Can you help me to understand red shift of light? (in layman's terms)?

Question

I do know that it cannot work on the same principle as the Doppler effect because one cannot add to the motion of light,
Thus the speed of the object moving away can't have an effect. I see that some say that space is expanding between the object and the observer. How does this happen and if we observe blue shift, does that mean that space is contracting ?

I quote from WIKIPEDIA
These galaxies are not receding simply by means of a physical velocity in the direction away from the observer; instead, the intervening space is stretching, which accounts for the large-scale isotropy of the effect demanded by the cosmological principle.

Answer 1

The easiest way to understand red shift is by thinking of light as electromagnetic waves. The speed of these waves are always constant but the frequency can change.

For example, if you run into the ocean you meet each wave faster than if you were standing still, this has the effect of increasing the frequency of the wave. When an object that is emitting light moves towards us at high speeds the waves of light get compressed and change to a higher frequency. This is similar to the Doppler effect. When the sound waves are being emitted by a moving object such as a ambulance passing, the speed of the sound waves are not changing much but their frequency is changing. As the ambulance is coming towards you you hear a higher pitch (frequency) which is the analog of the blue shift. As the ambulance moves away the waves get stretched out and you hear a lower pitch, the analog of red shift.

Current theories suggest that the universe is constantly expanding thus is the space in between the galaxies. This has the same effect as if the galaxies were receding from each other and what causes the redshift. There is no current theories that include large scale contractions of space, so if we observe a blue shift we take it to simply mean that that object is moving towards us.

Answer 2

It is exactly the same as the Doppler effect. The speed of light is not affected but the frequency is. The shift in frequency if it is going away goes towards the red. Blue means it is coming at us.
It tells nothing about space contracting, it just tells us the relative speed between us and the object being observed.

Answer 3

Laymans terms:
Red shift = object moving away from you
blue shift= object moving toward you

The space between the observer and object is not expanding or contracting...only the distance is changed.

An easy way to think about the shifts, is waves. Light travels in a wave pattern. If you were at the beach, running/swimming into the ocean, the distance between waves might be constant, but wou would hit more waves in a shorter time period. (ie blue shift)

Now as you head back to shore, you are moving away from the constant waves, and waves pass you at a lower rate while heading toward shore....the frequency of which the waves hit you is drawn out because you're moving away. (ie red shift)

Answer 4

Consider an object at rest with respect to you and assume it emits a signal with a wavelength of one. You measure the wavelength as one. Now assume it starts moving away from you at one tenth the speed of light. Over the time it takes for one cycle to happen, the source has now moved away so in effect the light wavelength gets stretched out. The speed of light is the same but the wave gets stretched out and shifted toward the red.

Answer 5

an easy way to look at the red shift is like a train coming at you. the whistle gets high as it passes. and the whistle gets longer after it passes. that is the doppler effect. the galaxies are reciding from us, because we are also moving away from the observed galaxy. so if galaxies or stars are coming towards us, they are blue shifted.

Answer 6

the 1st unquestionably laboratory verification of the Doppler shift for mild became back in 1901 by making use of a chap talked approximately as Bélopolsky. He used rotating mirrors and it wasn't that precise. yet greater laboratory verification persisted and greater. in case you leaf interior the direction of the rfile interior the link, it provides a sprint bit the historic previous and shows some (now very previous college) equipment suitable to be utilized by making use of physics scholars to do the test. i've got faith the rfile dates back to the time of the 1st international conflict greater or less.

Answer 7

Actually, the Doppler effect is the closest thing towhich i can compare it... as galaxies recede from each other, the light they emit loses energy, and goes from purple (hi energy) towards red (lo energy).