So let me set up a premise I'm under the impression we believe the universe is expanding and the farther away an object is the faster its retracting from us, we know this because of the light from distant objects stretches with space so we get red shift.. but light is subject to a doppler effect, as well as gravity in addition to the suspected expansion so how could we expect with any certainty to know how distant stars truly are if we dont know exactly the ratio of much redshirt is due to gravity, universal expansion, and the doppler effect. If were off even a little on the cause and original intensity(by little I mean lightyears) doesnt that make it exponentially more likely to be inaccurate?