[Catalist] FW: Gravity

[Chris Creagh]

Hi John

I think I am being misquoted? Optional? I said horses for courses. Perhaps David puts it more eloquently than I. Anyway it is late, good on you David for the excellent Einstein-First project and for your passion for physics.

Regards
Chris


From: Catalist [mailto:catalist-bounces at lists.stawa.net] On Behalf Of John Clarke
Sent: Wednesday, 17 August 2016 4:46 PM
To: catalist at lists.stawa.net
Subject: [Catalist] FW: Gravity

Hi All,
I missed the start of this discussion and have some feed back from Professor David Blair that I'm sure will be of interest.
I will also take the opportunity to advertise an upcoming International workshop in this teaching area. It precedes Future Science and indeed concludes at Future Science. For more detail follow the link: http://www.cvent.com/events/international-workshop-on-the-teaching-and-learning-of-einsteinian-physics-in-the-era-of-gravitation/agenda-4f6ed0abf23c4c999ea4fcf4dcf9fcb6.aspx

Chris Creag's idea that Einstein's general relativity is optional, to be used when relevant is like saying that it is optional to teach that the Earth is a ball, and not flat. Students need to know the beautiful, simple and satisfying concepts of general relativity because they are our best understanding of reality. We need to separate the underlying ideas from the tools. When it comes to solving problems, we all need to know which approximation to use. Architects and golfers can use flat earth models and Newtonian space-time, radiation oncologists must use relativistic equations,  and GPS designers and anyone interested in the new frontier of gravitational wave astronomy can only talk about it in the context of curved space and warped time.


In the Einstein-First project we start year 7's with the whole conceptual understanding of general relativity...they just take it in their stride and they love it! Later they can find out how the old idea of gravity as a force came about, and how it is useful to think that way.
Newton has definitely not won the day, Alan!  The discovery of gravity waves marked his demise.


>From Nov 30 to 2 Dec  we are holding a special workshop for teachers:  Teaching and Learning Einsteinian Physics in the Age of Gravitational Wave Astronomy. See the STAWA web site for details.

David Blair
Winthrop Professor
Director, Australian International Gravitational Research Centre (WA Government Centre of Excellence)
david.blair at uwa.edu.au<mailto:david.blair at uwa.edu.au>
david.gerald.blair at gmail.com<mailto:david.gerald.blair at gmail.com>
Tel: 61 8-6488 2736 (office)
       61 8-9575 7591 (Gingin)
       0409 687 703 (Mobile)
Office: 61 8 6488 1170
Home: 61 8 9279 1003
M013
School of Physics
University of Western Australia
35 Stirling Highway
Nedlands, WA6009
www.gravity.uwa.edu.au<http://www.gravity.uwa.edu.au/>
www.aigo.org.au<http://www.aigo.org.au/>
www.seeproject.org.au<http://www.seeproject.org.au/>

Begin forwarded message:

From: Chris Creagh <C.Creagh at murdoch.edu.au<mailto:C.Creagh at murdoch.edu.au>>
Subject: Re: [Catalist] Gravity
Date: 16 August 2016 at 4:03:56 PM AWST
To: "catalist at lists.stawa.net<mailto:catalist at lists.stawa.net>" <catalist at lists.stawa.net<mailto:catalist at lists.stawa.net>>
Reply-To: catalist at lists.stawa.net<mailto:catalist at lists.stawa.net>

Hi Alan

The way I look at it is "horses for courses". Use the model that works for what you are trying to understand/describe/work with at the moment. We use these models to understand the world around us and make predictions/look for relationships/allow us to operate in the world. So why use General Relativity when Special Relativity does the job? Why use Special Relativity when Newtonian Relativity is adequate?

So if the attraction (force) between two masses is adequate for the level you and your students are working at then let that be the model to work with. You might hint to the students that there is a deeper understanding if they wish to go and look for it though, just to keep them guessing.

I think philosophically we can never know precisely the nature of the world around us. We can only know what we perceive and use our understanding of science to make models that explain our observations.

I am not sure that helped much but it gave me a nice break from electronic "paperwork".

Regards
Chris Creagh
www.physcom.net<http://www.physcom.net/>




From: Catalist [mailto:catalist-bounces at lists.stawa.net] On Behalf Of Alan Gent
Sent: Tuesday, 16 August 2016 3:38 PM
To: Catalist at lists.stawa.net<mailto:Catalist at lists.stawa.net>
Subject: [Catalist] Gravity

Can somebody please explain whether gravity is in fact a force? My understanding is that it Einstein showed that gravity is an effect of the curvature of space-time - and that was way back in the early 1900s, yet notables such as Professor Brian Cox consistently refer to the 'force of gravity'. There was also a recent program on ABC I believe, concerning 'anti-gravity' and in the program there was absolutely no mention of Einsteinian physics, and constant referral to 'gravitational force'. I actually thought it was rather a childish program.
Can we now assume that Newtonian physics has won the battle and we can really forget about Einstein, unless it suits us not to?
I realise not many teachers promote Einsteinian physics, it being in the 'too hard basket', but is there somebody out there that can enlighten me?
If gravity is actually a force, then there's no point in even mentioning theories of relativity, is there?

Alan Gent.
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