Speed of Light and Age of Universe

Originally posted by DoctorScribbles
ROFL, really, you think the universe was created 7K years ago? I don't, so I don't subject my conclusions to being consistent with that premise.

[b]I am giving you light is constant and that you are getting the speed
of light correct, it is just what you think it is, but all of that does
not mean that you know the age!

This is purely sk ...[text shortened]... neither of (1) or (2) hold. Can you give me any non-skeptical argument that they do hold?[/b]

You have read how and why the stars were created?
You tell me, if that is true, how old would the light that is currently
hitting the earth be, billions of years old, or several thousand? If it
were true, could you tell the difference simply by looking at the light?
I am being skeptical, and your belief that you know the history of the
light hitting the earth is presumptuous.
Kelly

Originally posted by KellyJay
You have read how and why the stars were created?
You tell me, if that is true, how old would the light that is currently
hitting the earth be, billions of years old, or several thousand? If it
were true, could you tell the difference simply by looking at the light?
I am being skeptical, and your belief that you know the history of the
light hitting the earth is presumptuous.
Kelly

Your belief that you know that you had a great grandfather is presumptuous.

Originally posted by scottishinnz
well, if a star is 50,000 light years away, and we see the light today then either the universe is at least 50,000 years old, or god's up to his old tricks of faking the evidence again. Why Kelly, when we've got observations about the distance of stars, convergent radiodating estimates for the age of the earth etc, do you still maintain a 7,000 year old universe??

Scott,

Could you please explain how we know something is 50k light years away? I think this is the
stumbling block. That is (and I do not know, otherwise I would offer it), how do we know that
the light that reaches us is 50k years old and not 5k years, say?

Nemesio

Originally posted by KellyJay
I am interested in how you measure light's speed, is it is
calculation from other measurements, or do we have something
quick enough to react to capture the rate of how fast light travels?
Kelly

According to http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/measure_c.html
the speed of light was directly measured on earth as long ago as 1849.
There are many many other ways to measure it and being one of the fundamental constants of the universe it has been verified in many different ways and much of science is based on knowing it. Nuclear physics (E=mc^2) is a nother independant way of measureing the same constant without speed ever coming into it.

If the speed of light is constant and we know the distance it has covered from its source, then yes we do know the age. So are you denying basic physics, denying the distance, or denying the constancy of the speed of light or just being vague? Over the course of about 4 posts you keep implying something is wrong but wont say exactly what.

Originally posted by Nemesio
Scott,

Could you please explain how we know something is 50k light years away? I think this is the
stumbling block. That is (and I do not know, otherwise I would offer it), how do we know that
the light that reaches us is 50k years old and not 5k years, say?

Nemesio

We can measure the parallax of a star directly, the hiparcos satellite has already done that for thousands of stars and newer ones coming up will make even finer measurements meaning it measures stars ever farther away from earth. When the Earth goes round the sun, if you take a pic of a star and then do it again 6 months later you have a triangulation based on the change in position of the earth by some 186 million miles so you have a long skinny triangle with the base near 200 million miles and the long legs trillions of miles long, very skinny triangles indeed but the measurement accuracy is getting so good we can measure directly the distance to stars a thousand LY away and that will get so good in a few more years we will be able to directly measure the distance to the center of the galaxy. All that not depending in the least bit on colors, doppler shifts, intensity, none of those properties of the light given off by a star comes into play, just the apparent movement of the star by the earth's rotation around the sun.

Originally posted by sonhouse
We can measure the parallax of a star directly, the hiparcos satellite has already done that for thousands of stars and newer ones coming up will make even finer measurements meaning it measures stars ever farther away from earth. When the Earth goes round the sun, if you take a pic of a star and then do it again 6 months later you have a triangulation base ...[text shortened]... comes into play, just the apparent movement of the star by the earth's rotation around the sun.

Similarly we can put lower bounds on objects whose size can be estimated and which have a visible size in the sky. For example if we can see a galaxy through a telescope its angular 'width' can be measured in radians. If we have a lower bound on the possible size of a galaxy then we can determine a lower bound on its distance from us.

Simply fitting all the observable stars / galaxies into a sphere of radius < 100,000 light years would be imposible unless galaxies are actually no bigger than the solar system and most stars are planet size. Of course there is always the possibility that God created a vast computer screen surrounding the solar system and none of the starts are real at all, but both these posibilities fail Occams razor quite badly.

Originally posted by twhitehead
According to http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/measure_c.html
the speed of light was directly measured on earth as long ago as 1849.
There are many many other ways to measure it and being one of the fundamental constants of the universe it has been verified in many different ways and much of science is based on knowing it. Nu ...[text shortened]... Over the course of about 4 posts you keep implying something is wrong but wont say exactly what.

I'm going to have to go over this some more, but I now have
doubts about what is believed to be the speed of light.

1849 was light actually measured, and with what? How fast they
thought it was going? We are talking about speed here, reaction
time is everything if he or we are off ever so slightly the
measurement of light could be off as much as a ~billion times or
more or less! I also thought it odd that they brought up atomic clocks
while discussiong means of measurement, since clocks are for
tracking time not a means of taking measurements. How fast is the
reaction time of any device matters, sending and recieving signals
isn't a matter of hitting a stop watch! If the measuring of the speed of
light is nothing more than a calculation the whole thing isn't as
factual as you seem to think it is.
Kelly

Originally posted by DoctorScribbles
ROFL, really, you think the universe was created 7K years ago? I don't, so I don't subject my conclusions to being consistent with that premise.

[b]I am giving you light is constant and that you are getting the speed
of light correct, it is just what you think it is, but all of that does
not mean that you know the age!

This is purely sk ...[text shortened]... neither of (1) or (2) hold. Can you give me any non-skeptical argument that they do hold?[/b]

ROFL, really, you think the universe was created 7K years ago? I don't, so I don't subject my conclusions to being consistent with that premise.

I know if you believe the universe is billions of years old, you’d
have to reject anything that goes against that belief. Even if you
were given an actuate way of measuring the age of something now
that showed the universe to be much younger or older you are so
convinced that you know the age, you'd reject it since it didn't line
up with the measurements that agree with your beliefs.
Kelly

Originally posted by KellyJay


I know if you believe the universe is billions of years old, you’d
have to reject anything that goes against that belief. Even if you
were given an actuate way of measuring the age of something now
that showed the universe to be much younger or older you are so
convinced that you know the age, you'd reject it since it didn't line
up with the measurements that agree with your beliefs.
Kelly

Both of your statements are false. Therein lies your confusion about science being a faith.

I'm willing to evaluate any new evidence concerning the age of the universe, and I'm willing to revise my beliefs in light of it. I have no emotional, social or permanent commitment to my scientific beliefs. They are nothing more than a reflection of the weight of the evidence I have considered. The entirety of their value to me lies in the extent to which they accurately reflect the available information about reality. I have no further investment in maintaining them, and no motive to maintain them against the weight of new evidence. In fact, I have every motive to revise them in the face of new evidence.

The only missing ingredient for me to change my belief about the age of the universe is a quantity of evidence that the earth is only 7k years old, sufficient to outweigh the evidence that it is billions of years old.

Provide enough such evidence to tip the scales, and my belief will naturally follow.

Originally posted by Nemesio
Scott,

Could you please explain how we know something is 50k light years away? I think this is the
stumbling block. That is (and I do not know, otherwise I would offer it), how do we know that
the light that reaches us is 50k years old and not 5k years, say?

Nemesio

Imagine a circular island of radius 10 miles, with a golf cart factory at the center.

Suppose upon arriving at this island, you observe a golf cart at the edge of the island.

You hop in, drive it about, and note that it only moves at the speed of 1 mile per hour.

Figure out a lower bound on the age of the golf cart.

If it was created at the factory on the island, it had to travel at least ten miles to have arrived at the edge of the island. Further, it made this trip going at most 1 mile per hour, so the cart in that case is at least ten hours old. This is nothing more than an algebraic manipulation of rate * time = distance, where rate and distance have been measured, and time is unknown.

Seeing the factory, you have evidence the cart was created there. Maybe it bears the same logo as the factory. Now, it's possible that an hour ago a boat from the ocean dropped it off, after creating it at its on-board factory two hours ago, but this would be pure fantasy as you see no evidence to suggest that explanation.

So, unless you're willing to entertain a skeptical explantion of a younger cart, you conclude based on the evidence that it is at least 10 hours old.

Light is completely analogous to the golf cart, having a constant speed.
A star is completely anaologous to the golf cart factory, as photons are emitted from the star, and the distance to stars can be measured via independment means, and sonhouse and twhitehead have described a few methods for doing this.
The observer at the edge of the island is analogous to observers of starlight on earth.
And the island is analogous to the universe.

Originally posted by DoctorScribbles
Imagine a circular island of radius 10 miles, with a golf cart factory at the center.

Suppose upon arriving at this island, you observe a golf cart at the edge of the island.

You hop in, drive it about, and note that it only moves at the speed of 1 mile per hour.

Figure out a lower bound on the age of the golf cart.

If it was created at t is analogous to observers of starlight on earth.
And the island is analogous to the universe.

Thanks, Doc. What I was confused about was the triangulation used
which sonhouse explained. I was being too geocentric in my thinking.

However, your analogy is very not false 😉 and helpful and I appreciate
it, too.

Nemesio

Originally posted by DoctorScribbles
Imagine a circular island of radius 10 miles, with a golf cart factory at the center.

Suppose upon arriving at this island, you observe a golf cart at the edge of the island.

You hop in, drive it about, and note that it only moves at the speed of 1 mile per hour.

Figure out a lower bound on the age of the golf cart.

If it was created at t is analogous to observers of starlight on earth.
And the island is analogous to the universe.

What if you found a book that said it had been made on a boat? The book, of course, being analogous to the Bible.

Originally posted by AThousandYoung
What if you found a book that said it had been made on a boat? The book, of course, being analogous to the Bible.

Then you'd need a forum to debate its evidentiary weight, separate and distinct from a forum about all other island issues.

Originally posted by Nemesio
Scott,

Could you please explain how we know something is 50k light years away? I think this is the
stumbling block. That is (and I do not know, otherwise I would offer it), how do we know that
the light that reaches us is 50k years old and not 5k years, say?

Nemesio

First is parallax:
http://www.windows.ucar.edu/tour/link=/kids_space/star_dist.html&edu=high

Then using data we gain from the 1000 or so closer stars, we measure the brightness of known star types and apply the law of inverse squares to obtain the distance.

http://www.noao.edu/outreach/nop/nophigh/steve13.html