When I was growing up I’ve always heard about the “Big Bang Theory” which postulates that all matter and energy in the Universe was initially compressed into a single tiny mass which exploded outward about 13.8 billion years ago, with the explosion continually expanding to form the known Universe. I’ve also heard that theoretically the energy of the outward expansion will eventually dissipate, leading to the gravity of all existing matter pulling everything back together again with black holes also growing and consuming each other until all matter and energy is once again compressed into a single tiny mass, with the entire process then repeating itself over and over again.
However, this recent Forbes article that I saw initially sounds as if it supposedly overturns everything that everyone knows about the theory, saying “[The most common assumption of the Big Bang theory] isn’t just wrong, it’s nearly 40 years out of date! We are absolutely certain there was no singularity associated with the hot Big Bang, and there may not have even been a birth to space and time at all. Here’s what we know and how we know it.”— It sounds as if the article will totally destroy the Big Bang theory, but what does it actually say? https://www.forbes.com/sites/startswithabang/2018/07/27/there-was-no-big-bang-singularity/#3b6721f67d81
In recent years I’ve actually come across information a few times essentially saying “the Big Bang theory of the Universe is no longer thought to be valid,” in the same manner that the above article seems to say it, but I haven’t bothered to look into the claim. So when I came across this article I decided to examine it.
The article is actually rather long-winded, and it doesn’t offer easily interpreted “compare-and-contrast” summaries of the “traditional” Big Bang theory alongside the supposedly “new” claims that the article makes. But more surprisingly, after examining the article it became apparent that it only refutes a relatively minor aspect of the Big Bag theory which only some people still claim, it definitely doesn’t refute the entire Big Bang theory altogether as it rather deceptively initially seems to suggest. The article also doesn’t mention the potentially “cyclical” nature of “Big Bang expansions and contractions” as I’ve often heard, but I don’t necessarily fault it for that since that is a technically speculative theory (although in my opinion it is the most likely scenario.)
Following are points that that article makes:
— The article focuses on what it calls “the false idea of a singularity,” explaining that a “singularity” would theoretically be an instant where all time, matter, and energy in the Universe would be concentrated into a “single point.” The article states “We are absolutely certain there was no singularity associated with the hot Big Bang, and there may not have been a birth to space and time at all.” Most of the rest of the article elaborates on that theory.
— The article explains what is assumed to have happened in the Universe by extrapolating backwards in time, explaining that the farther back you go, the more matter would be clumped together and the more the Universe would be so incredibly hot that “individual protons and neutrons would be dissociated into quarks and gluons.” As you continue to go back into time, you would eventually theoretically (almost) reach a “singularity” where all time, matter, and energy would be contained within a single point.
— The article says that if the Universe was in fact actually at such a “singularity point” at the time of the the Big Bang, then “clear signatures” of that would be able to be observed today, such as “temperature fluctuations in the Big Bang’s leftover glow that would have tremendously large amplitudes.” However, the temperature fluctuations that exist today are only 1-part-in-30,000 smaller than what a “singularity” Big Bang would have created, apparently showing that the Big Bang did not occur starting from a “singularity point.” (Personally, I’ve always “correctly” been taught that the Big Bang initially started from a small dense blob of matter rather than just a single point. The article explains that scientists have understood that theory for about forty years despite many people still thinking otherwise.)
— The article then mentions a theory of a period of an “expansion” which apparently occurred before the Big Bang, which supposedly gave rise to the Big Bang and supplied the energy that went into the matter which is present today, saying the energy somehow arose out of the fabric of space itself. Apparently this “expansion” was not a particularly hot and dense state, and it was not a singularity. But based on what the article mentions about such a potential period of “expansion” I wasn’t really able to understand much about it. (And I wonder if a “contraction” from a previous Big Bang is what is actually supplying the energy and matter that scientists now attribute to such a “pre-Big Bang expansion.”)
— Only a genuine singularity would be a “true” start of time and space. It is theoretically possible that a singularity may have happened at some point before the Big Bang, however there is no scientific way of knowing when that happened, or even if it happened at all.