Recent content by alphawolf50

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    What updates can we expect for the new PF website style?

    Aaahhh, you're running nginx as a cPanel plugin... I see it now. I didn't get the distinction between "nginx admin" and regular old "nginx". Too bad :-(
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    What updates can we expect for the new PF website style?

    I like! Next on the list: enable SSL :-) Guessing by the PTR record in DNS, physicsforums.com is already on a dedicated IP address... Just get one of the free SSL certs out there installed, and no longer will everyones' login credentials be passed "in the clear". A company called StartSSL...
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    Quantum Entanglement & Relativity: Time Dilation Effects

    I think I get the general idea of what you fine fellows are saying. Nearly everything I know of quantum mechanics comes from watching the Science Channel, and one program used a coin-tossing analogy to describe entanglement. It left the impression that, while each toss was random and you...
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    Quantum Entanglement & Relativity: Time Dilation Effects

    Are you saying entanglement is only good for one observation? If Alice sees "clockwise" on her first observation, she knows that Bob is counter-clockwise -- but if she observes her particle a second time she knows nothing of Bob's particle?
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    Can we use the Andromeda Paradox?

    Would it work better if I said "Bob and Alice each take a snapshot of spacetime from their unique frames of reference" ? I was attempting to rephrase what you said about designing coordinate systems where Bob is at rest, but apparently it was a poor rephrase :) The circle I'm talking about is...
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    Can we use the Andromeda Paradox?

    Hi JesseM, That makes sense. I had forgotten about the inertial/non-inertial reference frames. I just want to paraphrase what you said to make sure I actually understood :) Since Bob is accelerating, his frame of reference is non-inertial. But if we were to take snapshots of the...
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    Can we use the Andromeda Paradox?

    Hi Drakkith, Technically, everything we see with a telescope is "the past", specifically because the speed of light is finite :) But, yes, I believe you are correct if you're saying we can't see *further* into the past by moving our telescope away. However, in the context of the Andromeda...
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    Can we use the Andromeda Paradox?

    Thanks, Hurkyl. So basically this paradox requires you to have some manner of instantaneous "remote viewing" of Andromeda, rather than relying on light to travel across the universe and let you know what has happened?
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    Can we use the Andromeda Paradox?

    Can we "use" the Andromeda Paradox? Perhaps the term I should be using is "relativity of simultaneity"... anyway :) Usually I see the Andromeda Paradox stated in terms of a stationary observer and another who is moving toward the galaxy. I did find one source that said the reverse effect...
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    What is the difference between adding heat and adding cold?

    The opposite, "heating" with no temperature change is observed quite frequently, though most don't notice. Melting ice can absorb a lot of "heat" -- but just as the ice was 0 degrees C before the state change, the water is 0 degrees after. As long as the heating is slow and even, the ice/water...
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    Earth as return path for power transmission line?

    Ummm... Yes they do, in the case of Single Wire Earth Return transmissions systems, which was the topic of this thread.
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    Earth as return path for power transmission line?

    NEC standard is no more than 25 ohms resistance to ground. I realize this isn't the same as "resistance through the earth", which changes depending on moisture and mineral content along the path, but it at least gives you a starting point. Like OmCheeto said, yes, you can do it with DC -- in...
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    What is the difference between adding heat and adding cold?

    From the link: This baffles me -- how can radiation from a cold object cool another object? I'm familiar with laser cooling, but this sounds like a different animal. I haven't seen the setup, but I would venture to say they've got the causality reversed. IE, the mirrors are isolating...
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    Calculating Apparent Speeds of Objects at Light Speed

    Your friend is wrong :) If there are two ships, A and B, and they are traveling at .75c relative to a stationary observer C, then both A and B believe they are approaching the other at .96c. The formula is: v=\frac{w - u}{1 - wu/c^{2}} in other words (btw, since we're using "natural...
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    What is the difference between adding heat and adding cold?

    Simple, you add any amount of particles that are above 0K, and you've added an arbitrary amount of thermal energy to the space. On the other hand, if you fill that space with particles at 0K, it has the same thermal energy as it did before. "Heat" is a noun synonymous with thermal energy...
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