Recent content by substitute materials

So the problem is synchronizing clocks to define the beginning of the travelers journey, yes? In Ibis' 2 planet example we can use the passing of the distant planet as the starting point, but we will disagree about when that happened, correct? If we extend the buoy from Nugatory's response to...

Instead of a twin paradox, let’s just consider an inbound starship approaching Earth at relativistic speed. The traveler is on a flyby mission, he will never change speed or direction. We will disagree with the traveler on how much time will have elapsed when he passes Earth. The discrepancy can...

The method that was explained to me measures the sound horizon of the Baryon Acoustic Oscillations in the CMB. Basically, the sound horizon shows us the scale on which inhomogeneities formed in the early universe, which should correspond to the spatial separation of galaxies in the modern...

Ok think I've got it. Thanks all!

What you both seem to be saying is that any form of energy that doesn't dilute as volume changes will exert negative pressure, yes? Shrinking a container with matter in it will do work on it, but not so with a container filled with dark energy. So this means that work is done on the universe by...

interesting, I didn't realize that this would be true. I realize you are trying to explain this without referring to pressure Kimbyd, but I'm getting stuck on it. I think I understand that the matter in our particular universe has a pressure dictated by H- a sort of momentum in no direction...

I think I get this, I understand the balancing act of rate of expansion and gravitation in a matter dominated world. As you have said elsewhere on the site Kimbyd, it is a good analogy to escape velocity. I can see how this would only be stable, remaining flat, if the mass/energy were perfectly...

I think I have a question which is very similar, so I won't start a new thread: Dark Energy does 2 things in lambdaCDM as I understand it. First it provides a repulsive force that is accelerating the expansion of the universe, and secondly it constitutes the missing energy to bring the density...

As far as I understand, the simple blue-to-red temperature knob is just controlling the flow of hot engine coolant into the passenger compartment heater core. That heater core and the AC evaporator are in the same airstream with the same blower, so when you turn on the AC and then turn the...

Another option I like is to use when it is just slightly too warm is the defrost setting, which cycles the AC on a timer to provide dehumidification, in my old subaru outback its on for ~10 seconds then off for 10 seconds. This probably wears out the clutch on the AC compressor though...

I have operated under the assumption that since there is no temperature sensor in my car either, it is simply mixing warm air to achieve the desired temperature, and thus not saving any fuel to move the temperature control towards warmer. Like Chemair said, the compressor does cycle, but this is...

That's the fundamental insight I was missing. I can see why it is the case. Thanks!

The Gravitron is a fixture from my county fair childhood- just the thought experiment of moving around in there makes me queasy. I never had the right stuff. I remember hurling from it, though thankfully not inside the gravitron itself- my lunch came up on the cool down lap on the pirate ship!

My ability to work with vectors is poor I'll admit, but the simple answer seems to be no, right? It is not possible to make Ac zero by changing the angular velocity over time. And would this take into account the possibility of rotation around a separate axis, such as spinning around the radius...

It is often proposed that gravity could be simulated on a space station by rotating around an axis, such that the astronaut experiences the centripetal force of the space station wall, analogously to gravity. It is usually mentioned that the radius of rotation must be very large to avoid...