light years

[dad]

Wrong again.

Are you actually lying here to put on a show?

That was an example of if we put something in, not some claim of that being some literal program. Are you hyper, and wound too tight?

 

[Dannager]

As illuminating as it sometimes may be, it really depends on what gets put in. What do you think we specify to a computer when working on a stellar problem? We don't rub the monitor, and expect some genie to pop out after we ask, how old and far away ids that star? We put in the distance, based on present light years, and present nuclear decay, perhaps, etc.
If it is an evolutionary set of assumptions underlying the process, we get evolutionary answers. Not rocket science, that.

This is false. We use math. There are no "evolutionary" processes involved. For more information: http://en.wikipedia.org/wiki/Astronomical_distance.

 

[KerrMetric]

Of course it is, and a meaningless one, unless you can do more than assume the past was the same. Even some basic thing like gravity. Imagine if even something as simple as 4 hydrogen atoms being the same weight as one helium atom - if gravity was not here as we know it in the distant past.!!!

It's not an assumption. I am not assuming the past was the same I am measuring it was the same. So unless you descend into the pseudo-solipsism you are stuck with actual measurements contradicting your nonsense.

 

[KerrMetric]

That was an example of if we put something in, not some claim of that being some literal program. Are you hyper, and wound too tight?

I'm just pointing out you use the word assumption in an unfounded manner.

 

[dad]

I'm just pointing out you use the word assumption in an unfounded manner.

No, I don't. There must be assumptions involved in cosmological calculations. You can't deny it, no matter how you try to rephrase it!

 

[dad]

It's not an assumption. I am not assuming the past was the same I am measuring it was the same. ....

You think you are measuring time and the past, but you aren't in the degree you believe. You assume the data represents great time, not measure great time yourself. Be honest.

 

[KerrMetric]

No, I don't. There must be assumptions involved in cosmological calculations. You can't deny it, no matter how you try to rephrase it!

Give me what "must" (your word) be an assumption.

 

[KerrMetric]

You think you are measuring time and the past, but you aren't in the degree you believe. You assume the data represents great time, not measure great time yourself. Be honest.

No I don't. And I am sure my knowledge of this vastly outweighs yours - and that is not an assumption either.

 

[dad]

Give me what "must" (your word) be an assumption.

That should be easy. Name a few things about the stars you think represent old age.

As for your great knowledge, I am impressed, however one dimensional it may be. You know the far corners of the box. Whopee do.

 

[KerrMetric]

That should be easy. Name a few things about the stars you think represent old age.

Stars or cosmology? You have danced between the two in the last few posts.

 

[dad]

Stars or cosmology? You have danced between the two in the last few posts.

Fine, since you're too smug to pick, I will.
The decay of the sun. Will it burn out? Was it decaying a long time? How exactly do you 'know'?

 

[KerrMetric]

Fine, since you're too smug to pick, I will.
The decay of the sun. Will it burn out? Was it decaying a long time? How exactly do you 'know'?

Forget about the real Sun for a second.

If I model a mass of gas of the solar composition and calculate its physical properties and let it evolve in time - using the basic physical laws of thermodynamics, hydrodynamics, statistical mechanics, gravity, atomic and nuclear physics, radiative transfer theory etc etc. then the model will exhibit the observed properties of stars of this mass/composition.

Even without calibration the the model will change over time and exhibit the observed properties of sub-giants and eventually red giants on time scales of (for solar mass) of billions of years. Now since in this example I have not calibrated the model then the ages will be off by perhaps 20% or so the fact is a 20% error on say 12 billion years at the tip of the red giant branch still means out based in physics model gives long ages WITHOUT any assumption.

 

[devotee]

Please Google this. There are many websites with diagrams that explain this better than I can write a sentence or two about it.

Your frequency question makes no sense.

about to google...re. frequency: the further the object the longer the wavelength the redder the light?

 

[KerrMetric]

about to google...re. frequency: the further the object the longer the wavelength the redder the light?

For a regular doppler shift it is the faster the object is moving away the then the greater the red shift.

In cosmology it actually isn't a doppler shift. It is the expansion of the universe that causes the shift. And this is proportional to distance. Though it is not the same functional form as a doppler shift.

 

[devotee]

Because the speed of light in a vacuum is a constant. If we see an object fifty light years away, then it must be at least fifty years old, or else the light wouldn't have had the time to reach us yet. If we see an object fifty thousand light years away, then it must be at least fifty thousand years old.

The Hubble telescope has spotted galaxies twelve billion light years away.

but why am i confident that the object is fifty light years away?

 

[KerrMetric]

but why am i confident that the object is fifty light years away?

Because that close you can measure the object by trigonometry.

 

[Dannager]

but why am i confident that the object is fifty light years away?

Because when something is under 200 light years away you don't even need more advanced methods. You can simply measure position at two different points in earth's orbit of the sun and use 11th-grade trignometry to determine the distance.

 

[devotee]

Because when something is under 200 light years away you don't even need more advanced methods. You can simply measure position at two different points in earth's orbit of the sun and use 11th-grade trignometry to determine the distance.

So I can generalise from the trignomety: if I accept trignometic findings for distance on Earth, I can be confident the same principles apply in space - at least to a certain distance.

As I failed math and sceince at high-school...why do the principles not apply to objects further than 200 light years? Do the angles become meaningless?

 

[KerrMetric]

So I can generalise from the trignomety: if I accept trignometic findings for distance on Earth, I can be confident the same principles apply in space - at least to a certain distance.

As I failed math and sceince at high-school...why do the principles not apply to objects further than 200 light years? Do the angles become meaningless?

Dannager is a little out of date. Trig can work directly out to about 1500 light years or so. The angles then become too small.

However if you wait about 5 years from now there is a satellite mission called Gaia to be launched that will increase this to probably about 30,000 light years - 60,000 light years.

 

[Dannager]

So I can generalise from the trignomety: if I accept trignometic findings for distance on Earth, I can be confident the same principles apply in space - at least to a certain distance.

Exactly.

As I failed math and sceince at high-school...why do the principles not apply to objects further than 200 light years? Do the angles become meaningless?

That's precisely it. Sounds like you didn't come out of your math courses too bad off if you're able to pick that up. Were our instruments more precise we could use measurements that allow us to tell distances through trignometry of greater than 200 light years, but for right now that's about as far as we can get without involving more advanced formulae. The angles become ridiculously minute.