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    CMB a picture of the past

    Hi, Am I right when I say that the cosmic microwave background is a picture of the radiation left from recombination but that the picture (from COBE or WMAP) that we see today is not exactly the same as it was then due to the redshifting of the radiation particles. The flucuations that we see...
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    Big bang predictions

    Hi, I am trying to understand how it is possible to make predictions about the energy density of early universe using the freidman equation if the expansion rate of the universe has not been constant throughout history. As I understand it there are three main variables in the freidman...
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    Proton / neutron freeze out

    As I understand it, it can be calculated that 1 minute after the big bang, when protons and neutrons freeze out and are no longer being created, that for every neutron that exists there are 7 protons. Does anyone know what equation is used to calculate this and if it is not a equation that is...
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    Expanding Universe

    Hello, I am trying to understand that in order for the universe to be expanding that galaxies at further distances must be moving away from us at faster speeds than galaxies closer to us. It seems enough that all galaxies are moving away from us (or each other if observed from another galaxy)...
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    More Density = More Gravity?

    Hi, I am a bit confused with how a neutron star or black hole has such a high force of gravity. As I understand the process of star death of a massive star (I'll use a neutron star for example), 1) the star fuses heavier and heavier elements 2) the core begins to contract 3) this...
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    Particle confusion

    So I have just started learning a bit about particle physics and I am confused about some small details... As I understood it fermions and bosons are two different types of particles that have different behaviours. They are not related other than the fact that they are both particles. But...
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    Nm into Joules

    Maybe this is a stupid question but... If I have a torque value of, let's say, 100 Nm, am I right in saying that it takes 100 Joules of energy to generate that torque since 1 Nm = 1 Joule.
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    Deadhang Equation

    Hi, I am working on a small project and am hoping to get some outside insight from anyone who has the time or intrest... One of my hobbies is rock climbing and because I am quite fanatic about it I train for it quite regularly. One of the methods commonly used for training is called 'dead...
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    Torque force homework help

    Homework Statement A drawbridge to the castle is slowly lifted. Its weight is 500kg. There are is one chain drawn over a pulley that pulls up the drawbridge (see pic). The angle is 30 degrees at the rotation point (see pic). link to pic if it dosen't come up...