what is the difference between observable and visible(in astronomy or in physics)

 

my native language is not english..that's why, I don't get it

Very roughly: Visible often means you can see it with your naked eye; sometimes this also includes the aid of magnification. Observable means it can be detected, though it may require instrumentation.

 

I don't think there are precise definitions that always apply, though.

Very roughly: Visible often means you can see it with your naked eye; .

for example,the sun,the moon ..is it true?

sometimes this also includes the aid of magnification. .

I didn't understand

Observable means it can be detected, though it may require instrumentation..

for example ,Quantum Physics General Relativity..is is true?

Edited January 17, 200917 yr by devrimci_kürt

what is the difference between observable and visible(in astronomy or in physics)

 

my native language is not english..that's why, I don't get it

 

Visible is what you can see with you eyes.

 

Observable (physics) (as defined by Bookshelf)

A physical property, such as weight or temperature, that can be observed or measured directly, as distinguished from a quantity, such as work or entropy, that must be derived from observed quantities.

 

Edit - You can observe the automobile with your eyes or your hands but it is visible only with your eyes.

Edited January 17, 200917 yr by NowThatWeKnow

One might say that things are visible, even if a telescope or microscope are needed. That's what I meant by "aid of magnification."

Obervable can be something that is not visible for the naked eye (even with the help of a telescope) but *is* visible when we apply a filter, like, for instance, in X-Rays or Gamma Rays, etc.

 

You won't see it in space with a telescope, but if you set your equipment to intercept Gamma Rays, X Rays or Infra Red, etc, suddenly you'll see it on your monitor..

 

Does that help?

With respect to observable I'm a tad unclear as to what is the un-observable universe and is it possible to determine it's size. For that matter what's the size of the observable universe?

 

Thanks.

In this kind of discussion, context is important. How are the words being used? hat may help focus the answers.

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With respect to observable I'm a tad unclear as to what is the un-observable universe and is it possible to determine it's size. For that matter what's the size of the observable universe?

 

Thanks.

 

Observable universe is 46.5 billion LY across. The unobservable universe is beyond our view because of the expansion of space.

http://en.wikipedia.org/wiki/Observable_universe

 

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