General Discussion
In reply to the discussion: The universe is much bigger than big [View all]cpwm17
(3,829 posts)but the scientific method has proven itself reliable for finding the best explanations for how things work. No other method compares including deliberate ignorance and faith.
Scientists know the size of our universe through several methods. The intrinsic brightness of several objects are known. By observing their apparent brightness from Earth, and comparing it with their intrinsic brightness, scientists can know how far they are.
Through this method scientists have discovered that an astronomical object's distance is proportional to its receding velocity away from Earth. This allows them to measure the distance of all objects by their receding velocity. These various methods paint a consistent picture concerning our Universe's size and speed of expansion.
The beginning of our Universe isn't the beginning of existence and time. There is great evidence for the Big Bang which scientists study in detail.
"and the dark matter is what is pushing everything apart... to the point where molecules, even atoms are going to separate. bullshit."
Yes it is bullshit, and scientists don't claim that. The internal forces in atoms, planets, stars, and galaxies are much too great to separate these objects by any very weak dark energy, which only comes into play on extremely huge scales. Scientists don't claim to know what the dark energy is, and some scientists are looking for alternate explanations for the accelerating expansion of our Universe. Only science can find the answers.