This is a question that I always pondered about.
In the phenomenon of refraction, light bends away from the normal to make up for the increase in speed when it enters a rarer medium. Is this something really fundamental to physical laws…..
…. or is there a reason for light to show “signs of sentience”?
Update:
Umm.. to the intel_knight: Hey! I am not saying light is smart… hehehe… but how does it know that it should bend away from the normal to reach a little late to wherever it was going to make up for the increase in speed it received entering the new medium.
I dunno… is this a stupid question?
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No its not stupid at all!
“ForPeace” is right about density of medium.
You will surely have to slow down your car in a slow moving traffic!
In physical terms more the density, more is the obstruction to the photons and more energy dissipation in that medium.
In fact a denser medium decreases the energy of photons and hence of the light.
“For peace” explanation although crude does the trick.
Relativistic consideration make the proof better.(although im not delving into it)
For the velocity decrease to be possible, angular deviation is the best possible way which can be easily proved by wavefronts theory (and the fact that planarity is to be maintained).
Infact it comes to my memory that this proof(by wavefront theory) was there in my std.11 syllabus(Maharashtra board) it comes by simple geometry and a bit of SNELL’s Law.
Ratio c/u remains constant for light in any medium
c = velocity of light in a medium
u = refractive index of that medium
So it definitely proves that light is not SENTIENT!
Source(s): I see that u have already extended the time duration of Q!
Light always travels in a straight line at a speed of 3X (X= 10^8m/sec)
The appearance of light having changed direction during its motion is an Optical Illusion percieved by the limits of the human eye.
Regarding the reason for light to show “Signs of sentience” it can be concluded that light has a sense of respect for the laws of physics.
To add to your thoughtful theory, Light also has the discipline of observing the rules of traffic movement. This can be inferred from the theory of relativity that states that when an object attains the speed of light and continues to travel in space then its mass becomes infinite and the progress of the physical object is halted to zero. Imagine the truth in the statement that the speed of an object travelling at the speed of light is instantly reduced to Zero when its mass becomes infinite. This is because the laws of physics have fixed the speed of light. Whenever there is a threat to the light speed barrier from an object moving near the speed of light, its motion is arrested and the other object is unable to break the speed record set by light.
Apart from this phenomenon being a law of physics, it is more of an Universal Law
Source(s): e=mc^2
Light is part of our physical universe. It behaves just like any matter. Just like a comet or meteor does. It will bend due to a stars gravity, it will disperse and stop when you put heavy opaque drapes on your windows, it will be absorbed into a ‘black hole’ if it gets to close to it.
It is not sentient on its own… but the Universe might be!
Yours truly;
Jonnie
The bending is predicted in Maxwell’s equations. If you look at the boundary of materials and solve for the the E and B Fields on both sides of the boundary you will see that has to light bend.
This a GREAT question! I would recommend the book “QED: The Strange Theory of Light and Matter” by Richard Feynman. Light is even weirder than your question implies… Richard Feynman does a great job explaining the most complex physics theories.
well,u urself had pointed out that there is an increase of speed in the light when it travels in rarer medium..yes…dont u think u can go faster on a road where there is less traffic..???
it all depends on the density of the medium..
also,let me put it this way to make it clear..
i ll give u the realationship between density and velocity(or speed but exactly to say,velocity)
density=mass/volume
we know, mass = force/acceleration.
so,
density = force/acceleration x volume
acceleration = velocity/time.
from this,
density = force x time
——————
velocity x volume
from this,
density is inversely proportional to velocity.
so,rarer medium,more speed….denser…less speed..
i donno how far this helps u…
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Let L = length of shadow. x = her dist from lamp. => x/L = 5/11. => 5L = 11x. => 5dL/dt = 11dx/dt. => dL/dt = 11*5/5 = 11 ft/sec. It is constant and doesn’t depend on her dist from lamp.
light bends because one side of the beam reaches the surface before the other does, and then starts moving at a different speed.
if light was smart, it would refract when it hits the suface at right angle.