How can Scientist tell how old the world is??????

Question

When everything that they use to determine this is modern man made things???

Answer 1

There is a very good description at the link I've included. Essentially, the estimated age of the planet is really a lower limit established by testing of various isotopes all over the planet. Conveniently, they all point to roughly the same age, approximately 4.5 billion years old.

Answer 2

Scientists primarily use radiometric dating, especially of uranium to lead in the mineral zircon both in rocks formed on Earth and in meteorites. Uranium decays to lead at a predictable rate, and by measuring the proportion of lead to uranium, scientists can determine how old that rock is. The oldest rocks found on Earth are between 3 and 4 billion years old. Because in Earth's early years, rocks were recycled very quickly through a process similar to modern tectonics, samples from that time have not survived to today. We therefore expect Earth to be old than the oldest rock sample on Earth. Meteorites are rocks from the time of the formation of the planets. By dating meteorites and comparing them to the oldest rocks on Earth, scientist have determined that the Earth is a little over 4.5 billion years old.

You can check out this Wikipedia article, which is pretty good:
http://en.wikipedia.org/wiki/Earth_Age

Answer 3

Cardinals fan,

Scientists may use modern equipment in order to get information, but they are making the measurements on natural materials that have answers about the earth locked away inside them. There is no contradiction in using modern technology to answer basic questions about processes that took place long ago.

The main way that scientists know the age of the earth is from measurements of radioactive isotopes. Certain isotopes will decay into another isotope, and since the rates of decay of these istopes have been well documented by experiment and verified by quantum theory, measuring the amounts of both the parent and daughter isotope will provide an age for the rock in which they're measured. Rocks in the earth have been discovered that date to about 4.2 billion years, but various corrections and other details will push the date of the formation of the earth itself back to about 4.6 billion years.

Another way is by measuring heat flow inside the earth. Since we know the chemical makeup of the earth, and know what temperature would be required for the earth to start solidifying, calculations of heat dissipation can also come up with an age of the earth. These estimates also give about 4.6 billion years. There are a number of other methods that I don't know as much about, but all of them yield numbers close to 4.6 billion years. They all rely on basic laws of physics and chemistry, and they all corroborate each other, so there is no doubt in the scientific community about the age of the earth.

Answer 4

One of the ways that can determine the age of fossils is that most living creatures contain a very small amount of a radioactive isotope of carbon (Carbon 14; normal carbon is Carbon-12). That amount is refreshed through normal "life" processes, but as soon as the creature dies, the amount of Carbon 14 decreases at a predictable rate. So if you examine old bones, you can measure the amount of carbon 14 and work backwards to when the creature died. That's how they know some dinosaur bones are 65 million years old.

There are other ways that are less well known but equally reliable over different date ranges.

The oldest fossils date to the so called Cambrian period, so we know the Earth is older than that (I forget, but I think the number is something like 2.5 billion years to the start of the Cambrian period). We also know a little bit about the lifecycle of stars (around which planets generally appear) and how long it takes for stars to age, based on the amount of certain elements that show up in their spectra. Google Hertzsprung-Russell and a lot will show up.

So we know based on the fact that our sun is fits into the HR class of G2, that it can't be older or younger than a certain age, which just HAPPENS to fit well with the age of the Earth predicted by other means. All estimates based on known physical processes seem to point to the same age, roughly 4.5 billion years, for the age of the Earth.

Occasionally, some new fact or discovery pops up that adjusts that date, but most of the information from physics, cosmology, geology and archaeology converge on the same set of numbers, and in science, when everything seems to point to the same number or range of numbers, we say we are pretty confident that the theory is supported by the facts.

Generally, it's harder to prove a theory true than it is to prove it's false... but you can get yourself killed trying to disprove the theory of Gravity.

Hope this helps.

Answer 5

Radiocarbon dating is not used for measuring the age of fossils. Fossils are stone and you need carbon to be present to use carbon dating. The method cannot be used on stuff older than 50-60,000 years as the half life of carbon 14 is quite short. There are, however, many other radioactive isotopes with longer half lives that are used to date rocks. The consensus of all of them is that the earth is about 4.6 to 4.7billion years old.

Answer 6

hey check reference works written by other earlieer scientists.

Answer 7

I.... don't.... know........
Your going to have to ask a scientist that or someone else, sorry.

Answer 8

they don't KNOW, they just estimate 4.5 billion years. why? they date rocks.

Answer 9

idk im not a freakin scientist.lol. good luck . sorry. justine.