Some of the most commonly used radiometric schemes are [Dalrymple1991, pg. 55]: Each method has its own particular range of applicability, which derives from the half-life of the particular radioactive decay involved.Uranium-thorium dating, for instance, can be used to date specimens up to about 500,000 years old (since the half-life of the U-Th decay is 75,000 years), but Rubidium-Strontium dating can be used to date specimens billions of years old (since the half-life of the Rb-Sr decay is 48.8 billion years).Quantum mechanics is one of two cornerstones of modern physics (the other is general relativity), and has been precisely confirmed in thousands of very exacting experiments.
In a fusion reaction, massive amounts of energy are emitted.
Keep in mind that during this process, not all of the mass is conserved.
The 'heavier' atom that is produced is actually lighter than the two individual pieces, which means that mass is lost.
The following is a brief technical description of how scientists determine dates with radiometric schemes.
This section may be omitted if readers do not wish to follow the math (although the math used here is nothing beyond what is typically taught in a good high-school math analysis class).