Objects do exist without us observing them

Q: Do objects exist without us observing them? 

Krishna: This is the same Q Einstein asked, it seems. 'Does the moon exist when nobody is looking?'

In May 1935, Albert Einstein, Boris Podolsky and Nathan Rosen published an argument that quantum mechanics fails to provide a complete description of physical reality. 

Elementary particles do not need to be in a particular place until they are observed and then that's where they are.

Okay, if it doesn't exist when we don't look at the moon, how did science say how it came into existence in the first place? How did all those craters appear with meteor impacts? If nothing was there what did these meteors struck? Empty space? How did the moon's mountains and valleys come into existence? 

Or do they appear suddenly as soon as we look at the moon? The same way to everyone?

Fundamental to any physical theory is the principle of determinism. That means a system evolves smoothly from one state to the next. This is the reason that physical theories can make predictions in the first place. Without determinism, we'd have no predictability in science at all. The one thing that quantum theory can do well is make predictions.

The big bang, evolution of our universe, the scientific principles it follows to run - the birth of Stars and planets like our Earth,  changes in its evolutionary process, life coming into existence and its evolution - are they not real without us observing them earlier? 

We have solid evidence to prove that Earth and other planets, Sun   existed even before we observed them or looked at them and felt them. 

According to experts (2), 

The Copenhagen interpretation of quantum theory separates deterministic evolution from measurement. That means that quantum states exist and evolve deterministically. However, measurements are different. They irreversibly change the quantum state. This means that the measured value cannot be said to exist before it was measured. This is the thing that people find difficult to comprehend. That's because most people have a notion of what is called local realism; i.e., that the properties of an object are fixed and local to the object. This property of local realism was used by none other than Einstein to show that quantum theory must be incomplete. Furthermore, Bell's theorem tells us quantum theory does not satisfy local realism. This was put to the test using entangled particles. Bell's inequality is derived by assuming local realism. All experiments conducted with entangled particles show that they violate Bell's inequality. This suggests that local realism cannot be sustained.

Thus, ultimately we must accept that the reality we attribute to measured properties of objects is something of an illusion. The world is a little stranger than people think. Although this strangeness only really manifests itself on the quantum scale (for the most part).

However, the big difference between classical determinism and quantum determinism, is that the properties of the object do not depend on being measured with the classical case.

Yes, people explain that the moon is there when you aren't looking because of decoherence, but that is merely entanglement of the moon with the environment, its interaction with the environment. The impact of meteors, formation of craters, rocks turning into dust, aren't all these things happening?  In principle this remains a superposition.

Pascual Jordan put it this way: “Observations not only disturb what has to be measured, they produce it….We compel [the electron] to assume a definite position…. We ourselves produce the results of measurements!

Einstein said (1): That which really exists in B should …not depend on what kind of measurement is carried out in part
of space A; it should also be independent of whether or not any measurement at all is carried out in
space A. If one adheres to this program, one can hardly consider the quantum-theoretical description
as a complete representation of the physically real. If one tries to do so in spite of this, one has to
assume that the physically real in B suffers a sudden change as a result of a measurement in A.
My instinct for physics bristles at this.

And added: "I cannot seriously believe in [the quantum theory] because it cannot be reconciled with the idea that physics should represent a reality in time and space, free from spooky actions at a distance.”

( The “spooky actions at a distance”  is the acquisition of a definite value of a property by the system in region B by virtue of the measurement carried out in region A.) 

If you try to understand Quantum Mechanics as a non physicist, your brain goes into a dizzy state. So 

let me stop now.

The final answer to your Q is "Yes, objects do exist without us observing them". And there is evidence that they do exist. 

Trees grow in the forest [ seeds germinate, grow, turn into trees - they have some age which you can tell by observing the growth rings.] By seeing a tall tree, you can say it existed from the time it was a seed,  to this stage.

Tree rings

Wild animals live in the forest. But when a Tiger roars in the wilderness, the surrounding air gets disturbed, causes movement in the particles  and produces sound waves but there must be ears to receive that sound and 'hear' it and 'feel' it. Without the ears to receive the waves and a brain to interpret it as the tiger's roar, the process is incomplete and there won't be any use! But can you say the Tiger didn't roar? Or that it didn't exist to roar? You can't! The Tiger did roar. And it did exist to grow like any life form from a  cub to the adult stage to roar that particular way. But when there are no receptors to receive the tiger's roar, the entire process has no significance at all!

This is a weird world.  Try to get grips with it!

Footnotes:

1. https://cp3.irmp.ucl.ac.be/~maltoni/PHY1222/mermin_moon.pdf

2. https://www.quora.com/Is-it-true-that-objects-dont-exist-until-we-o...