On Wed, Feb 26, 2025 at 3:24 PM Brent Meeker <[email protected]> wrote:
*> the reason GR predicts a singularity is that all forces contribute to > mass-energy density and the higher the density the higher the curvature > (that's Einstein's equations). * > *In Newtonian gravity only mass creates gravitational fields but in General Relativity, because E=MC^2, energy also makes a contribution, but that's not all, it makes a difference what sort of energy it is. Both positive pressure and negative pressure (tension) are forms of energy, but they have opposite effects on the gravitational field. Positive pressure increases spacetime curvature and makes gravitational attraction stronger than what you would expect from mass/energy density alone, while negative pressure does the opposite. Negative pressure causes spacetime curvature to be smaller than what you would expect and causes a sort of anti-gravity effect.* *The ACTIVE gravitational mass/energy density is proportional to the gravitational mass density PLUS 3p/c^2. So if the pressure is sufficiently negative then things will start to expand, not contract; and that's why many people think Dark Energy is some sort of negative pressure and is a fundamental property of space.* *John K Clark See what's on my new list at Extropolis <https://groups.google.com/g/extropolis>* ica -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/everything-list/CAJPayv1gp%2B3y7PiyenJFa_%2BTkGDXaCp3h%3DB9fsbJiTMKz3pfkA%40mail.gmail.com.
