# Distortion of space and time

What will happen to the distorted space and time around a mass when it is converted into energy? Will it back to its original configuration (0 gravity)? Or space time oscillates? Or anything else

• According to relativity theory, mass cannot really convert to energy. The well-known formula $E = mc^2$ says that mass and energy are the same thing. – md2perpe Sep 26 '18 at 14:25
• So you want to say that energy also distort space and time. – Sourabh Sep 26 '18 at 14:30
• Correct. In the Einstein field equation the tensor $T_{\mu\nu}$ contains the energy and momentum density which might have its origin not only in matter ("mass") but also in other types of energy. – md2perpe Sep 26 '18 at 14:34
• There is no simple answer, because quantum mechanics is not compatible with general relativity. It depends on the details. If the released energy is perfectly contained, then almost nothing may happen, because the gravitational equations include the stress-energy tensor. However, if you convert a planet to a burst of light, you would need to know the gravitational field of each photon. The gravity of a photon is not static, it is a gravitational wave emitted from the source. The full treatment is a subject of quantum gravity that has not been developed. So there is no simple answer. – safesphere Sep 26 '18 at 15:59
• Hint: The source for gravity is energy rather than mass. – Qmechanic Sep 27 '18 at 8:33

To answer this, lets use a single atom as an example. Essentially, the energy contained in that atom (bonds between the sub-atomic particles in the atoms nucleus) radiates away at the speed of light away when released, mostly in the form of Gamma radiation. the gravitational field would radiate out in exactly the same way, since mass is essentially energy stored in the bonds between the particles that make up the nucleus of the atom.

This means the mass really was just stored energy, which is released when those bonds break. It would cause a ripple in the gravitational field. Of course, there being nothing were the atom used to be, there's nothing to attract anything there.

• What is the meaning of "gravitational ripple" here? A gravitational wave ?? – Sourabh Sep 26 '18 at 13:37
• Basically like a wave without a trough behind it, barring any oscillations due to field interactions. imagine adding a drop of water to the middle of a lake - the surface height would increase slightly, propagating at the speed of the wave. – Russell King Sep 26 '18 at 13:46
• So an atomic bomb can produce a gravitational wave.?? – Sourabh Sep 26 '18 at 13:47

There are several ways to convert mass into energy. The mass of a star e.g. decreases slowly due to nuclear fusion processes. In this case energy is radiated away which corresponds to a slight decrease of mass. As the mass of the star remains spherical symmetric during this process, so does its gravitational field and thus the spacetime around the star will not be distorted.

The complete conversion of mass into energy is possible by particle-antiparticle annihilation. Perform this process in a ideal box (withstanding the heat) the weight of the box will not change and neither does the spacetime.

Distortions of spacetime are caused by asymmetric processes (more technically if the mass quadrupole moment of a system changes over time) as during the merger of black holes, supernovae explosions and the like.