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Cerenkov
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- TL;DR Summary
- Stephen Hawking and Jim Hartle pioneered the Euclidean approach to early universe cosmology. This involves the use of a technique called Imaginary Time. According to Hawking this technique was used at the 1982 Nuffield workshop.
http://inspirehep.net/search?p=773__w%3AC82/06/21.2+or+773__w%3AC82-06-21.2+and+980__a%3AConferencePaper
I am interested in the CMBR-related predictions that resulted from that workshop.
Hello.
I have three questions about a claim made by Stephen Hawking in his book, 'My Brief History' and I would be grateful to receive some help concerning it please. Here is a .pdf version of it.
http://vciastronomy.weebly.com/uplo...dge.commy_brief_history_-_stephen_hawking.pdfHere is the relevant section, from chapter 12, Imaginary Time.
I HAD been working mainly on black holes, but my interest in cosmology was renewed by the suggestion that the early universe had gone through a period of inflationary expansion. Its size would have grown at an ever-increasing rate, just as prices go up in the shops. In 1982, using Euclidean methods, I showed that such a universe would become slightly non-uniform. Similar results were obtained by the Russian scientist Viatcheslav Mukhanov about the same time, but that only became known later in the West.
These non-uniformities can be regarded as arising from thermal fluctuations due to the effective temperature in an inflationary universe that Gary Gibbons and I had discovered eight years earlier. Several other people later made similar predictions. I held a workshop in Cambridge, attended by all the major players in the field, and at this meeting we established most of our present picture of inflation, including the all-important density fluctuations that give rise to galaxy formation, and so to our existence.
This was ten years before the Cosmic Background Explorer (COBE) satellite recorded differences in the microwave background in different directions produced by the density fluctuations. So again, in the study of gravity, theory was ahead of experiment. These fluctuations were later confirmed by the Wilkinson Microwave Anisotropy Probe (WMAP) and the Planck satellite, and were found to agree exactly with predictions.
Now to my questions.
1.
Firstly, I read Hawking's words to mean that the fluctuations observed by WMAP and Planck were first predicted by him and Hartle, by their usage of the Euclidean approach and the Imaginary Time technique. Have I drawn a false conclusion, here?
2.
If that is so, then which fluctuations are these? These? https://physics.stackexchange.com/questions/155508/angular-power-spectrum-of-cmb Or some other?
3.
Or, if I have misread what Hawking is saying, could I please be informed as to what he actually means about the relationship between the Euclidean approach and the CMBR?
Any help given at my basic level would be much appreciated. Thank you.
Cerenkov.
I have three questions about a claim made by Stephen Hawking in his book, 'My Brief History' and I would be grateful to receive some help concerning it please. Here is a .pdf version of it.
http://vciastronomy.weebly.com/uplo...dge.commy_brief_history_-_stephen_hawking.pdfHere is the relevant section, from chapter 12, Imaginary Time.
I HAD been working mainly on black holes, but my interest in cosmology was renewed by the suggestion that the early universe had gone through a period of inflationary expansion. Its size would have grown at an ever-increasing rate, just as prices go up in the shops. In 1982, using Euclidean methods, I showed that such a universe would become slightly non-uniform. Similar results were obtained by the Russian scientist Viatcheslav Mukhanov about the same time, but that only became known later in the West.
These non-uniformities can be regarded as arising from thermal fluctuations due to the effective temperature in an inflationary universe that Gary Gibbons and I had discovered eight years earlier. Several other people later made similar predictions. I held a workshop in Cambridge, attended by all the major players in the field, and at this meeting we established most of our present picture of inflation, including the all-important density fluctuations that give rise to galaxy formation, and so to our existence.
This was ten years before the Cosmic Background Explorer (COBE) satellite recorded differences in the microwave background in different directions produced by the density fluctuations. So again, in the study of gravity, theory was ahead of experiment. These fluctuations were later confirmed by the Wilkinson Microwave Anisotropy Probe (WMAP) and the Planck satellite, and were found to agree exactly with predictions.
Now to my questions.
1.
Firstly, I read Hawking's words to mean that the fluctuations observed by WMAP and Planck were first predicted by him and Hartle, by their usage of the Euclidean approach and the Imaginary Time technique. Have I drawn a false conclusion, here?
2.
If that is so, then which fluctuations are these? These? https://physics.stackexchange.com/questions/155508/angular-power-spectrum-of-cmb Or some other?
3.
Or, if I have misread what Hawking is saying, could I please be informed as to what he actually means about the relationship between the Euclidean approach and the CMBR?
Any help given at my basic level would be much appreciated. Thank you.
Cerenkov.