verification of age of earth

[imported_Rick]

I have a question. As you know there are religious persons/organizations who
believe the Earth/life is only 6,000 years old +/-. When questioned they say the method of measuring age is flawed , they give many examples and they don't believe it. My question to them is "do you believe in the speed of light?" because that seems to be an unchallenged way to measure time and I assume it could also be used to verify the age of the Earth/solar system other than carbon dating or whatever method is being used?? Related to this is it possible the earth could only support life starting at 6000 years ago?

Am i wrong about this? Can you clarify this connection for me, if there is
one?

Thanks

[Tim Thompson]

There is no way that I know of to use the speed of light by itself, to derive an age for Earth. Of course, it is involved in the physics of radioactive decay, which is used to derive an age for rocks, and infer an age for Earth from the ages of rocks. Then again, do remember that many young Earth creationists do not believe that the speed of light is constant either.

Anyone who does not accept radiometric dating, will not accept any argument that you give them. You make the mistake of thinking that it is actually possible to change the minds of people whose thinking is dominated by prejudice, rather then reason. The arguments of young Earth creationists are worse than bad, and should be treated accordingly. The mainstream arguments for the age of Earth are sound & solid.


Age of the Earth FAQs (http://www.talkorigins.org/origins/faqs-youngearth.html) from the Talk.Origins Archive (http://www.talkorigins.org/)

[imported_Rick]

Thanks for not slamming me too hard. My first time on the site and first post too. Are there better topical areas for some "basic, first and perhaps trivial" questions ?

[antoniseb]

Thanks for not slamming me too hard. My first time on the site and first post too. Are there better topical areas for some "basic, first and perhaps trivial" questions ?

Really, if it is about astronomy and/or spaceflight, any question is fine. Questions that touch on topics of a religious nature will mostly get skirted, as we can't discuss them easily within the rules of this forum. Likewise with politics, or personalities. Keep it clean, as school librarians read the forum.

[Ronald Brak]

I suppose you could always take them to the beach near my place. We have a cliff with something like 20,000 sedimentary layers, which were formed at the rate of one per year. But I don't fancy your chances. I tried to explain to a non nutty lit major how the layers were formed and he didn't believe me. "You're telling me rocks can have layers like a tree has rings? You're pulling my leg!"

[davidlpf]

I think in talk.origins there is an articles about theory about the somebody who thinks the spped of light varied throughout time.

[TheThorn]

There's one neat astronomical case study that demolishes the idea that the speed of light was faster in the past and that's how a 6000 year old universe can look billions of light years across. It's the light echo from SN1987A.

Basically, the light that came here directly from the supernova arrived here at a certain point in time (in 1987). But some light took a longer, indirect route, reflecting off a shell of material that was expelled from that star at an earlier time. That light took longer to get here. By measuring how much longer, we can determine the actual size of that shell of material (assuming a consant speed of light). Knowing it's real size, and how big it looks in the sky, it's simple high-school geometry to figure out how far away it is. Turns out it's about 180,000 light years away. Which means it took that light 180,000 years to get here, which means the universe is at least 180,000 years old.

Oh, but I assumed that the speed of light is a constant. Their counter argument is that light traversed that distance in less than 6,000 years, because it travelled much faster in the past.

But (and here's the great part), if light travelled faster in the past, then the size of that shell of gas is bigger than we thought, because we measured its size based on how long light took to reach it from the supernova, which happened way back in the past when light was travelling fast. Since the shell is bigger than we thought, it is also FARTHER AWAY than we thought. Since the light is slowing down in transit to us from that shell, it actually has to take LONGER than 180,000 years to get here, under their theory.

Their concocted argument might work for other objects, but for light echos in general, it works the wrong way.