Recent content by Sentosa

I did some research on this. Two atoms of deuterium (total of 2 protons, 2 neutrons, and 2 electrons) weights 4.028 u. One atom of helium-4 (total of 2 protons, 2 neutrons, and 2 electrons) weighs 4.003 u. What exactly causes this? Does the helium atom have less energy, which causes it to have...

In his book https://www.amazon.com/dp/0385477058/?tag=pfamazon01-20, Michio Kaku is discussing hydrogen fusion and states that, "the protons in hydrogen weigh more than the protons in helium". Is this correct? I understand that atoms and nuclei will weigh different amounts, but I thought a...

There's a section in my astronomy book on relativity. The image shows a train traveling at a slow speed and a second image of the train approaching the speed of light. The text says the second train is length contracted, but only in the horizontal direction. In the vertical direction the train...

I just finishedOn the Origin of Species. It seems Darwin is saying that characteristics that make it less likely for an organism to survive will drop out over time. But other scientists tell me that cancer has a genetic link, that suicide has a genetic predisposition, etc. Many diseases have...

Sorry to resurrect my own thread, but I've been thinking about this issue some more. The great paradox in this, it seems to me, is that the key to understanding the invariance of the speed of light is that you have to understand the nature, not of light, but of space and time. It is the...

My physics education was in classical mechanics. More recently I have read Relativity: A Very Short Introduction. I understand the relativity of space and time, although I need to learn more about the relativity of simultaneity. Is it possible that light does in fact travel at different speeds...

I'm not familiar with Maxwell's equations. I understand velocity vectors in classical mechanics, which apparently don't apply in relativity. So why does light behave differently, from say, a tennis ball thrown from a moving bicycle?

I'm trying to understand why the speed of light is the same for all observers. I have found different answers on-line. This page claims that it relates to time dilation. But consider the following thought experiment: two ships flying at 98% c. Ship A is moving toward the sun, and ship B is...