<|im_start|>system
You are a helpful AI assistant.<|im_end|>
<|im_start|>user
What's the half life of a helium 6 isotope?<|im_end|>
<|im_start|>assistant
The helium-6 isotope has a half-life of 806.7 ms.<|im_end|>
<|im_start|>user
Can you provide a reference to your number? Also, how accurate is this number?<|im_end|>
<|im_start|>assistant
Sure! [Here's a link to a reference regarding the number I provided above about the helium-6 isotope half-life](https://pubchem.ncbi.nlm.nih.gov/compound/Helium-6-atom#:~:text=Helium%2D6%20atom%20is%20the,half%2Dlife%20of%20806.7%20ms.)

According to the source, the number I provided above should be accurate.<|im_end|>
<|im_start|>user
What element has the highest half life?<|im_end|>
<|im_start|>assistant
Among radioisotopes, Bismuth-209 (209Bi) has the longest known half-life, as long as 2.01 * 10^19 years. However, if we take all elements into consideration, Hydrogen-1 (1H) with a nucleus containing only a single proton would have the longest half-life, as the current estimate of the half-life of a proton is at least 1.67×10^34 years and no proton decay has ever been observed.<|im_end|>