# Distance, Time relation and light.

1. Dec 12, 2011

### maxcy03

When we stand in front of a mirror, the image reflected is not us, it was the past of us, im sure u guys already know that, like I stared at my friend and he stood very far away from me and all his actions were 'delayed' for a very very short time coz light needs time to travel.

How bout I stand very far away frm a mirror so that all my actions are delayed for 3 seconds and I smile and I sprint swiftly to reach a meter away from the mirror in 1 sec. Can I see all my images include the smiling one? assume that I hv great sigh and muscles. my speculative idea ' the greater the distance, the longer the time taken for an observer to see the change'.

Another question. What is our human vision and light 'refresh rate'. Why when an object almost achieve the speed of light, time slows down? Because light is the true constant? Is that object's time slows down just on our sigh?

Hope u comprehend and kindly answer.

Last edited: Dec 12, 2011
2. Dec 12, 2011

### JHamm

If it takes light 3 seconds to go to the mirror and back then you could just stand in one spot and get the same effect, moving a meter forward is entirely negligible when light moves at 300,000,000 m every second

3. Dec 12, 2011

### maxcy03

lol, be cool. sry my language isn't that good,btw I didn't mean that. What I trying to say is that I run 899999999 meter (since the distance between me n the mirror is 900000000m) so that im 1 meter away frm the mirror.

4. Dec 12, 2011

### Lsos

Countless times I've tried desperately to see in the mirror if I have a bald spot on the back of my head, but I was just never quick enough. If the mirror was very very far away I don't see what it wouldn't work.

5. Dec 12, 2011

### maxcy03

I think it will work if we hv some kind of gadget like camera to help us,btw i need good answers and explanations.

6. Dec 12, 2011

### Staff: Mentor

You could never do this practically because of the great speed or distance you would need. You can't reach a high enough speed to see this effect in your home mirror, and any mirror you place 3 light seconds away would look so small that you would need a very very large telescope to even see it. Not to mention the fact that unless you were glowing like the Sun there wouldn't be enough light reflecting off of you, getting to the mirror, then reclecting back to see anything.

However, the idea is mostly sound. Given a large distance, you would see a time lag. Since there aren't any mirrors floating around in space we don't see reflections of us. (Not in a picture in mirror effect at least) We do however have time lag between Earth and anything out in space. The apollo astronauts had a time lag of about a second between transmit and receive times, and it only gets worse the further things are. For example, it takes over an hour for signals sent from Earth to reach the Cassini-Huygens spacecraft at Saturn. Total round trip time is 2-3 hours, requiring us to send pre-programed instructions to the spacecraft since we cannot control it in real-time.

7. Dec 13, 2011

### maxcy03

thx dude. Hmm 1 more thing, is everything that we observe around us is their past? Since light need a very very short time to travel.Am I rite?

8. Dec 13, 2011

### Staff: Mentor

I believe that is one way to look at it. I am not familiar enough with Relativity to really be sure. I think there are a couple of different ways to view time.

9. Dec 13, 2011

### JHamm

The light that you are now seeing was emitted in the past, things might not be exactly how they appear to you (seeing light from dead stars etc...) now so yes you could say you are looking in to the past.

10. Dec 13, 2011

### maxcy03

Gracias

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