A
"Aqua Boy"
Guest
anyone want 2 talk about non expansion theory. eg if light speed is not a constant, then how can we judge expansion by dopler shift ??
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A
afthefragile
Guest
The speed of light is constant.
Doppler shift is the apparent shift in the frequency of light to us causing by the movement of us or the source of the light towards of away from us.
When galaxies are moving towards us, the frequency of their light looks increased to us, pushing their light towards the higher (blue) end of the light spectrum. This is called the blue shift.
It is used to see which galaxies are moving towards us.
When galaxies are moving away from us, the frequency of their light looks reduced to us, pushing their light into the lower (red) end of the light spectrum. This is the red shift.
The galaxy appears more red than usual indicating it is moving away from us.
This is how Hubble found out the universe was expanding.
In every direction he looked, he observed galaxies moving away from us (the red shift). And he concluded in a complex way that the universe is expanding (it was a bit more complex than looking in every direction and seeing everything go red).
And now it has been discovered that the universe is expanding faster with time. And so was the invention of Dark Matter and Dark Energy.
Doppler shift is the apparent shift in the frequency of light to us causing by the movement of us or the source of the light towards of away from us.
When galaxies are moving towards us, the frequency of their light looks increased to us, pushing their light towards the higher (blue) end of the light spectrum. This is called the blue shift.
It is used to see which galaxies are moving towards us.
When galaxies are moving away from us, the frequency of their light looks reduced to us, pushing their light into the lower (red) end of the light spectrum. This is the red shift.
The galaxy appears more red than usual indicating it is moving away from us.
This is how Hubble found out the universe was expanding.
In every direction he looked, he observed galaxies moving away from us (the red shift). And he concluded in a complex way that the universe is expanding (it was a bit more complex than looking in every direction and seeing everything go red).
And now it has been discovered that the universe is expanding faster with time. And so was the invention of Dark Matter and Dark Energy.
The speed of light as a constant is just a theory. Give me a shout when you get to Alpha Centuri and we'll try to prove it.
Expansion and Doppler shift appear (as does the speed of light) to be constant because we can see differences while measuring celestial bodies. Because we see a great degree of red shift in some objects and less in others we presume them to be closer or nearer.
No one has proven squat! It just fits nicely onto the theoretical equations.
I, personally, believe we're overdue for another relativity and quantum mechanic overhaul of the entire field.
Expansion and Doppler shift appear (as does the speed of light) to be constant because we can see differences while measuring celestial bodies. Because we see a great degree of red shift in some objects and less in others we presume them to be closer or nearer.
No one has proven squat! It just fits nicely onto the theoretical equations.
I, personally, believe we're overdue for another relativity and quantum mechanic overhaul of the entire field.
Edwin hubble's famous experiment...
he let the light of a star on a spectrometer, what he noticed is that the light is shifting to red.. and this means that us and the star are getting farther apart. And so are the rest of the cosmic bodies. Everything in the universe (galaxies, stars, black holes) is moving apart, which then gave us a prediction of the expanding universe.
Edit: the frequency (or number of waves per second) of light is extremely high ranging between four and seven hundred million million waves per a second, the different frequencies of light are what humans eyes see as colors, the lowest frequencies appear red and the highest appear blue..
there's a good explanation of the idea of a Red shift :
Let's say you're standing still. Cars are coming down the road once every second. Now you get in your bicycle and try to race them. You aren't fast enough to win so they keep passing you. They pass you less often though. Their frequency has gone down. That's a red doppler shift.
Likewise, in astronomy light from stars is coming at us. The Earth is getting farther from most of them because the universe is expanding, so their frequency goes down.
he let the light of a star on a spectrometer, what he noticed is that the light is shifting to red.. and this means that us and the star are getting farther apart. And so are the rest of the cosmic bodies. Everything in the universe (galaxies, stars, black holes) is moving apart, which then gave us a prediction of the expanding universe.
Edit: the frequency (or number of waves per second) of light is extremely high ranging between four and seven hundred million million waves per a second, the different frequencies of light are what humans eyes see as colors, the lowest frequencies appear red and the highest appear blue..
there's a good explanation of the idea of a Red shift :
Let's say you're standing still. Cars are coming down the road once every second. Now you get in your bicycle and try to race them. You aren't fast enough to win so they keep passing you. They pass you less often though. Their frequency has gone down. That's a red doppler shift.
Likewise, in astronomy light from stars is coming at us. The Earth is getting farther from most of them because the universe is expanding, so their frequency goes down.