KNOWPIA
WELCOME TO KNOWPIA

**Quantum cosmology**^{[1]}^{[2]} is the attempt in theoretical physics to develop a quantum theory of the universe. This approach attempts to answer open questions of classical physical cosmology, particularly those related to the first phases of the universe.

Classical cosmology is based on Albert Einstein's general theory of relativity (GTR or simply GR) which describes the evolution of the universe very well, as long as you do not approach the Big Bang. It is the gravitational singularity and the Planck time where relativity theory fails to provide what must be demanded of a final theory of space and time. Therefore, a theory is needed that integrates relativity theory and quantum theory.^{[3]} Such an approach is attempted for instance with loop quantum cosmology, loop quantum gravity, string theory and causal set theory.^{[4]}

In quantum cosmology, the universe is treated as a wave function instead of classical spacetime.^{[5]}

- Bojowald, Martin (2011).
*Quantum Cosmology. A Fundamental Description of the Universe*. Lecture Notes in Physics. Vol. 835. Springer. ISBN 978-1-4419-8276-6.

**^**Bojowald, Martin (2015). "Quantum cosmology: A review".*Reports on Progress in Physics*.**78**(2): 023901. arXiv:1501.04899. Bibcode:2015RPPh...78b3901B. doi:10.1088/0034-4885/78/2/023901. PMID 25582917. S2CID 18463042.**^**Chiou, Dah-Wei (2015). "Loop quantum gravity".*International Journal of Modern Physics D*.**24**(1): 1530005–1530331. arXiv:1412.4362. Bibcode:2015IJMPD..2430005C. doi:10.1142/S0218271815300050. S2CID 16655619.**^**Stephen Hawking wrote 1999:*So what the singularity theorems are really telling us, is that the universe had a quantum origin, and that we need a theory of quantum cosmology, if we are to predict the present state of the universe.*"Quantum Cosmology, M-theory and the Anthropic Principle - Stephen Hawking". Archived from the original on 2015-02-14. Retrieved 2015-02-14.**^**Klebanov, Igor & Maldacena, Juan (2009). "Solving Quantum Field Theories via Curved Spacetimes".*Physics Today*.**62**(1): 28. Bibcode:2009PhT....62a..28K. doi:10.1063/1.3074260.**^**He, Dongshan; Gao, Dongfeng; Cai, Qing-yu (2014). "Spontaneous creation of the universe from nothing".*Physical Review D*.**89**(8): 083510. arXiv:1404.1207. Bibcode:2014PhRvD..89h3510H. doi:10.1103/PhysRevD.89.083510. S2CID 118371273.

- A Layman's Explanation of Quantum Cosmology
- Lectures on Quantum Cosmology by J.J. Halliwell