How Does Light and Time Affect Our Perception of Reality?

In summary, light reflects off of objects and hits your eyes. Your eyes detect light. But also, objects emit light and your eyes can detect that too. Light takes time to travel over distances, it does not travel instantaneously. The further the light has to travel, the longer it will take. The best angular separation that you can resolve is a function of the width of the telescope and the wavelength of light you are using. For visible light with a wavelength of 580 nanometers and a telescope with an aperture the size of the earth, your resolving power at 2 light years is only good enough to resolve an object about 100 times the size of the Earth (assuming I haven't slipped a few digits somewhere).
  • #1
CRL
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Can someone please explain how vision works? When we see everyday objects how does it work? Is light reflected off the objects and then back into our eyeballs?!? I always heard when you look up to the stars it's like looking into the past. Even our sun, when we see the sun we're seeing the sun as it was 8 minutes ago. Can someone explain this further? And When we see everyday objects are we seeing them as they were billionths of a second into the past? And if so, is this due to the brains processing speed, or what causes that? And if looking great distances away is like a time machine...say there was a gigantic mirror in space that is 1 light year away and we had a really good telescope, could we look at that mirror and see Earth 2 years into the past? This is so very interesting to me, any response would be greatly appreciated. :)
 
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  • #2
Yes, light reflects off of objects and hits your eyes. Your eyes detect light. But also, objects emit light and your eyes can detect that too. Light takes time to travel over distances, it does not travel instantaneously. The further the light has to travel, the longer it will take.
 
  • #3
CRL said:
Is light reflected off the objects and then back into our eyeballs?!?

Yes. The light from the object reflects. Part of that light strikes in the area of your pupil. This is the hold in the center of the iris through which you see. Your pupils adjust to brightness, getting narrower in bright light and wider in dim light. This helps equalize the illumination levels on the retina, preventing damage in bright light while helping you see better in low light.

The light then passes through a lens in your eye. This is immediately behind the pupil. It acts to take diverging rays of light coming from a point in your field of view and cause those rays to converge on a point on your retina. If there is an object in your field of view that is reflecting light toward your eye, the lens will focus that light on a point in your retina.

Light sensors on your retina detect this illumination and send a signal toward the brain throguh the optic nerve.

say there was a gigantic mirror in space that is 1 light year away and we had a really good telescope, could we look at that mirror and see Earth 2 years into the past?

There is a problem -- diffraction. The best angular separation that you can resolve is a function of the width of the telescope and the wavelength of light you are using. For visible light with a wavelength of 580 nanometers and a telescope with an aperture the size of the earth, your resolving power at 2 light years is only good enough to resolve an object about 100 times the size of the Earth (assuming I haven't slipped a few digits somewhere).

Rather than standing up a huge mirror 2 light years out and putting together a huge telescope to look into it, it's a whole lot more cost effective to put a camera on the street corner and save the tape for a couple of years.
 

1. What is light and how does it travel?

Light is a form of electromagnetic radiation that is visible to the human eye. It travels in a straight line at a constant speed of approximately 299,792,458 meters per second (m/s) in a vacuum.

2. How do we see objects?

When light reflects off an object, it enters our eyes and is focused onto the retina, which contains light-sensitive cells called rods and cones. These cells convert the light into electrical signals that are sent to the brain, where they are interpreted as images.

3. What is the speed of light and why is it important?

The speed of light is approximately 299,792,458 m/s, and it is important because it is the fastest possible speed at which all matter, energy, and information in the universe can travel. It also plays a crucial role in many scientific theories and equations, such as Einstein's theory of relativity.

4. How does light affect our perception of time?

According to Einstein's theory of special relativity, time and space are relative to the observer's frame of reference. This means that the speed of light is constant for all observers, regardless of their motion. As a result, the closer an object moves to the speed of light, the slower time appears to pass for that object from an outside perspective.

5. Can light travel through different mediums?

Yes, light can travel through different mediums, such as air, water, and glass. However, the speed of light will change depending on the medium it is traveling through. This is due to the different densities and refractive indexes of these materials, which can cause the light to bend or slow down as it passes through them.

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