posted
I've been reading Hawking's Brief History of Time, and have been enjoying it very much. I tried to start with Einstien and went crosseyed before page 6; needless to say, Hawking has been a lot easier to read thus far. I have a tendency to read something, continue on, and then when I'm not doing anything, I think about things.
Well one of the things my mind jumped to was something Hawking wrote in the second chapter, which was that by the equation E = mc^2, the energy a object has due to it's motion will add to it's mass.
Over the years of just about any science class I ever slept through in high school, biology included, I came to believe that mass was a measure of matter, and something that was repeated every other day "matter/energy can not be created or destroyed, but can be changed."
So I'm confused now. If something is sped up, it then takes up more space? Or what?
Posts: 9754 | Registered: Jul 2002
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posted
In physics, the mass of an object is defined as a measure of the difficulty of accelerating the object. An object going faster will have more mass, meaning that increasing its speed will be harder.
In biology, saying that mass is a measure of matter is imprecise. It's really our physical world intuition of the physics concept of mass.
Thus, the law of thermodynamics is maintained, and there is no creation of new matter or energy.
I'm not certain about whether or not an object accelerated near to the speed of light will take up more space. (Even if there is no new matter created, the existing matter could be more spread out). There is a phenomena that I think has been measured called length contraction that finds that objects compress a very small amount when accelerated. Thus, an accelerated object should actually be contained in less space.
However, this presumes that we know what space is, and that it doesn't change much (whatever it is) when objects are accelerated.
Posts: 338 | Registered: Jan 2001
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posted
Ok, so if mass is the measure of the difficulty of accelerating the object, then yeah, it makes sense. It's going to take more energy to move an object faster. Ok, that makes sense. It then explains that an object can not go faster than the speed of light, because then it's mass would be infinite, and impossible to accelerate any faster.
Ok, makes sense. If mass is all about the difficulty in moving something, it's simple to know. How then did I come to think that mass has to do with matter and space thats filled? This probably explains why I got a B- in most science classes.
Posts: 9754 | Registered: Jul 2002
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posted
Your first notion of mass is what is usually presented as our common-sense/intution of mass, and it is what it is usually defined as in at least lower biology course textbooks.
Posts: 338 | Registered: Jan 2001
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posted
Interestingly enough, most of the mass in ordinary matter is due to the energy of all the little sub-atomic particles whizzing around each other. So, mass isn't just what makes things hard to accelerate. It is also what makes things attract each other through gravity.
posted
I read A Brief History of Time a few years ago (also as a non-scientist), and I really enjoyed it as well. But it definitely gave me several headaches! Posts: 952 | Registered: Jun 2005
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Another factoid: Hawking was told that every additional equation would reduce his readership by a huge amount. So he only included 2-3 equations in his book...
Posts: 6316 | Registered: Jun 2003
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quote:Originally posted by Morbo: Another factoid: Hawking was told that every additional equation would reduce his readership by a huge amount. So he only included 2-3 equations in his book...
And it is one of the best selling pure science books...
posted
So if M is the measure of mass readership, and E is the number of equations, then C would be the cerebral appetite of the book buying public, such that:
quote:Originally posted by Teshi: I love A Brief History of Time! It lives on my bedside table.
Me too! Mine too!
quote:Originally posted by Dan_raven: Compared to Romance novels wich are 100% formula.
I mentioned this to Sharpie, and she said it just proves the phenomenon is more complicated than we thought -- perhaps a disjoint parabola -- or perhaps it is not the number of equations, but the proportion that is formulas. From 1 to 500 equations, readership drops from 10 million to 20, but at 100% formula it goes back up to 10 million....
Ha, ha, way to kill a joke, jvp
Posts: 431 | Registered: Oct 2003
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I remember reading A Brief History of Time the summer before my freshman year of high school, and I really enjoyed it. I want to re-read it someday, but I have a mile-long list of books I've never read that I want to get through first.
Posts: 45 | Registered: Jun 2000
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I was just reading the new Wheel of Time book that just came out so the first thing i though of when i saw this topic was Arthur Hawking? What can u read of his?
Then I reallized who it was actually talking about....
Posts: 832 | Registered: Jan 2005
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Ha, ha, way to kill a joke, jvp
