where it does not work so well.

 

Why worry about it later? Since one day you will have to worry about it, why not worry about it now and solve your problems in the future, so that instead of worrying in the future, you can study other related subjects even deeper but not wasting time to worry about such matters in the future.

 

And how do you explain the fact that most students have had their wrong(inaccurate) ideas anchored deep and firmly inside the brain, which means they face difficulities in university? Learning should be fun, shouldn`t it? But instead of learning happily, they have to struggle to change their mind, trying to cope with the correct(accurate) ideas, why doing things twice? Why making students continue to wander around the world full of inaccuracy and incomplete ideas?

That is because the educational system is not only there to make you learn something but mainly to filtrate.

 

In my opinion, you will learn how to filtrate when you learn something because this is one of the main reasons why you need to learn.

[ajb]

Why worry about it later?

You won't have the knowledge at high school to really discuss this. At the school level you have an acceleration of test particle and so a force. You would need to go into some details about coordinate systems and a little differential geometry to begin to understand the pseudo-force nature of gravity. For a lot of phenomena you can forget all this and just use Newtonian gravity which fits into the standard picture of statics and mechanics as presented at school.

 

And how do you explain the fact that most students have had their wrong(inaccurate) ideas anchored deep and firmly inside the brain, which means they face difficulities in university?

Is this really the case? I am not sure.

 

 

Learning should be fun, shouldn`t it?

Truthfully, it is not always fun but rather a lot of hard work.

[Nicholas Kang]

You won't have the knowledge at high school to really discuss this. At the school level you have an acceleration of test particle and so a force. You would need to go into some details about coordinate systems and a little differential geometry to begin to understand the pseudo-force nature of gravity. For a lot of phenomena you can forget all this and just use Newtonian gravity which fits into the standard picture of statics and mechanics as presented at school.

 

 

So, why not teaching some basic knowledge at high school?

 

Is this really the case? I am not sure.

 

 

Try asking your students or simply conduct a survey then you will know the truth. Remember that the whole classical physics of high school is being overturned by modern physics of university, except some basic fundamental concepts that persist ever since it is being taught.

 

Truthfully, it is not always fun but rather a lot of hard work.

 

 

So, you should appreciate the process/progress of learning to enjoy it, instead of taking it as hard work.

[imatfaal]

Nicholas

 

It isn't all change at university - here is a page with Walter Lewin's three first year physics courses at MIT. I have done them all through edx.org and apart from when mentioned from passing interest it is all classical and the mechanics is newtonian. So at one of the best schools in the USA you hardly touch Einstein and only chat about QM etc in the whole of the first year - it isn't such a big change. I guess those concentrating on physics may do option courses that do breach these subjects - but not sure as US education a bit of a unknown for me

 

http://web.mit.edu/physics/people/faculty/lewin_walter.html

[ajb]

So, why not teaching some basic knowledge at high school?

Again, you don't yet have the tools.

 

Try asking your students or simply conduct a survey then you will know the truth. Remember that the whole classical physics of high school is being overturned by modern physics of university, except some basic fundamental concepts that persist ever since it is being taught.

When I studied for an undergraduate degree in physics it was not exactly overturning all of high school physics. Rather we build on top of what we already knew and explored some aspects in some detail. I think most of us were quite open to quantum mechanics and relativity theory, but then for a lot of the class the main thing was to get through rather than debate the subtleties of the Universe. That comes later in grad school.

 

So, you should appreciate the process/progress of learning to enjoy it, instead of taking it as hard work.

It is enjoyable, but frankly it can be hard work. Nothing worth doing is easy...