light years

[devotee]

"...light from the most distant objects currently visible in telescopes may take several billion years to reach us...therefore give us an image of what the universe looked like billions of years ago." Paul Davies, Other Worlds, p. 54

How can I be confident that the distance travelled "is" several billion light years?

 

[KerrMetric]

How can I be confident that the distance travelled "is" several billion light years?

Because it can be measured is the short answer.

 

[truth above all else]

Because it can be measured is the short answer.

hmm where can i purchase such a yardstick

 

[rmwilliamsll]

hmm where can i purchase such a yardstick

go to google
use your time as currency

ask for:
parallax

as in:
http://www.noao.edu/outreach/nop/nophigh/steve9.html

after absorbing this ask for:
redshift
cephid

after that you probably can do it yourself.
best of searching and studying to you....

 

[michabo]

hmm where can i purchase such a yardstick

Do you know what it looks like? Do you know how to read it?

 

[shinbits]

Because it can be measured is the short answer.

Well, that's not really an accurate way to measure how long it's been in existence. By doing that alone, you'd conclude that the sun is only 8.4 minutes old.

Or, consider a flashlight powerful enough to be seen billions of miles away. Suppose I flash that light at the ground, then go backwards billions of miles. Measuring how long the light takes to reach us is not the least bit accurate then, because the light has always been shining at the ground.

There is, of course, doppler red to be considered, but it still leaves the same problem.

 

[michabo]

Well, that's not really an accurate way to measure how long it's been in existence. By doing that alone, you'd conclude that the sun is only 8.4 minutes old.

You'd conclude that the sun is at least 8.4 minutes old. The OP is not talking about the total age of the universe, only how one can conclude certain objects are billions of light years away.

 

[JohnR7]

How can I be confident that the distance travelled "is" several billion light years?

We are told that the universe has been expanding for billions of years. We are expanding with the universe. It is not a question of the light taking that long to get to us, it is a issue of the light showing an event that took place that long ago.

This actually is a important YEC issue. What from one perspective could have taken thousands of years, from another perspective could have taken billions of years. It all depends on your perspective and your vantage point.

 

[random_guy]

hmm where can i purchase such a yardstick

You are aware that we have no yardstick to measure the distance from the Earth to the Sun. Do you accept that estimate that the distance from the Earth to the Sun is [FONT=Trebuchet MS, Arial, Helvetica]150*10^6 km? [/FONT]

 

[shinbits]

You'd conclude that the sun is at least 8.4 minutes old.

Yeah, I thought that was implied, but in debate forums, I need to make sure I'm more specific.

But the rest of what I've posted shows why measuring age with light is inaccurate.

 

[KerrMetric]

Yeah, I thought that was implied, but in debate forums, I need to make sure I'm more specific.

But the rest of what I've posted shows why measuring age with light is inaccurate.

What you posted in the earlier post was pure gibberish.

 

[Lucretius]

Yeah, I thought that was implied, but in debate forums, I need to make sure I'm more specific.

But the rest of what I've posted shows why measuring age with light is inaccurate.

This is incorrect because we know the basic outline of a stars life. We do not therefore conclude the sun is only 8.4 minutes old. We can tell from certain factors present in the sun how long it has been around. The light just tells us how old the image we are currently seeing is. Thus an object who's light took 10 billion years to reach us is not necessarily 10 billion years old. That is just how it looked 10 billion years ago. We can say definitively that it was around 10 billion years ago, but not that it is around today.

 

[Grengor]

What you posted in the earlier post was pure gibberish.

Ditto, I did not understand what he was saying at all. Shinbits, please explain in detail.

 

[shinbits]

What you posted in the earlier post was pure gibberish.

Okay.

I'll post the second part of my post. I agree with you what some of you said about the first part. If you disagree with something, explain what you disagree with.

Consider a flashlight powerful enough to be seen billions of miles away. Suppose I flash that light at the ground, then go backwards billions of miles. Measuring how long the light takes to reach us is not the least bit accurate then, because the light has always been shining at the ground.

There is, of course, doppler red to be considered, but it still leaves the same problem.

 

[Grengor]

Okay.

I'll post the second part of my post. I agree with you what some of you said about the first part. If you disagree with something, explain what you disagree with.

Consider a flashlight powerful enough to be seen billions of miles away. Suppose I flash that light at the ground, then go backwards billions of miles. Measuring how long the light takes to reach us is not the least bit accurate then, because the light has always been shining at the ground.

There is, of course, doppler red to be considered, but it still leaves the same problem.

You just reposted basically the same exact thing. You didn't explain anything. I'm not too familiar with doppler red, so I'll reserve my opinion on that, but we're not viewing the light from the flashlight that hits the ground, we're viewing the light that goes toward us. So it doesn't matter, if the flashlight is 10,000 light years away, the light we're viewing is 10000 years old.

You're honestly not making sense. Please, explain, in detail, with references, and actual examples/experiments. You seem to be having problems with analogies.

 

[shinbits]

Well, I wanted to first know what people disagreed with. Then I'll go into more detail.

 

[Hydra009]

What from one perspective could have taken thousands of years, from another perspective could have taken billions of years. It all depends on your perspective and your vantage point.

Exactly. And that's the key truth most people are missing - facts are relative. Scientists say the Earth is billions of years old, that's their belief. I prefer to say that the Earth is about 10,000 years old, and that's my belief. I also like to think that gravity is really 5 m/s^2 at sea level and 2 plus 2 equals 3. The "experts" don't agree, but that's because they don't undertand how facts work.

 

[shinbits]

This is incorrect because we know the basic outline of a stars life. We do not therefore conclude the sun is only 8.4 minutes old. We can tell from certain factors present in the sun how long it has been around..

My point was, that using light alone is not a good indicator of age.

And as far as telling the age of the star, there's no way to tell that a star has been around for billions of years. What we can tell, is how much longer a star will be around for.

 

[Physics_guy]

Okay.

I'll post the second part of my post. I agree with you what some of you said about the first part. If you disagree with something, explain what you disagree with.

Consider a flashlight powerful enough to be seen billions of miles away. Suppose I flash that light at the ground, then go backwards billions of miles. Measuring how long the light takes to reach us is not the least bit accurate then, because the light has always been shining at the ground.

There is, of course, doppler red to be considered, but it still leaves the same problem.

What you are doing is aiming a stream of photons emitted by your flashlight at the earth. When you are right next to the ground the photons you emit hit the ground nearly instanteously, but as you recess, the distance those photons have to travel increases and the amount of time they take to hit the spot on the ground increases. By the time you are many light years away the photon you emit from that flashlight must travel for many years to reach that spot. It is irrelevant that the spot you left on the ground has always been there because you have been shining a continuous stream of photons on it.

Now, realize that we use several techniques to measure the distance between us and distance objects which have varying levels of accuracy, bt are all quite useful and well supported. Once we know how far away the pbject is, we can then say how old the photons from it we are seeing are because we know exactly how fast light travels.

 

[shinbits]

What you are doing is aiming a stream of photons emitted by your flashlight at the earth. When you are right next to the ground the photons you emit hit the ground nearly instanteously, but as you recess, the distance those photons have to travel increases and the amount of time they take to hit the spot on the ground increases. By the time you are many light years away the photon you emit from that flashlight must travel for many years to reach that spot. It is irrelevant that the spot you left on the ground has always been there because you have been shining a continuous stream of photons on it.

Now, realize that we use several techniques to measure the distance between us and distance objects which have varying levels of accuracy, bt are all quite useful and well supported. Once we know how far away the pbject is, we can then say how old the photons from it we are seeing are because we know exactly how fast light travels.

I agree completely that light is a good way to tell how far an object is. But it is not a good tool to measure how old an object is.