The Age of Things

INTRODUCTION

There are many ways to find the age of things. Six non-atomic methods are named first:

• Population statistics.
• Tree ring counting.
• Magnetic field analysis.
• Salt-in-sea approach.
• Helium gas in atmosphere.
• Direct observation or record keeping.

There are four methods used in atomic physics and chemistry:

• Radiometric dating:

  • potassium-argon
  • uranium-lead
  • rubidium-strontium
  • carbon-14

There are also methods that take us beyond the earth:

• Helium content of meteorites.
• The recurrence of long term comets.
• The existence of distinct planet rings, etc.

THE PHYSICS OF RADIOACTIVITY
Half Life

The term HALF LIFE refers to a certain period of time. In relation to radioactivity, the HALF LIFE of a certain radioactive element refers to the time it takes for the mass of the decaying element to reduce by ½. Or one could say that the HALF LIFE of a certain radioactive element is the time it takes for the number of nuclear disintegrations per second to reduce by ½.

The half life of some elements are:

• Tritium ............ 12.3 yrs
• ¹⁴Carbon ........ 5730 yrs
• ⁴⁰Potassium.... 1300 my (million years)
• ²³⁸Uranium .... 4510 my.

Five conditions must be met for the radioactive clocks to work.

1. Decay must occur at a measurable speed.
2. Amounts of radioactive materials must be measurable.
3. The ½ life must be determined and be constant throughout time.
4. Initial amount of element and offspring must be known.
5. No parent or offspring must be added or taken away while the clock is running.

Problems may occur because there is evidence that the ½ life and therefore the rate of decay can be changed by a variation in;

• pressure,
• temperature,
• electrical potential, or
• chemical state of the radioactive material.

If any one or combination of the above factors would change, then the tick, tick, tick rate of the clock would change and its ability to keep accurate time would be hampered.

RADIOACTIVE DATING METHODS
Uranium-Thorium-Lead Method

This method was first used in 1907. When the substance that is decaying in this method is observed, the by-products are lead and helium. It is impossible to say if the lead is by-product lead or alien lead. To measure the by-product helium, is also difficult because it escapes into the atmosphere from the rocks, rises and goes into outer space. Besides that, uranium leaches out of the rocks and floats out into the seas via rivers (50,000 tons/year). (See Creation ex Nihilo 20(3) June-August 1998, p. 19.)

Potassium-Argon Method

Radio active ⁴⁰Potassium changes into ⁴⁰Argon gas (11%) and ⁴⁰Calcium (89%). We run into the same problems as in the ²³⁸Uranium^-206Pb method. The biggest problem is that the amount of ⁴⁰Argon is 100 times too high even if the earth is 4.5 billion years old. Therefore there must be large amounts of the ⁴⁰Argon that came from outside sources or there must have been huge amounts present in the beginning. Argon gas comes up from the earth's interior under great pressure and penetrates the surface rocks in high concentration which are the very rocks measured to determine an age for the earth. Also the ⁴⁰Potassium leaches out of rocks at a high rate. After 4.5 hours of running distilled water over a meteorite, it's ⁴⁰Potassium content was reduced by 80%.

Rubidium-Strontium Method

The ½ life of ⁸⁷Rubidium is thought to be 49,900 million years. The earth's crust contains 10 times more ⁸⁷Strontium than one would expect to find if it had all come from ⁸⁷Rubidium. Numbers are then shuffled so as to make the results compatible with other methods. ⁸⁷Rubidium leaches out of rock as well. ⁸⁷Strontium can disappear from rock by ion-exchange. No matter what corrections are applied, one never knows if the corrections are correct.

As can be seen from these analyses, it always seems as if the true answer to these dating methods is very elusive. It is similar to trying to catch hold of a fish in the water with bare hands.

¹⁴Carbon Dating Method

This method was introduced in 1948 to date organic material of recent origin. ¹⁴Nitrogen changes into ¹⁴Carbon due to bombardment of ¹⁴Nitrogen by cosmic rays. ¹⁴Carbon then combines with O₂ to form ¹⁴CO₂ which plants take in when they breathe in order to form O₂ and organic materials. Humans and plant-eating animals then ingest these ¹⁴C compounds and meat eaters eat the flesh of these animals. Therefore all plants and animals should have about the same concentration of ¹⁴C in their bodies when they die. After that the concentration begins to decrease because there is no further ingestion, but the decay of ¹⁴C continues.

In order for the method to work, 5 assumptions must all be true:

1. The ½ life (5730 y) of ¹⁴C must always be constant,
2. The rate of formation of ¹⁴C must always have been constant,
3. The concentration of ¹²C must always have been constant,
4. The ration of ¹⁴C/¹²C must always have been constant,
5. The rate of formation and decay of ¹⁴C must always have been constant.

None of these assumptions can reasonably be expected to be true. Before Noah's time there may have been a canopy that shielded the earth from cosmic rays. Then there would have been very little ¹⁴C formed so present tests would show an old age.

The magnetic field of the earth is decaying at present (to ½ in 1400 years). This would have protected earth in the past from cosmic rays thus showing a much older age for the earth than it really is.

The rate of formation of ¹⁴C exceeds the rate of decay by 24% today. This maximizes the age of the earth at about 30,000 years.

Also, samples can easily be contaminated after they die.

CONCLUSION

Because of the 5 assumptions which can each throw off the true age of measured samples, any confidence in the absolute accuracy of radiometric dating is ill founded!

Mr. Rudi Fast, B.A. (honors physics), B.Ed.