Attempts At Falsifying The Strong Energy Condition
While the intent of the energy conditions is to provide simple criteria which rule out many unphysical situations while admitting any physically reasonable situation, in fact, at least when one introduces an effective field modeling some quantum mechanical effects, some possible matter tensors which are known to be physically reasonable and even realistic because they have been experimentally verified to actually fail various energy conditions. In particular, in the Casimir effect, in the region between two conducting plates held parallel at a very small separation d, there is a negative energy density
between the plates. (Be mindful, though, that the Casimir effect is topological, in that the sign of the vacuum energy depends on both the geometry and topology of the configuration. Being negative for parallel plates, the vacuum energy is positive for a conducting sphere.) Fortunately, various quantum inequalities suggest that a suitable averaged energy condition may be satisfied in such cases. In particular, the averaged null energy condition is satisfied in the Casimir effect. Indeed, for energy-momentum tensors arising from effective field theories on Minkowski spacetime, the averaged null energy condition holds for everyday quantum fields. Extending these results is an open problem.
The strong energy condition is obeyed by all normal/Newtonian matter, but a false vacuum can violate it. Consider the linear barotropic equation state
- ,
where is the matter energy density, is the matter pressure, and is a constant. In the case where, which is known as the false vacuum, the strong energy condition is violated. However, this equation of state only becomes relevant above temperatures of at least Kelvin. This would only happen under highly extreme conditions when quantum effects become dominant, and where classical general relativity would not apply. The main reason for wanting to falsify the strong energy condition is to avoid the initial singularity in the universe. The aforementioned suggests that a non-singular universe model would not obey the laws of classical physics at all times in the past.
Read more about this topic: Energy Condition
Famous quotes containing the words attempts, falsifying, strong, energy and/or condition:
“Amid attempts to protect elephants from ivory poachers and dolphins from tuna nets, the rights of children go remarkably unremarked.”
—Anna Quindlen (b. 1952)
“I sit in the top of the wood, my eyes closed.
Inaction, no falsifying dream
Between my hooked head and hooked feet:
Or in sleep rehearse perfect kills and eat.”
—Ted Hughes (b. 1930)
“Our science has become terrible, our research dangerous, our findings deadly. We physicists have to make peace with reality. Reality is not as strong as we are. We will ruin reality.”
—Friedrich Dürrenmatt (1921–1990)
“A government deriving its energy from the will of the society, and operating, by the reason of its measures, on the understanding and interest of the society ... is the government for which philosophy has been searching and humanity been fighting from the most remote ages ... which it is the glory of America to have invented, and her unrivalled happiness to possess.”
—James Madison (1751–1836)
“Such condition of suspended judgment indeed, in its more genial development and under felicitous culture, is but the expectation, the receptivity, of the faithful scholar, determined not to foreclose what is still a question—the “philosophic temper,” in short, for which a survival of query will be still the salt of truth, even in the most absolutely ascertained knowledge.”
—Walter Pater (1839–1894)