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Physics, Astronomy & Cosmology / Re: How does mass increase at higher speeds?

« on: 11/12/2012 10:09:21 »

These are not independant things. Mass is the measure of something's inertia.

But mass creates a gravitational field. Whereas inertia doesn't, in my opinion. That's the distinction I'm referring to. Mass also implies the amount of "stuff" (or matter) whereas inertia is just resistance to a force. So does that mean that things moving near the speed of light have a larger gravitational field than they would otherwise? Maybe it would normally be negligible but the whole point of science is to be accurate.

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Physics, Astronomy & Cosmology / Re: Point of maximum gravity/pressure inside a planet or star

« on: 05/12/2012 12:26:37 »

Okay, so the net force at any point is always toward the center, but near the center, that net force becomes small (or even zero). Does that have any significant implications? And is the pressure maximum at the very center or somewhere further out where the net force due to gravity is larger (or even maximum)?

And yes, I figured out that technically gravity should be integrated over all the bodies involved but planets and stars were always simplified to a point when I was taught (in high school), which is perfectly accurate for most applications. But when is the difference between the two versions no longer negligible? How close do two bodies have to be before their sizes become relevant?

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Physics, Astronomy & Cosmology / Re: Are relativity equations compliant with the energy/mass conservation principle?

« on: 05/12/2012 06:41:12 »

I'm not an expert but yes, I'm pretty sure it all works out perfectly. For example, let's say a spaceship is moving "near" the speed of light. Then you could measure its kinetic energy, using its apparant mass (or inertia) instead of its rest mass. This will tell you exactly how much work/energy has been put into moving the spaceship. If it weren't for relativity, the spaceship would be moving faster instead of "weighing" extra, but either way, the energy's the same. That's also exactly how much work/energy it would take to slow it down. So basically, none of the work is wasted. Please correct me if I'm wrong about this!

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Physics, Astronomy & Cosmology / Re: Why do we assume the Big Bang was the beginning of everything?

« on: 05/12/2012 06:23:06 »

Okay thanks. But I thought it was a really common view that the Big Bang was *the* start. And as soon as you ask about the beginning of the universe, people say the Big Bang, as if that's a full explanation, when they should say, well there was that Big Bang which happened, but other than that, we have no idea. In my opinion it's a huge distinction that gets palmed off as if it doesn't really matter.

About the multiverse, I meant that the word "universe" is supposed to be EVERYTHING by definition. So the multiverse is just the universe. Doesn't matter if it has 100 dimensions and/or infinitely many parallel "universes" (whatever that means), it's still the universe. The same as atoms were meant to be the smallest indivisible objects. Why do we keep going on wild goose chases? Maybe there's no smallest, no biggest, no beginning. Then everyone can relax and stop looking for some ultimate theory of everything.

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Physics, Astronomy & Cosmology / Re: How does mass increase at higher speeds?

« on: 05/12/2012 06:14:51 »

I vote that it's actually inertia which increases, not mass. To say mass is incredibly misleading, in my opinion. And the inertia doesn't *really* increase, it's just that there's kind of a gap between two perspectives moving very fast relative to eachother. They disagree about time flow which results in these weird effects, like objects seeming heavier and harder to push than usual. It's because in a sense they're moving faster than they appear, so the rest of that momentum goes into this apparant "weight".

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Physics, Astronomy & Cosmology / Re: Why is life not common in our galaxy?

« on: 05/12/2012 02:01:47 »

Unless I'm mistaken, this is one of the things in science we know least about. Life could be incredibly abundant or it could be rare to the point that we are completely alone. We have no context so we don't know how natural it was for life to arise here. Maybe it's inevitable for any "habitable" planet or maybe this is the only place it has ever occured.

Nor does life necessarily lead directly to "intelligent" life, they may be two independently amazing miracles. Obviously, if "intelligent" aliens are deliberately putting out messages they'll be easier to detect. What's interesting to me is the pace of our own evolution. Has it been a fairly steady, linear path? As in, was there much chance involved or was it always going to take exactly this long for us to reach this point?

It seems silly to be worried about a lack of life (or evidence for it) seeing as we literally just exploded onto the scene and have just barely started to scratch the surface of exploring the universe. What happened here was clearly quite special or else we would have popped onto the scene long ago. And considering our pace of technological progress, we'll know soon enough. Consider all the millions of years of dinosaurs eating eachother. We've got time. If other life exists, they're most definitely *way* ahead or *way* behind us.

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Physics, Astronomy & Cosmology / Where is the point of maximum gravity inside a planet or star?

« on: 05/12/2012 01:16:56 »

We always treat gravity as attracting things to the *center* (of gravity) of a planet or star, for instance let's consider one called Plar. But if you were *inside* Plar, it would be different. At the center, you would be pulled out in every direction right? So do those forces simply cancel out and you feel nothing or do they create a tension that pulls things apart? I lean towards the first one.

In that case, where is the net force due to gravity maximum? How far into the center? And also, where is the "pressure" maximum from all the stuff sitting on top of you? Is it still the center because it all adds up from the higher material?

You can assume Plar is homogenous if that helps, surely it can be figured out with some calculus, but I'd also be interested in Earth. Finally, does this phenomenon have any noticeable effects, like on the nuclear reactions in stars or can a hole form from material being pulled out?

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Physics, Astronomy & Cosmology / Why do we assume the Big Bang was the beginning of everything?

« on: 04/12/2012 09:23:28 »

Hi, I'm new and have a bunch of questions, this is my first one. Hope you can help!

So there's plenty of evidence of a huge explosion/expansion 13.7 thousand million years ago. But what makes us think it was the beginning of EVERYTHING. Couldn't it have merely been *a* big bang caused by something? Couldn't the Big Bang turn out to be relatively tiny compared to the actual entire universe? How do we know that there is nothing behind the CMBR? And isn't this analogous to our previously supposing that the Earth was the centre of the solar system (and indeed the universe)?

Also, in my opinion, just because we discovered a cataclysmic event, doesn't mean it's the answer to all of our questions about our origins. Science can never answer philosophical questions.

Side question: Isn't it illogical to mention something like a multiverse when that goes against the notion of *the* universe? In a similar fashion to how atoms are made up of smaller things so that their name no longer seems appropriate?

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Physics, Astronomy & Cosmology / Re: Is there a googol of anything?

« on: 04/12/2012 00:03:14 »

I notice a pattern here...

It seems that if you're talking about physical objects then no, there isn't a googol of anything in the observable universe (except maybe strings or other small enough quantum things). But if you allow numbers of combinations, it's quite common and there are much bigger numbers as well.