How can we make sense of the Universe from the Buddhist perspective?

Looking at the stars, you can make sense of it as "seeing... seeing.. seeing...". Because that's the only thing you can be sure of. The entities you assume to exist based on seeing will always be fabrications that you can never sense.

When you think about the billions of galaxies or infinite space etc., you can make sense of it as "thinking... thinking... thinking...". Because that's the only thing you can be sure of. The entities you assume to exist based on thinking will always be fabrications that you can never sense.

Just ignore it. I dont remember exactly which súthra it is. Our nobel teacher once said dont try to search such things 1. End of the universe. 2. How the karma happens. 3. Life of lord buddha Because knowledge these will not helping you to follow nobel eight path.

Out in the outer space, there are billions of such galaxies and as far as we know its lifeless, or devoid of intelligent life, like us.

Well, "as far as we know" is the key point here. It's exactly the fact that the universe is so vast, that it's practically a mathematical impossibility to say we're the only intelligent life form ever existed. Dr. Neil deGrasse Tyson put it best:

Claiming there is no other life in the universe is like scooping up some water, looking at the cup and claiming there are no whales in the ocean.”

Or Dr. Carl Sagan's "Flatlanders" analogy is another good one about the limitation of humans knowledge. Keeping those possibilities in mind, the questions about the "miracle" or "paradox of complexity" automatically get resolved by themselves.

I know this is the kind of the question Buddha discouraged to ponder upon with the example of the poisonous arrow.

Exactly. It is a waste of time. We are suffering from illness and world needs to shift attention to the cure as described by Buddha.

But after 25 centuries, after what Newton and Einstien and Astronomers and Scientists have bought in light for us, the enormous size of our Universe. It is billions and billions of kilometers across, our earth is a small planet circling an average star which circles an ordinary galaxy on its periphery. Out in the outer space, there are billions of such galaxies and as far as we know its lifeless, or devoid of intelligent life, like us. And then there is empty space, huge empty space. The nothingness or emptiness of the universe.

In past I had spent some time ,when I was ignorant, thinking about such realities. All such realities are empty. They do not last forever. They are impermanent. They are changeable and perishable and therefore cause of suffering. Earth will get destroyed. Sun , Moon, Stars , Black holes , atoms all will one day get destroyed. Even the nothingness will not be there. As long as you cling to such realities you will keep coming back to existence. Even the laws of Physics are not permanent. There is no beauty in the constitution of Universe. In fact it might be ugly.

And then there is us. A miracle, what sets this question is the paradox of our complexity (biological) against the background of the emptiness of outer space. And here we have reached the conclusion of the first noble truth of Dukkha!!!

If Universe and us is a miracle then it is a ugly miracle. Existence , birth itself is suffering. That conclusion is actually a miracle. We have evolved from simple life to complex life. Complexity of a AI might leave you wondering how they created AI but it was a step by step process. Complexity of music might leave you wondering how they created the music but it was a step by step process. Body is also complex. But do you believe that you exist in the body ? No you don't. Body is without any self. Body is the cause of suffering as it will change and perish. Your craving for the beauty of the body might result in another rebirth. Abandon such cravings.

Looking at the star-filled night sky, as a Buddhist, how do I make sense of all this?

I think as a Buddhist , one would be dispassionate about such empty Dhammas.

There was no such thing as modern day language, the scientific method, Newtonian physics, or higher mathematics during The Buddha's time-period those things seem to have come into existence around the 17th Century.

So there was no possibility of anyone asking The Buddha or any arahant to prove or explain things in modern scientific terms. It's also not exactly clear what certain things in modern terms mean because modern language is different.

However the Pali canons mention all types of concepts that only relatively recently came in:

• Big Bang and Big Crunch (expansion and contraction of the universe)
• Time dilation (time moving at a different pace on other worlds)
• Cyclic model
• World systems like galaxies

During The Buddha's time he encouraged those with doubt to ask questions.

In modern times if an arahant well-developed in the six higher knowledges or paccekabuddha or sammasambuddha appears they should be able to easily scientifically prove their ideas through modern means if someone challenged them to.

Something like that actually happened when the arahant Kumara encountered an ancient atheist Prince Payasi, here's an exerpt:

"Well, Reverend Kumara, I had friends who followed the right path, who were very good people and citizens in every respect. By any right, as certain Holy men have said, they should have gone to the Heaven of the Thirty Three Devas. Yet, when one of them died, I said to him, "You have always been trustworthy and dependable. Certain Holy men say that, because of your lifestyle and because you followed the right path, you will be reborn in the Heaven of the Thirty Three Devas. If this is so, please come and tell me if it is true, or send a messenger to tell me if it is true. To date, they have neither contacted me nor sent a messenger."

"Hmm. Well, Prince… Consider this. In the Heaven of the Thirty Three Devas, time passes at a different pace, and people live much longer. In the period of our century, one hundred years, only a single day, twenty four hours would have passed for them. Thirty of these hundred year days make up one of their months, twelve such months make a year and a thousand such years is roughly the life span of those born into the Heaven of the Thirty Three Devas. Suppose your friend decided, "I will go back to that unclean world just long enough to deliver my message to the Prince – I shall set out tomorrow. Or perhaps, after I have seen some more of this place, in two or three days, I will set out to go see him." – would he have been able to?"

"Of course not, Reverend Kumara, because, by the reasoning you have given, we should all be long dead by the time he had spent three days there. However, I do not think that those born in the Heaven of the Thirty Three Devas would be so long lived, or that time could pass at a different pace. How do you know about their lifespan or their time?" (DN 23, Payasi Sutta)

The idea of time moving at a different pace on other worlds is something that only recently came in.

But remember there was no such thing as the scientific method or higher mathematics back then so one could challenge an arahant to experimentally prove something like we can now in modern times.

It seems like The Buddha is the only teacher in history who debated in a bold calm fearless manner claiming to know that his ways are true. Still in modern times I don't know if there's any teacher like that.

If someone really is an arahant and also well-developed in the six higher knowledges scientifically proving something should be an easy task for them.

This means in modern times if a skilled arahant or paccekabuddha arises and someone challenges them they should be able to scientifically prove that they are right...it would probably bedazzle and astonish the world...

I wonder however if there really are any arahants that exist in this world...

In the Kosala Sutta: The Kosalan the Buddha acknowledges such questions:

As far as the sun & moon revolve, illumining the directions with their light, there extends the thousand-fold cosmos. In that thousand-fold cosmos there are a thousand moons, a thousand suns,... And in that thousand-fold cosmos, the Great Brahma is reckoned supreme. Yet even in the Great Brahma there is still aberration, there is change. Seeing this, the instructed disciple of the noble ones grows disenchanted with that, he becomes dispassionate toward what is supreme, and even more so toward what is inferior....

For the disenchantment, this remedy:

There are these There are these eight dimensions of [mental] mastery. Which eight? (see sutta)

There may be other intelligent lifeforms out there, as there are billions of galaxies, each with billions of stars surrounded by planets. As physicist, futurist and science communicator Michio Kaku says, ants are not aware of human beings standing near them and looking at them. Similarly, there may be beings far more intelligent than us looking at us right now, but we may not be aware of them.

How does a Buddhist make sense of the billions of galaxies and stars and planets out there?

As we know, none of the planets, stars, galaxies will last forever. Everything dies out eventually, including our whole universe. Apparently, we could be living in a multiverse where there are many universes. An entire universe itself could experience birth and death, what more things inside them. Who knows? There could even be a multiverse of multiverses. But one thing for sure - everything changes and nothing lasts forever.

That's how a Buddhist should make sense of our glorious universe - everything changes and nothing lasts forever. "Sabbe sankhara anicca" - everything that is conditioned and compounded is impermanent.

The Buddhist should also remember one of the Buddha's last words from the Mahaparinibbana Sutta:

vayadhammā saṅkhārā, appamādena sampādetha.
All conditioned things are subject to decay, strive on with heedfulness!