
#1
Jul2713, 09:24 PM

P: 5

Hello everybody,
Based of some information that I recently learnt(which I don't know if they are right or wrong), I start asking myself this question about the euclidean geometry. Ok, this geometry is basically founded on straight lines, and what I have learnt is there is no such a thing as a straight line in our planet.So.alot of human activities is based on this geometry,and it does really work after all but only for our eyes , so there must be some mistakes but very little one that we can't observe,because they very tiny .So ,my question is , when will the euclidean geometry become useless ? I mean if it is making some little mistakes some where ,then there must be cases which the mistakes can no longer be hidden Or I am just talking randomly and all this question is based on mistaken information, please do enlighten me. Thanks in advance. 



#2
Jul2713, 09:42 PM

Mentor
P: 16,692

Of course, we use Euclidean geometry where it's applicable. And that is: on small scales. So if we want to build a house, then our notions of parallel and perpendicular work, because the scales are so small.
However, if we start to go to larger scales (like: larger distances), then Euclidean geometry breaks down. A classical and historical example is for a ship to find the shortest distance between two points. Here, the curvature of the earth comes into play and things are much more difficult than in Euclidean geometry. 



#3
Jul2713, 09:49 PM

P: 5





#4
Jul2713, 09:51 PM

Mentor
P: 16,692

when will euclidean geometry become...?
I guess we would use some kind of spherical geometry. Do you have any concrete example of such a structure?




#5
Jul2713, 09:56 PM

P: 5





#6
Jul2713, 09:58 PM

Mentor
P: 16,692





#7
Jul2813, 04:10 AM

HW Helper
P: 1,373

An example is microwave towers. How do you know where to point the microwave dish? You can't just point it parallel to the ground, it won't find the other tower.




#8
Jul2813, 06:58 AM

P: 234





#9
Jul2813, 07:03 AM

P: 234

Euclidean Geometry's usefulness is not its application to real world solutions, necessarily. It's beauty lies in the mathematical structure it created and the concept of proof. The rigor of the geometric proof, sadly, is not taught anymore in schools. Just because the politics in control of schools see no use for it does not mean it is not a worthwhile endeavor. It is a great foundation for all things mathematical.




#10
Jul2813, 09:00 AM

Engineering
Sci Advisor
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Thanks
P: 6,383

There is nothing wrong with the "math" in the examples in #2 an #7, but in my view they are both Euclidean geometry. Euclid's "Elements" is not just about "straight lines". The second book (out of 13) is mostly about circles, and it progresses to 3D geometry.
Engineers use Euclidean geometry every day in situations that are much mode complicated than just the surface of a sphere (i.e. the earth, in the two examples). IMO the only applications of nonEuclidean geometry in Physics would involve special or general relativity. I think the OP (and others) may be confusing "Euclidean geometry" with "geometry of a two dimensional plane". 



#11
Jul2813, 03:18 PM

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P: 2,693





#12
Jul2813, 11:05 PM

P: 234

Geometry was refined by Hilbert to those essential Postulates and Theorems necessary for geometric proofs. In all of the geometric proofs numbers never appear as the measure of anything. Only references to right angles or n times an object. as in surface of a sphere is 4 times that of a great circle. 



#13
Jul2913, 01:32 PM

HW Helper
P: 1,373




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