Much has been written (including by myself, several times) regarding the tension between the biblical story of creation and how science understands the formation of our world. This tension is based on taking the biblical story literally, and accepting the current scientific understanding as being accurate, despite there being constant changes — and disagreements — regarding what scientists hypothesize. One of the challenges regarding reconciling the two is the dearth of universally accepted traditional sources dealing with these issues.
This lack of sources is based primarily on two factors. First of all, the sources that the traditional community rely on for guidance (e.g. the Rishonim) lived well before this particular tension existed (as the scientists of their times had reached different conclusions than those reached by scientists in our generation); these traditional commentators could not try to resolve an issue that did not yet exist. True, there were other points of tension between the Torah and science that they had to deal with, and we can learn much from how they dealt with them, but without any explicit direction about a specific tension, the traditional community has, to a large extent, been handicapped in its ability to confidently address issues that arose after those sources could deal with them.
Secondly, the Talmud (Chagigah 11b) tells us that issues surrounding the creation story should not be taught publicly (or even privately to more than one student at a time), thereby preventing the dissemination (in person or in print) of the thoughts of traditionally-minded intellectual giants on the topic. Because of this ban, only obscure references to anything beyond what is written in the Torah (and is not included in, or consistent with, its literal creation narrative) appear in the traditional literature.
Although it is unclear precisely what does (and does not) fall under the category of “the creation story” and therefore cannot be shared, we can surmise that the age of the universe (if we assume it’s older than 6,000 years) qualifies, and with good reason. Until the “big bang theory” was widely accepted by the scientific community (which was not until the 20th Century), the tension between the biblical creation story and science was whether the world had a beginning (“olam chadash,” a “new” world), as the bible stated, or had always existed (“olam kadmone,” an “old” world), as scientists maintained. In this context, teaching publicly that the world was millions (or billions) of years old would make it much more difficult for many to still believe in a “new” world (i.e. one with a beginning), with a Creator. Even if there were individuals who understood that it didn’t matter how many years it had been since creation, since as long as it was a “creation” there must be a “Creator,” it was more advisable to keep the age of the universe under wraps so as not to confuse the many who would not (or might not) maintain a connection to the Creator if they knew how old the world really was.
Whether this still qualifies as “the creation story” and therefore should not be taught publicly, or if the end of the “olam chadash/olam kadmone” debate means it no longer qualifies, doesn’t mean there aren’t other aspects that still qualify. [I am of the belief that even though there are valid, and strong, answers to the global flood issues, teaching them to others qualifies as “Ma’aseh B’reishis.”] The bottom line, though, is that resistance to the possibility of a world created more than 6,000 years ago still exists in the traditional community, as does resistance to the notion that the Creator may have used evolution as part of His creation process, since many associate these concepts with atheism. [How the Creator formed the world to get it to the state He wanted it, and the length of time He took to do so, has no bearing on His existence.] And because there is nothing overt in the traditional literature that teaches otherwise, this resistance will likely continue for a very long time (perhaps with good reason). Nevertheless, there may be a very traditional source (the Talmud itself) that opens the door to other possibilities.
When the Talmud (K’subos 8a) discusses the blessings made when a new marriage is celebrated (what we call “Sheva B’rachos,” although one of the seven blessings is the one made over wine), it relates how at the wedding Rebbe made for his son they only said five blessings (besides the one over the wine), while at the wedding Rav Ashi made for his son they made six (plus one over the wine). The blessing that Rebbe didn’t make that Rav Ashi did (as do we) was “Yotzer Ha’adam” (see Rashi), the second blessing (aside from the one over the wine), and the first (and shorter) of the two that end with “Yotzer Ha’adam.” After suggesting, and rejecting, that this difference of opinion was based on whether there were two separate acts of creation for mankind (one for the male and one for the female), and therefore two separate blessings over the creation of man are made, or there was just one act of creation (male and female simultaneously), and therefore only one blessing, the Talmud concludes that both agree that mankind was created with one act of creation. Instead, the Talmud concludes, the difference of opinion is whether the blessings should reflect how mankind was actually created (male and female simultaneously, and therefore only one blessing), or how G-d had originally intended to create mankind (separately, using two acts of creation, and therefore two separate blessings), even if, for practical reasons, it was necessary to actually create man in one act of creation.
From the verses quoted (B’reishis 1:27 and 5:2; we’ll put aside where 2:7 fits in, at least for now, although from the connection the commentators make with Eiruvin 18a it is obvious that they understood 2:7 to be describing man’s actual creation) it becomes apparent (see Maharsha) that the description of mankind as it appears in the sixth day of creation does not reflect how man was actually created, but how G-d would have created man had there not been other considerations. Allow me to repeat that for emphasis: the creation story as it appears at the very beginning of the Torah, or at least the part of the sixth day that describes the creation of man, is not (at least according to the Talmud) literally the way man was created. Does this mean that nothing described in the six days of creation (1:1-1:31) reflects how G-d actually created them? Of course not. For all we know, the only exception is how mankind was created; G-d may have created everything else exactly as He had originally intended. Even the other things created on the sixth day may have been created exactly as described there. But it does indicate that what is described in the first six days of creation reflects G-d’s original intent, which was not necessarily how He actually created them.
Once we have established that the Torah’s description of the six days of creation is not meant to reflect how G-d actually created the world (even if some of the descriptions could also match the actual creation), there is no need for it to match how scientists describe the formation of the universe (or any of its contents). If the scientists are wrong, their description is meaningless. But even if they are right, they would be describing how G-d actually created the world, not how G-d had originally intended to create it. [Similarly, any discrepancy between the description of the first six days of creation and any subsequent description of creation could also be attributed to the difference between how G-d originally intended to create things and how He actually created them.]