I know what you mean. It depends upon the perception one has. If you look outside, what you see and experience will one day vanish as nothing is eternal. Everything was made by an Unstruck primal sound vibration from the Timeless being. Everything is one and one is everything. When the stars, planets were made, the organisms emerged, they started to have duality that they are different from each other which is called duality. Humanity and all other species suffer pain due to this duality. The whole whole purpose of Gurbani is to tell the lost being that you are lost. Go back to the door where you came from. We came from the primal sound and the goal for all the souls is to go back now or in the future. This is how it is, the play and one time end. Gurbani tells us that whatever is found outside is also inside and inside He will be found. There are millions of Galaxies and planets: which was given in Gurbani before the current Science knew of it which is why NASA is exploring sri Guru Granth Sahib in USA and found many things which are proven facts. They even given the title: 'Lord of world' to Sri Guru Granth Sahib in their library. The planet we live in is Karm bhumi and there many like this one.
Eternal happiness cannot be defined by materialsm but by self realisation - who we really are where did we came from and why. That can be experienced from within not outside
There is a story about an atheist who met Sant Teja Singh ji (who was once an atheist himself).
A young man came and asked Sant ji: Sant ji you say there is God.
Sant ji: yes.
The man :show me where he is.
Sant ji :He is everywhere.
Man: No, I want to see him and if you claim he is, show me.
Sant ji kept quite for some time. After a while sant ji opened his eyes and said I am going to do Jaap Sahib.
you just look at me. As sant ji started Jaap Sahib, his face turned red and shiny. There was so much light that the man started hide his face from it.
After the paath was over Sant ji said, you are fortunate that Guru ji allowed me to show you the 'God's light'. You cannot expect to test the existence of 'God' each time an atheist questions.
Science can do the hard things by applying the algorithms and give you appliances and anyone can enjoy the fruits. To find the truth you will have to explore Gurbani yourself.