Big Crunch or Big Rip?

[dipayankar]

Hi Antonio, what would be the height under consideration?

General relativity asserts spacetime curvature is directly proportional to the mass-energy content of a particular location which makes the universal constant as absolute constant acceleration. In Earth's vicinity it is the acceleration constant of gravity. This constant varies inversely with height.

[AntonioLao]

the height under consideration

The 'h' in the mechanical potential energy mgh where g is the constant of gravitational acceleration.

[dipayankar]

In the context of your earlier post, I havent come across any equation that defines the potential energy of earth since there is not reference height.

The 'h' in the mechanical potential energy mgh where g is the constant of gravitational acceleration.

[AntonioLao]

I havent come across any equation that defines the potential energy

This can be found easily in Physics 101 in most college courses. But still for completeness, the potential energy must be added to the kinetic energy for constant total energy of a conservative mechanical system. Most projectile kinematics obey this formulation and most rocket scientists would also agree.

[Max™]

It would be the distance from the Earths surface, which is merely a location that has a well documented gravitational potential.

It changes as you move up, or down (at the center of the Earth, you would feel much less, possibly zero gravity, due to the mass of the rest of the Earth pulling at you equally in all directions).

The equations you are looking for are the Einstein Field Equations, and the values in question would be the amount of mass in the Earth, it's size, and it's apparent velocity.

[Profpat]

Will the Universe end in a Big crunch or a Big RIP? Or is there other means that the Universe will end in??

Hi Dipayankar;

A little research yielded this from Wiki:

Ultimate fate of the universe
Main article: Ultimate fate of the universe
As with interpretations of what happened in the very early universe, advances in fundamental physics are required before it will be possible to know the ultimate fate of the universe with any certainty. Below are some of the main possibilities.

[edit] Big freeze: 1014 years and beyond

Main articles: Future of an expanding universe and Heat death of the universe
This scenario is generally considered to be the most likely, as it occurs if the universe continues expanding as it has been. Over a time scale on the order of 1014 years or less, existing stars burn out, stars cease to be created, and the universe goes dark.[11], §IID. Over a much longer time scale in the eras following this, the galaxy evaporates as the stellar remnants comprising it escape into space, and black holes evaporate via Hawking radiation.[11], §III, §IVG. In some grand unified theories, proton decay will convert the remaining interstellar gas and stellar remnants into leptons (such as positrons and electrons) and photons. Some positrons and electrons will then recombine into photons.[11], §IV, §VF. In this case, the universe has reached a high-entropy state consisting of a bath of particles and low-energy radiation. It is not known however whether it eventually achieves thermodynamic equilibrium.[11], §VIB, VID.

[edit] Big crunch: 100+ billion years

See also: Big Crunch
If the energy density of dark energy were negative or the universe were closed, then it would be possible that the expansion of the universe would reverse and the universe would contract towards a hot, dense state. This is often proposed as part of an oscillatory universe scenario, such as the cyclic model. Current observations suggest that this model of the universe is unlikely to be correct, and the expansion will continue or even accelerate.

[edit] Big rip: 200+ billion years

See also: Big Rip
This scenario is possible only if the energy density of dark energy actually increases without limit over time. Such dark energy is called phantom energy and is unlike any known kind of energy. In this case, the expansion rate of the universe will increase without limit. Gravitationally bound systems, such as clusters of galaxies, galaxies, and ultimately the solar system will be torn apart. Eventually the expansion will be so rapid as to overcome the electromagnetic forces holding molecules and atoms together. Finally even atomic nuclei will be torn apart and the universe as we know it will end in an unusual kind of gravitational singularity. In other words, the universe will expand so much that the electromagnetic force holding things together will fall to this expansion, making things fall apart.

[edit] Vacuum metastability event

See also: False vacuum
If our universe is in a very long-lived false vacuum, it is possible that the universe will tunnel into a lower energy state. If this happens, all structures will be destroyed instantaneously, without any forewarning.

Name your poison,

Best,

Pat

[dipayankar]

Only 1014 years or less for Big Freeze? I thought our sun itself would burn for another 5 billion years...

Hi Dipayankar;

A little research yielded this from Wiki:

Ultimate fate of the universe
Main article: Ultimate fate of the universe
As with interpretations of what happened in the very early universe, advances in fundamental physics are required before it will be possible to know the ultimate fate of the universe with any certainty. Below are some of the main possibilities.

[edit] Big freeze: 1014 years and beyond

Main articles: Future of an expanding universe and Heat death of the universe
This scenario is generally considered to be the most likely, as it occurs if the universe continues expanding as it has been. Over a time scale on the order of 1014 years or less, existing stars burn out, stars cease to be created, and the universe goes dark.[11], §IID. Over a much longer time scale in the eras following this, the galaxy evaporates as the stellar remnants comprising it escape into space, and black holes evaporate via Hawking radiation.[11], §III, §IVG. In some grand unified theories, proton decay will convert the remaining interstellar gas and stellar remnants into leptons (such as positrons and electrons) and photons. Some positrons and electrons will then recombine into photons.[11], §IV, §VF. In this case, the universe has reached a high-entropy state consisting of a bath of particles and low-energy radiation. It is not known however whether it eventually achieves thermodynamic equilibrium.[11], §VIB, VID.

[edit] Big crunch: 100+ billion years

See also: Big Crunch
If the energy density of dark energy were negative or the universe were closed, then it would be possible that the expansion of the universe would reverse and the universe would contract towards a hot, dense state. This is often proposed as part of an oscillatory universe scenario, such as the cyclic model. Current observations suggest that this model of the universe is unlikely to be correct, and the expansion will continue or even accelerate.

[edit] Big rip: 200+ billion years

See also: Big Rip
This scenario is possible only if the energy density of dark energy actually increases without limit over time. Such dark energy is called phantom energy and is unlike any known kind of energy. In this case, the expansion rate of the universe will increase without limit. Gravitationally bound systems, such as clusters of galaxies, galaxies, and ultimately the solar system will be torn apart. Eventually the expansion will be so rapid as to overcome the electromagnetic forces holding molecules and atoms together. Finally even atomic nuclei will be torn apart and the universe as we know it will end in an unusual kind of gravitational singularity. In other words, the universe will expand so much that the electromagnetic force holding things together will fall to this expansion, making things fall apart.

[edit] Vacuum metastability event

See also: False vacuum
If our universe is in a very long-lived false vacuum, it is possible that the universe will tunnel into a lower energy state. If this happens, all structures will be destroyed instantaneously, without any forewarning.

Name your poison,

Best,

Pat

[dipayankar]

I gues I know that . What I am asking is what would be the potential energy of earth since there is no height reference...

This can be found easily in Physics 101 in most college courses. But still for completeness, the potential energy must be added to the kinetic energy for constant total energy of a conservative mechanical system. Most projectile kinematics obey this formulation and most rocket scientists would also agree.

[Max™]

10 to power 140 I think the number was.

Not 1,014.

Proton Decay will take at least 10 to power 64 years, evidenced by you withstanding your own mass.

[Profpat]

Only 1014 years or less for Big Freeze? I thought our sun itself would burn for another 5 billion years...

How about this as a timeline for the big freeze:


That is 10 to the 1500th power for matter to decay to iron

[edit] Matter decays into iron

101500 years from now In 101500 years, cold fusion occurring via quantum tunnelling should make the light nuclei in ordinary matter fuse into iron-56 nuclei (see isotopes of iron.) Fission and alpha-particle emission should make heavy nuclei also decay to iron, leaving stellar-mass objects as cold spheres of iron.[8]

[edit] Collapse of iron star to black hole

to years from now Quantum tunnelling should also turn large objects into black holes. Depending on the assumptions made, the time this takes to happen can be calculated as from years to years. (To calculate the value of such numbers, see tetration.) Quantum tunnelling may also make iron stars collapse into neutron stars in around years.[8]


I guess we'll be left with what we started with Dip, protons neutrons and photons.

Best,

Pat