I Instrument Size & Wavelength: What's the Relationship?

accdd
Messages
95
Reaction score
20
What is the relationship between the size of the instrument and the wavelength you want to measure? Both in general relativity and in other areas.
 
Physics news on Phys.org
There are many limits which look like Heisenberg Uncertainty relations that follow from the Cauchy-Schwartz Inequality. Like diffraction limits for a camera.
What is your particular question?
 
  • Like
Likes Vanadium 50, vanhees71 and accdd
Why do we need large instruments to detect waves with large wavelengths? Why can't we detect smaller wavelength waves with large instruments (and viceversa)?
I have also read that some instruments must have dimensions comparable to the wavelength that allows the phenomenon of resonance. What are the general principles for sizing an instrument?
 
accdd said:
Why do we need large instruments to detect waves with large wavelengths? Why can't we detect smaller wavelength waves with large instruments (and viceversa)?
For the same reason that one cannot make a piccolo sound like a tuba.
accdd said:
I have also read that some instruments must have dimensions comparable to the wavelength that allows the phenomenon of resonance. What are the general principles for sizing an instrument?
It depends upon what you are trying to optimize. There are fundamental limits that deal with noise and information. Resonance allows maximizing signal to noise but the cost is specificity of detection.
 
  • Like
Likes PeroK, Vanadium 50, vanhees71 and 1 other person
hutchphd said:
For the same reason that one cannot make a piccolo sound like a tuba.
Did you know that the opening of The Rite of Spring by Stravinsky is a bassoon played in a high register?

 
  • Like
Likes hutchphd, Sagittarius A-Star and vanhees71
PeroK said:
id you know that the opening of The Rite of Spring by Stravinsky is a bassoon played in a high register?
Hence the rioting at the premiere.
 
  • Haha
  • Like
  • Informative
Likes Sagittarius A-Star, hutchphd and PeroK
I asked a question here, probably over 15 years ago on entanglement and I appreciated the thoughtful answers I received back then. The intervening years haven't made me any more knowledgeable in physics, so forgive my naïveté ! If a have a piece of paper in an area of high gravity, lets say near a black hole, and I draw a triangle on this paper and 'measure' the angles of the triangle, will they add to 180 degrees? How about if I'm looking at this paper outside of the (reasonable)...
From $$0 = \delta(g^{\alpha\mu}g_{\mu\nu}) = g^{\alpha\mu} \delta g_{\mu\nu} + g_{\mu\nu} \delta g^{\alpha\mu}$$ we have $$g^{\alpha\mu} \delta g_{\mu\nu} = -g_{\mu\nu} \delta g^{\alpha\mu} \,\, . $$ Multiply both sides by ##g_{\alpha\beta}## to get $$\delta g_{\beta\nu} = -g_{\alpha\beta} g_{\mu\nu} \delta g^{\alpha\mu} \qquad(*)$$ (This is Dirac's eq. (26.9) in "GTR".) On the other hand, the variation ##\delta g^{\alpha\mu} = \bar{g}^{\alpha\mu} - g^{\alpha\mu}## should be a tensor...
Back
Top