Evolution: Why is the Earth old?

Question

I need to have evidence that supports the idea that the earth is really, really old. I mean like 4 billion years old. The only thing I can think of is carbon dating and fossils. Got any ideas?

Answer 1

The age of the earth is based on a series of of assumptions based on observations.

There are many, sadly so, who believe that the earth is less than 10,000 years old. The reason they believe that is because they were told that by the generation before, who were told that by the n-2 generation etc...back to the creation myth of a primitive culture. That's it. Oral to written history made up by humans who had no idea of how the universe works.

There is another group of people, those with more education and training in science and math, who hold that the earth is much older. They believe that the solar nebula collapsed and formed our sun and companion planets about 5 billion years ago. The earth's crust cooled about 4.5 billion years ago. The evidence for that comes from observing nature.

A fairly simple concept that tells you that the earth is old is looking at erosion. Water carves into rock and soil, rivers make valleys and gorges. That doesn't happen overnight. If we assume that the rate of erosion in the past is similar to what we observe today, then some canyons must be much older than 10000 years. Small mountains and hills could have started out as the tall mountain ranges of the present so that process must have taken millions of years.

There are other ways to gauge the age of materials that requires more math. We have observed that unstable isotopes of elements will decay into other isotopes or elements. The rate of decay is unique to each isotope and can be measured with precision and accuracy. Carbon 14 dating is the isotope that people hear about the most. Its half life though is relatively short (~5000 years) so it is accurate to only a couple 100,000 years back.

Other isotopes have much longer half lives. U238, for example, has a half life of 4.5 billion years. K40 has a half life of 1.3 billion years. It is a good thing that the earth is so old, because we've gone through 3 half lives of K40. Otherwise, we'd be exposed to 8 times the background radiation in our bodies from this essential mineral. (The "Good Book" doesn't mention this.)

More background is required, such as astronomy and physics to figure out how stars form, live and die. There is a lot of math involved to figure out where stars get the energy to shine and avoid gravitational collapse. But, all of the equations work out and they are self consistent. We can measure the energy output of stars and the gravitational force that must be balanced. We can calculate the energy release by fusion. We can calculate the temperature and density required for fusion to occur. etc. etc. etc. Lots of math that all work out. (Not that much math in holy writings. The only answer seems to be that the gods did it.)

If you follow all that, you would know that the elements heavier than iron are all formed by neutron capture during supernovas (has to do with the nucleon binding energy). The stellar nebula is composed of lumps of these elements that eventually collapses and forms another star and planets. So, here is an assumption that is made. If we can measure the half-lifes of isotopes today, the half-lifes should be the same in the past, even billions of years in the past. If we find a rock with grains of K40 and Ar40, we know that K40 decays to Ar40. We know that the grains were originally formed as K40 and not a mixture with Ar40 (Argon 40 is a gas) so that any Ar40 that is present must be decay products of K40. Some more math and because the half life is so long and potassium is so abundant in the earth's crust means that the K40/Ar40 is able to date rocks that formed billions of years ago. The only alternative explanation given by the religious to explain how the earth can still be young in the face of radio-isotopic data is that their omnipotent deity is perverse and sadistic and chose to make the universe in this state as a test of faith.

You don't use fossils to date rocks. You use rocks to date fossils.

So you can now see why so many people believe that the earth is young while far fewer know how old the earth is. That's because out of all the billions of people on this planet, only an elite few have the freedom, resources and opportunity to get the education and training required to know and understand this. What is really sad is that there are so many with the freedom, resources and opportunity but choose to remain ignorant instead.

Answer 2

Carbon dating is not suitable for determining the age of the Earth, it is only really suitable for very 'recent' history such as archaeological artifacts.
We have been able to accurately determine the age of the Earth because of the discovery of radioactivity. You can tell how old a rock (and therefore any fossils in it) is by analysing the isotopes within the rock. With a knowledge of radioactive decay, and the half-lifes of isotopes, you can put a very accurate age on rocks.

May I suggest that you do some research on Lord Kelvin and Earnest Rutherford, who were involved in the scientific debate about the age of the Earth at the turn of the twentieth century. They are two of the most important players in the subject.

Answer 3

The current calculation is that the Earth is 4.56 billion years old. The earth formed as a gathering of rock and dust which then compressed grew hot and fiery and formed the planet. It was then hit by another planet throwing off a large chunk to form our moon! As it cooled tectonic plates formed which grow from what is called a spreading ridge in the middle of the oceans and then sink back into the molten core at subduction zones. So the rock is constantly being recycled. Earth is made up of several layers. The crust, extends to a depth of about 40 kilometers (25 miles). Below the crust is the mantle area, which continues to roughly halfway to the center of Earth. The mantle is the thick layer of silicate rock surrounding the dense, iron-nickel core, and it is subdivided into the upper and lower mantle, extending to a depth of about 2,900 km (1,800 miles). The outer core is beneath that and extends to 5,150 km (3,200 mi) and the inner core to about 6,400 km (4,000 mi). Oceanic crust makes up two-thirds of the Earth’s surface and is the youngest rock. It is made of igneous rock and formed at mid-ocean ridges, the largest volcanic system on our planet, from melting in the mantle. Eventually, oceanic crust is consumed at major earthquake-generating deep-sea trenches. The oldest rocks are found on the continents. Carbon dating works because certain chemical elements have more than one type of atom. Different atoms of the same element are called isotopes. Carbon has three main isotopes. They are carbon-12, carbon-13 and carbon-14. Carbon-12 makes up 99% of an atom, carbon-13 makes up 1% and carbon-14 - makes up 1 part per million. Carbon-14 is radioactive and it is this radioactivity which is used to measure age. Radioactive atoms decay into stable atoms by a simple mathematical process. Half of the available atoms will change in a given period of time, known as the half-life. For instance, if 1000 atoms in the year 2000 had a half-life of ten years, then in 2010 there would be 500 left. In 2020, there would be 250 left, and in 2030 there would be 125 left. By counting how many carbon-14 atoms in any object with carbon in it, we can work out how old the object is - or how long ago it died. So we only have to know two things, the half-life of carbon-14 and how many carbon-14 atoms the object had before it died. The half-life of carbon-14 is 5,730 years. However knowing how many carbon-14 atoms something had before it died can only be guessed at. The assumption is that the proportion of carbon-14 in any living organism is constant. It can be deduced then that today's readings would be the same as those many years ago

Answer 4

So far scientists have not found a way to determine the exact age of the Earth directly from Earth rocks because Earth's oldest rocks have been recycled and destroyed by the process of plate tectonics. If there are any of Earth's primordial rocks left in their original state, they have not yet been found. Nevertheless, scientists have been able to determine the probable age of the Solar System and to calculate an age for the Earth by assuming that the Earth and the rest of the solid bodies in the Solar System formed at the same time and are, therefore, of the same age.

The ages of Earth and Moon rocks and of meteorites are measured by the decay of long-lived radioactive isotopes of elements that occur naturally in rocks and minerals and that decay with half lives of 700 million to more than 100 billion years to stable isotopes of other elements. These dating techniques, which are firmly grounded in physics and are known collectively as radiometric dating, are used to measure the last time that the rock being dated was either melted or disturbed sufficiently to rehomogenize its radioactive elements.

Ancient rocks exceeding 3.5 billion years in age are found on all of Earth's continents. The oldest rocks on Earth found so far are the Acasta Gneisses in northwestern Canada near Great Slave Lake (4.03 Ga) and the Isua Supracrustal rocks in West Greenland (3.7 to 3.8 Ga), but well-studied rocks nearly as old are also found in the Minnesota River Valley and northern Michigan (3.5-3.7 billion years), in Swaziland (3.4-3.5 billion years), and in Western Australia (3.4-3.6 billion years). [See Editor's Note.] These ancient rocks have been dated by a number of radiometric dating methods and the consistency of the results give scientists confidence that the ages are correct to within a few percent. An interesting feature of these ancient rocks is that they are not from any sort of "primordial crust" but are lava flows and sediments deposited in shallow water, an indication that Earth history began well before these rocks were deposited. In Western Australia, single zircon crystals found in younger sedimentary rocks have radiometric ages of as much as 4.3 billion years, making these tiny crystals the oldest materials to be found on Earth so far. The source rocks for these zircon crystals have not yet been found. The ages measured for Earth's oldest rocks and oldest crystals show that the Earth is at least 4.3 billion years in age but do not reveal the exact age of Earth's formation.

Answer 5

And the universe is 14 billion years old. Yes, evidence is the time it takes light from previous exploding stars to reach us. The conclusion that the universe is 14 billion years old is from the fact that light from an exploding star (14 billion years ago) is reaching us only now. That means it took the light 14 billions years to get to us. Amazing, eh?

Answer 6

carbon dating is only for living things and is only really useful for moderately recent things
..potassium/argon dating is used for much older rock, which I think from memory helps date a lot of igneous rock...

I am not sure if its completly relevant but I tihnk things like erosion of rock in what are considered the most ancient places like greenland and Australia can also help

Answer 7

the oldest rocks that build up the earth is 3.8 billion years old

Answer 8

How about carbon dating and fossils?

Answer 9

Check this out...

http://answers.yahoo.com/question/index;_ylt=AvVAL_OF8hggn6yp7OtfiCUjzKIX?qid=1006032003790

Answer 10

the earth is only 6000 to about 8000 years old, dont believe evolution, if evolution were true then why have'nt we evolved any more, we were made by a creator God! Have you ever seen an explosion (big bang) make anything look as beautiful as our universe, or be round like our planet and other planets, NO! That's because it had a designer.