The Universe Before the Big Bang: Cosmology and String Theory

by Maurizio Gasperini

PTerms such as "expanding Universe", "big bang", and "initial singularity", are nowadays part of our common language. The idea that the Universe we observe today originated from an enormous explosion (big bang) is now well known and widely accepted, at all levels, in modern popular culture. But what happens to the Universe before the big bang? And would it make any sense at all to ask such a question? In fact, recent progress in theoretical physics, and in particular in String Theory, suggests answers to the above questions, providing us with mathematical tools able in principle to reconstruct the history of the Universe even for times before the big bang.pIn the emerging cosmological scenario the Universe, at the epoch of the big bang, instead of being a "new born baby" was actually a rather "aged" creature in the middle of its possibly infinitely enduring evolution. The aim of this book is to convey this picture in non-technical language accessibile also to non-specialists. The author, himself a leading cosmologist, draws attention to ongoing and future observations that might reveal relics of an era before the big bang.

Genres: Science, Nonfiction, Physics

219 pages, Hardcover

First published January 1, 2002

Reviews

[Aroosha Dehghan · Rating 4 out of 5]

جهان چطور پدید اومد؟
این یکی از اصلی‌ترین پرسش‌های بشر در طول تاریخ بوده و پاسخ‌های مختلفی هم داشته؛ جهان ازلی، خدا، تکامل و...
تا سال‌های اخیر بیگ‌بنگ یا انفجار بزرگ یکی از نظرات مهم برای آغاز جهان شمرده می‌شد ولی این نظریه خودش پرسش تازه‌ای رو پدید میاره. بیگ‌‌بنگ آغاز همه چیزه یا آغازی برای شکل کنونی جهان؟
پاسخ اینه که نمی‌دونیم!
در لحظه‌‌ی انفجار بزرگ ما یک تکینگی داریم؛ یعنی همه‌ی جهان در یک نقطه با چگالی بی‌نهایت جمع شدند و این تکینگی اون انفجار هستی‌ساز رو شکل داد. یکی از ویژگی‌های نقطه‌ی تکین اینه که در اون لحظه تمام قوانین فیزیک که تا این لحظه شناخته و کشف شدند بی‌معنا میشن پس ما نمی‌تونیم با دانش و تجهیزات فعلیمون فیزیک لحظه‌ی انفجار رو فرمول‌بندی کنیم. در نتیجه، نمیشه بفهمیم که قبل از این انفجار دقیقا چه خبر بوده. فقط می‌تونیم نظریاتی رو مطرح کنیم و اون‌ها رو بسنیجیم تا ببینیم منجر به چنین تکینگی‌ای میشن یا نه.
یکی از ابزارهای ما برای این کار نظریه‌ی ریسمانه که به ما این امکان رو میده تا با ابزار ریاضی کیهان رو بازسازی کنیم؛ حتی پیش از بیگ‌بنگ!
یکی از ویژگی‌های خیلی خوب این کتاب، اینه که برای مخاطب عام نوشته شده و اگرچه موضوعی که مطرح کرده بسیار تخصصیه اما هرکسی با یک دانش حداقلی از فیزیک می‌تونه متوجه مطلب بشه. از طرفی، اگرچه محاسبات و ریاضیات بیچاره‌کننده‌ی فیزیک تو این کتاب نیست اما مخاطب تخصصی هم می‌تونه ازش استفاده کنه تا دید بهتری درباره‌ی جهان پیش از انفجار به دست بیاره و شاید ایده‌هایی به ذهنش برسه که پاسخ مناسب‌تری برای پرسش ابتدایی ماست؛ «جهان چطور پدید اومد؟»

[Voyt · Rating 4 out of 5]

Avoiding singularity.
POSTED AT AMAZON 2009
New cosmological solutions (models for the Universe that were not contemplated by general relativity) are suggested by physicist Gabriele Veneziano in collaboration with the author. Therefore, just to simplify, we read the Big Bang took place, but it did not involved a moment of infinite density, and inflation took place before not after Big Bang. Such conclusion can be obtained by quantum loop approach. But here we have the hazarded guesses by using symmetries of quantum strings - time did not have a a beginning and will not have an end. Such scenario is called "symmetry of time reversal" where dilation field plays the role. Mentioned is as well "ekpyriotic" model based on strings (for details check excellent: "Endless Universe" by Steinhardt and Turok where they did much better job explaining riddles of standard inflationary model vs. string models).
Fascinating topics indeed. Unfortunately I tend to agree with the first reviewer (quote): "this is not a book written in non-technical language as the publisher claims". It is more than popular dissertation being closer to scientific presentation, where just a few plottings and illustrations are difficult to understand. I often struggled reading verbal descriptions of math equations (for example: "An expansion of the partition function in a series of higher-genus world sheets thus becomes an expansion in powers of the exponential of the dilation, exp Æ"). I would clearly prefer math formulas (when not too complicated) rather than "textural" approach. Author chose rather cumbersome way to explain differences between Einstein's and string geometry describing and picturing evolution of the spacial radius R and horizon radius c/H for a model of Universe (nothing to mention that concepts of both: spacial and horizon radius, are hard to grasp). Same relates to graphs picturing frequency and energy density of gravitational background radiation, where log scale is introduced, but text refers to straight numbers - confusing for inexperienced reader.
Lack of glossary of terms is hugely disappointing. Buy this book only if you are a die-hard cosmology follower. Otherwise I strongly recommend easier, greatly illustrated (in colors) and compact article from Scientific American magazine: "Was the big bang really the beginning of time?" by Gabriele Veneziano.
Anyway, lots depends on Planck space mission. It may or may not confirm/reject quantum string models, even wraparound models. Time will tell.