F=ma is like W=mg. If weight changes at different temperatures you get two constants on one side of the equation and a variable on the other, disproving this equation. Secondly, say you weigh a sample at 25degC. To find mass of sample you divide weight by gravity and from this you find density and allocate masses to all subatomic particles and astronomical objects. What would happen if you weighed your sample at a different temperature ? You would get completely different masses. Over the past few years I contacted many scientists, universities, journals and societies to do the experiment. Some said weight does NOT change at different temperatures (without experiments to support their claim) and others said weight changes is not a significant problem to physics. Most just did not reply at all. I posted this thread with a hope someone out there will do this most important of experiments.