Thanks for the responses everyone. Maybe I gave a bum steer in bringing up Bell's inequality, what I'm after is an intuition as to what is incomplete/wrong with the analogy. Imagine someone had only encountered Quantum Physics at a "read New Scientist occasionally" level and came up with the...
Here's a simple story. I'm running a pizza delivery store and hit upon a gimmick to increase sales, I call it "Schrodiners Slice". You call up and get paired up with the next caller and your orders are randomly shuffled. Maybe you get your order, but maybe you get the next persons order instead...
How is this for a simple analogy;
You have to accept first that everything has a fixed total space-time velocity. Let's apply this to regular 3 dimensional space. Say you are traveling and 100 Km/h due east. Your total velocity is 100 km/h. Now let's say you turn a bit so that you are going...
Remember that the balloon analogy is just a device to help you understand the consequences, not the cause, of the expansion of the Universe. The Universe expands because everything is moving away from everything else, the initial motion having been kicked off by the Big Bang. The expansion slows...
GBB, it is not a question about the definition of what a galaxy is, but just whether that bunch of stars is a galaxy or something else. So it's not like say the 'is pluto a planet' kind of debate.
Basically we think bigger galaxies like the Milky Way form by the mergers of many many small dwarf...
I realize this is an old post, but since the thread has been bumped anyway...
The fact that a paper appears on arxiv really doesn't signify very much. It doesn't mean that it has been peer-reviewed. There is a level of moderation of arxiv postings, but it is not very strict. (That is in no way...
I haven't read that paper in detail, but from the abstract it is drawing physical significance from the properties of a particular co-ordinate system. This is a big no no! Anything with physical meaning will be invariant (not co-ordinate dependant). So for instance, you should be able to...
Write down the Stefan Boltzmann law. Think about the terms in the equation. Which one do you need to calculate, and which ones are you already given?
Note that because this is a homework question, I'm following the guidelines for answering homework from the Homework Help forum, rather than just...
Yes
Write down the definition of the matter density parameter \Omega_m. You should be able to find this in any textbook on the subject. From that definition you should see that if you specify the Hubble constant and the matter density parameter, then you will have a number for the physical...
You need to first consider how to calculate the energy density in radiation, given that you are told that it follows a black-body spectrum of a given temperature. That's the hardest part of this question. You shouldn't need to worry about the energy of a proton, if you assume a reasonable...
The power of telescopes isn't just in their size. In order to collect useful information, the receivers (the part that actually picks up the signal that has been focused by the dish part) have to have low noise, very accurate timing etc etc. These things are expensive and require a lot of...
It sounds like you are reading some slightly older material. At one point we classified the Universe under the simple 'open/flat/closed' system because we thought the only thing that mattered was the density of matter. If there is not enough, we have an open universe, too much we collapse and...
bjacoby, The Second Law of Thermodynamics is often wildly misunderstood. The simple description of it that 'order goes to disorder' leaves out the important point that this is true in a closed system. If you leave a disordered bunch of soil in isolation then it will not in general turn into a...
For anyone wanting to read the full article it can be found http://news.discovery.com/space/the-universe-is-precisely-1375-billion-years-old.html".
In answer to your question, it is a bit confusing as this pop-sci article doesn't mention enough specifics to know what it is referring to...
The problem with re-fueling is two-fold. The first is that rocket fuel needs to be highly processed and refined, so it's not just lying around in space. The second is that if you are moving at speed, and then run into a fuel source that is stationary, you will lose a bunch of your speed as...