An example of moving towards a light source

In summary, Ich explains that if you drive towards a speed close to that of light, you'll see that the color of the traffic light will change. However, if you drive away from the light, you'll see that the color of the traffic light will stay the same.
  • #1
atomqwerty
94
0
Hi,

I've a question that I'll illustrate by presenting the following example:

Let's imagine Einstein in a car that's moving away from a clock. This clock 'send' a light beam with the information 'It's 12 o'clock'. If the velocity of this car is close to c, I understand that Einstein will be driving beside the light beam, therefore beside the information, always seeing that the time is 12 o'clock, no changes. But, and this is my question, if Einstein drives towards the clock (close to c, too), will he see the events accelerated on the reference system of the clock (-earth)? why? I mean, einstein's only moving to the light: the only thing that he'll notice is that the information of '12 o'clock' will arrive earlier to his eyes...

Thanks
 
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  • #2


Hi atomqwerty, welcome to PF!

What you're describing is the http://en.wikipedia.org/wiki/Doppler_effect" . You see the clock faster or slower, depending on direction.
Only after you correct for the light travel times, you conclude that the clock ticks slower from your perspective. This is time dilation, and independent of direction.
 
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  • #3
Thank you, Ich :)
You mentioned the Doppler effect and if that effect only implies a change of the wavelenght that comes from a source of light (em field) or sound, would you see, for example, that the red color of a traffic light has turned into a green light if you'd drive at a huge speed?
 
  • #4
would you see, for example, that the red color of a traffic light has turned into a green light if you'd drive at a huge speed?
Yes.
Actually, that was an exercise in my relativity textbook in school. The driver got away without a ticket, IIRC.
 
  • #5
Ich said:
Yes.
The driver got away without a ticket
.(for ignoring lights) but got a huge one for speeding
 
  • #6
thecritic said:
.(for ignoring lights) but got a huge one for speeding

Hahaha! :D
 

What is an example of moving towards a light source?

An example of moving towards a light source is when a plant bends towards the direction of sunlight in order to maximize its exposure to light for photosynthesis.

What is the purpose of moving towards a light source?

The purpose of moving towards a light source is to increase the amount of light that an organism receives, which is necessary for processes such as photosynthesis and vision.

What types of organisms exhibit movement towards light sources?

Plants, insects, and some animals such as birds and fish are known to exhibit movement towards light sources.

How do organisms sense light and determine the direction to move towards it?

Organisms have specialized cells or structures, such as photoreceptors, that can detect light and send signals to the brain or other parts of the body to initiate movement towards the light source. These cells are sensitive to the direction, intensity, and wavelength of light.

What are the benefits of moving towards a light source?

Moving towards a light source can provide organisms with the necessary energy for survival and growth through processes like photosynthesis. It can also help them orient themselves and navigate their environment.

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