The Buddha, being who he was, it was inevitable that people would often approach him to ask him questions about existential and philosophical questions about the universe. One famous incident of this was with the monk Malunkyaputta who threatened the Buddha that he would leave the Sangha if the Buddha not reveal to him the answers to his such questions. the Buddha refused and in doing so the Buddha reminded his disciples about the dangers of pursuing such idle questions, as the answering of such questions does not lead to enlightenment and the end of suffering.
Some might suggest that the Buddha declined to answer such questions because he did not have the answers. That may be the case, but we must remember that the Buddha did reveal many things about the universe that was unable to be known at the time, as such his knowledge base is surely greater than that of a normal human of the time. If we assume that he was more than human, and that he did in fact know the answers to such existential questions, then why did he not just teach all people back then? The answer to that question may be simpler than we think.
In many sutras, the Buddha states that he knew the individual workings of each person's mind and would teach everyone according to what will help them most towards enlightenment. These were called expedient means. As such, what he taught newer converts were different were different from what he taught his most experienced disciples. And even though everything the Buddha taught shared the common ultimate goal of enlightenment and the end of suffering, the means, methods and intermediate goals could look very different for each person.
What this all means is that what are idle questions for us, are not idle questions for others. For example, the question of what to do about climate change is very important to people? But is the question of what to do about climate change important to ants? For the ants, who have no control over the climate of the planet, as humans do, to wonder and worry about such questions would be meaningless and quite possibly lead it to be eaten caught in a spider web. Similarly, to worry about the size of the universe today is dangerous for us in this lifetime if it hinders our goal of enlightenment. (*Buddha understood and accepted man's curious nature, he was only objecting to curiosity when it stops people from spiritual pursuits.)
So does this mean we should or should not wonder about when did life start or how big is the universe? The answers is we can, but we should not let the pursuit of such questions remove us from finding the truth about life and suffering. In fact, Buddha listed the kinds of beings that cannot attain enlightenment:
1) Born as an Animal - lack the capacity for wisdom
2) Born as a Ghost - Too much yearning
3) Born in Hell - Too much suffering
4) Born in one of the Heavens - Too much Happiness
5) Born as human but disabled in some manner- Physically or mentally incapable
6) Born as human but skeptical - Includes scientists or those that require proof before reason
While the Buddha does welcome people to challenge his teachings and not accept them at face value, there will be certainly be those that do never accept his teachings because of skepticism. And many would use his unwillingness to answer certain questions or to provide fantastical seemingly impossible stories as evidence for their skepticism. Obviously, I do not wish the readers of this site to fall prey to such skepticism. It is very easy to conclude what we see in this life as what is real and what we don't see as unreal, but what is easy is not always what is true.
What all of this means is, it is important to treat Buddhism like learning any other skill, you must start at the beginning before moving up. Start with the Four Noble Truths and the Noble Eightfold Path. Once you understand and accept those then you can build upon that foundation. That is how the Buddha taught his disciples. If you are willing to put forth the effort to study and practice earnestly, you will see that some questions which you find unanswered in the text at the beginning of your study, can be solved by yourself later on without being told by anyone.
Some might suggest that the Buddha declined to answer such questions because he did not have the answers. That may be the case, but we must remember that the Buddha did reveal many things about the universe that was unable to be known at the time, as such his knowledge base is surely greater than that of a normal human of the time. If we assume that he was more than human, and that he did in fact know the answers to such existential questions, then why did he not just teach all people back then? The answer to that question may be simpler than we think.
In many sutras, the Buddha states that he knew the individual workings of each person's mind and would teach everyone according to what will help them most towards enlightenment. These were called expedient means. As such, what he taught newer converts were different were different from what he taught his most experienced disciples. And even though everything the Buddha taught shared the common ultimate goal of enlightenment and the end of suffering, the means, methods and intermediate goals could look very different for each person.
What this all means is that what are idle questions for us, are not idle questions for others. For example, the question of what to do about climate change is very important to people? But is the question of what to do about climate change important to ants? For the ants, who have no control over the climate of the planet, as humans do, to wonder and worry about such questions would be meaningless and quite possibly lead it to be eaten caught in a spider web. Similarly, to worry about the size of the universe today is dangerous for us in this lifetime if it hinders our goal of enlightenment. (*Buddha understood and accepted man's curious nature, he was only objecting to curiosity when it stops people from spiritual pursuits.)
So does this mean we should or should not wonder about when did life start or how big is the universe? The answers is we can, but we should not let the pursuit of such questions remove us from finding the truth about life and suffering. In fact, Buddha listed the kinds of beings that cannot attain enlightenment:
1) Born as an Animal - lack the capacity for wisdom
2) Born as a Ghost - Too much yearning
3) Born in Hell - Too much suffering
4) Born in one of the Heavens - Too much Happiness
5) Born as human but disabled in some manner- Physically or mentally incapable
6) Born as human but skeptical - Includes scientists or those that require proof before reason
While the Buddha does welcome people to challenge his teachings and not accept them at face value, there will be certainly be those that do never accept his teachings because of skepticism. And many would use his unwillingness to answer certain questions or to provide fantastical seemingly impossible stories as evidence for their skepticism. Obviously, I do not wish the readers of this site to fall prey to such skepticism. It is very easy to conclude what we see in this life as what is real and what we don't see as unreal, but what is easy is not always what is true.
What all of this means is, it is important to treat Buddhism like learning any other skill, you must start at the beginning before moving up. Start with the Four Noble Truths and the Noble Eightfold Path. Once you understand and accept those then you can build upon that foundation. That is how the Buddha taught his disciples. If you are willing to put forth the effort to study and practice earnestly, you will see that some questions which you find unanswered in the text at the beginning of your study, can be solved by yourself later on without being told by anyone.