10-03-2020, 08:42 PM

I must be expressing this badly...

Newton could not possibly have had the remotest beginnings of this in his model.

First, E=mc2 was not known. So he had no reason to even suspect that energy had mass. He was familiar with light and knew that it transmitted energy - heat for example. But missing the idea that energy has mass means he could not possibly have even attempted to calculate how much mass the universe had in terms that include the mass-energy of the electromagnetic radiation.

As Newton understood gravity it was a simple force. Proportional to the sum of masses and inversely proportional to the separating distance. That is not a formulation that allows energy to be expressed as gravity, thus even if you're wise to E=mc2, Newtonian gravity is massless.

I'm not talking about Newton's gravity. I'm talking about Einstein's.

Specifically, about gravity waves. In the same way you can take a static force like magnetism and make it oscillate, creating electromagnetic energy, black hole mergers take a static force like gravity and make it oscillate creating gravity-wave energy.

A static force doesn't have energy, and therefore the force itself doesn't have mass. Gravity waves are different, because gravity waves do have energy. And since Einstein worked out E=mc2, we know that means they also have mass.

And so the mass of the universe includes the energy expressed as gravity waves, in exactly the same way it includes the energy expressed as light waves.

Newton could not possibly have had the remotest beginnings of this in his model.

First, E=mc2 was not known. So he had no reason to even suspect that energy had mass. He was familiar with light and knew that it transmitted energy - heat for example. But missing the idea that energy has mass means he could not possibly have even attempted to calculate how much mass the universe had in terms that include the mass-energy of the electromagnetic radiation.

As Newton understood gravity it was a simple force. Proportional to the sum of masses and inversely proportional to the separating distance. That is not a formulation that allows energy to be expressed as gravity, thus even if you're wise to E=mc2, Newtonian gravity is massless.

I'm not talking about Newton's gravity. I'm talking about Einstein's.

Specifically, about gravity waves. In the same way you can take a static force like magnetism and make it oscillate, creating electromagnetic energy, black hole mergers take a static force like gravity and make it oscillate creating gravity-wave energy.

A static force doesn't have energy, and therefore the force itself doesn't have mass. Gravity waves are different, because gravity waves do have energy. And since Einstein worked out E=mc2, we know that means they also have mass.

And so the mass of the universe includes the energy expressed as gravity waves, in exactly the same way it includes the energy expressed as light waves.