- #1

Lok

- 601

- 24

- TL;DR Summary
- A simple physics problem to understand the nature of mass by falling celestial bodies.

Hi PF, long time no see. Hope you are all well.

Recently I have come into a mental conundrum of a cosmological physical nature.

After doing some napkin calculations about the energy of celestial bodies and transforming them into mass via E=mc^2 I've found that said energy is by no means small.

Therefore I would like to post a though experiment.

I treated it classically and found that the Sun would attain enough kinetic energy to equal ~24% of it's mass, and while I am sure relativistic effects play a massive part, 24% is hardly something to ignore or cancel out.

Basically I assume that the box in the initial state should weigh exactly as much as the final state as measured via lensing from a distant enough observer, yet the final state has 24% more of a solar mass. Was the final state mass hidden in the initial state as potential energy? How?

Data used:

mSun=1.9885e+30 kg

MSagA*=8.544e+36 kg

R Sag A*=2.59e+10 m

Energy of Sun close to Sag A*=4.378e+46 J

excess mass= 4.86e+29 kg

Classical energy formula of U=-G*(M*m)/R

I am sorry if this is similar to other threads and if someone could help me understand this better I would be very grateful.

Cheers!

Recently I have come into a mental conundrum of a cosmological physical nature.

After doing some napkin calculations about the energy of celestial bodies and transforming them into mass via E=mc^2 I've found that said energy is by no means small.

Therefore I would like to post a though experiment.

**"Given a large box with our Sun and Sagitarius A* at their respective distance one from the other, with the tangential speed of the Sun equal to zero and free falling towards Sag A*, how much does that box weigh? And how much would that box weigh when the Sun falls via gravity close enough to touch Sag A*?"**I treated it classically and found that the Sun would attain enough kinetic energy to equal ~24% of it's mass, and while I am sure relativistic effects play a massive part, 24% is hardly something to ignore or cancel out.

Basically I assume that the box in the initial state should weigh exactly as much as the final state as measured via lensing from a distant enough observer, yet the final state has 24% more of a solar mass. Was the final state mass hidden in the initial state as potential energy? How?

Data used:

mSun=1.9885e+30 kg

MSagA*=8.544e+36 kg

R Sag A*=2.59e+10 m

Energy of Sun close to Sag A*=4.378e+46 J

excess mass= 4.86e+29 kg

Classical energy formula of U=-G*(M*m)/R

I am sorry if this is similar to other threads and if someone could help me understand this better I would be very grateful.

Cheers!