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07/21/2008 03:06:10 PM · #76 |
Originally posted by togtog:
Sun->Oil->Fuel->Combustion->Propulsion->Momentum->Friction->Heat->Nikon->Ponies |
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Silly photographer, it's "Canons" that produce heat! |
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07/21/2008 03:14:50 PM · #77 |
Really off my OP but...
When all the Exergy is burned off...(when the whole universe goes dark) isn't all the "stuff" left over...even though not burning...become "potential energy"? (this must be true if energy can't be created or destroyed...only change forms).
If -- and this is a big if....If there is not enough matter in the universe to pull together into another big bang...then that's it...the universe sits forever dark.
However, if there is enough matter then everything (all the potential energy in a mass) begins to come together until it explodes again into another big universe.
Am I close?
Originally posted by SamDoe1:
The brakes of a car turn the kinetic energy provided by combustion of the fuel (potential energy) which when ignited turns into heat energy and is then rapidly expanded to produce the kinetic energy used to propel your car into heat energy by way of friction and dissipating it to the surrounding air.
Returning to the OP
The "scientific" way of explaining to your friend about why he's very wrong is through the idea of exergy. Exergy is the "usefulness" of energy. Energy is conserved, we all know that, but in any REAL process exergy is destroyed. This, in turn, means that there is a limited amount of exergy in the universe and after it is all used up...well that's beyond my means of understanding. Either way, when you burn fuel to run your car, you are destroying part of the exergy in the process because it is dissipating to other sources than the one you want to use. For example, the desired effect of burning the fuel in your car is to heat and rapidly expand the air in the cylinders to achieve the desired effect of force on the piston downwards (or sideways if you have a subaru and/or porsche) which in turn drives the crankshaft and your car moves. However, part of the useful energy is lost by means of heat which is not the desired effect. In order to improve the overall exergy efficiency the heat energy lost can be used to, for example, heat your car (making it useful) which is regeneration. Regeneration is used all the time in power generation cycles in order to improve exergy efficiency.
In the means of one battery to drive a car and the motion of the car to charge the other one, there is exergy loss in that cycle. That means that it will not work because there is not a 100% power recovery. If 100% of the energy was conserved WITHIN the cycle, you would have a reversible cycle and that is impossible.
I love thermodynamics! Don't you?
PS: If any of you manages to invent a process where exergy is not destroyed, let me know. I will invest heavily... |
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07/21/2008 03:20:01 PM · #78 |
| You all might want to read Isaac Asimov's story The Last Question, which addresses the issue of universal entropy in detail ... |
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07/21/2008 03:23:36 PM · #79 |
Originally posted by kenskid:
Really off my OP but...
When all the Exergy is burned off...(when the whole universe goes dark) isn't all the "stuff" left over...even though not burning...become "potential energy"? (this must be true if energy can't be created or destroyed...only change forms).
If -- and this is a big if....If there is not enough matter in the universe to pull together into another big bang...then that's it...the universe sits forever dark.
However, if there is enough matter then everything (all the potential energy in a mass) begins to come together until it explodes again into another big universe.
Am I close?
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Well from what I learned from my thermo class...yes. At least that was my understanding.
When all the exergy in the universe is used up, all that is left is entropy. At this point, particles in the universe are so far apart from each other that they cannot interact with each other. When this occurs, everything collapses and you have another big bang and the process starts over. This is similar to what happens to stars when they grow to red giants. They collapse in on themselves and, if there's enough mass, go super nova.
Message edited by author 2008-07-21 15:27:57.
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07/21/2008 03:28:39 PM · #80 |
Originally posted by SamDoe1:
When all the exergy in the universe is used up, all that is left is entropy. At this point, particles in the universe are so far apart from each other that they cannot interact with each other. When this occurs, everything collapses and you have another big bang and the process starts over. |
That would be the Cyclical theory ... not in fashion right now as I understand it. If the particles "can't interact with each other" there is nothing to cause them to collapse back into a new Cosmic Egg and trigger a new big bang. Hopefully,none of us will be around to find out which theory is correct ... ;-) |
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07/21/2008 03:49:46 PM · #81 |
Originally posted by GeneralE:
That would be the Cyclical theory ... not in fashion right now as I understand it. If the particles "can't interact with each other" there is nothing to cause them to collapse back into a new Cosmic Egg and trigger a new big bang. Hopefully,none of us will be around to find out which theory is correct ... ;-) |
Maybe... I don't know enough about that topic to have a real answer.
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07/21/2008 03:53:45 PM · #82 |
Originally posted by GeneralE:
Originally posted by SamDoe1:
When all the exergy in the universe is used up, all that is left is entropy. At this point, particles in the universe are so far apart from each other that they cannot interact with each other. When this occurs, everything collapses and you have another big bang and the process starts over. |
That would be the Cyclical theory ... not in fashion right now as I understand it. If the particles "can't interact with each other" there is nothing to cause them to collapse back into a new Cosmic Egg and trigger a new big bang. Hopefully,none of us will be around to find out which theory is correct ... ;-) |
Reminds me of this little exchange from one of my favorite films:
Dr. Egon Spengler: There's something very important I forgot to tell you.
Dr. Peter Venkman: What?
Dr. Egon Spengler: Don't cross the streams.
Dr. Peter Venkman: Why?
Dr. Egon Spengler: It would be bad.
Dr. Peter Venkman: I'm a little fuzzy on the whole "good/bad" thing here. What do you mean, "bad"?
Dr. Egon Spengler: Try to imagine all life as you know it stopping instantaneously and every molecule in your body exploding at the speed of light.
Dr. Ray Stantz: Total protonic reversal!
Dr. Peter Venkman: That's bad. Okay. All right, important safety tip. Thanks, Egon.
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07/21/2008 03:58:27 PM · #83 |
| Doesn't gravity however faint span the universe? It would seem to me that even the smallest amount of drag back towards the center would eventually cause all matter to stop moving outwards, then inwards. I think I remember something about dark or pony matter effecting this somehow and making the expansion speed up? |
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07/21/2008 04:06:32 PM · #84 |
The current thinking is that there is not enough "visible" matter to pull everything back together. In other words, the force of the big bang exceeded the force of gravity and will expand forever or stop.
However, I'm pretty sure scientist have located dark matter and currently think there is enough for a "big crunch".
Originally posted by togtog:
Doesn't gravity however faint span the universe? It would seem to me that even the smallest amount of drag back towards the center would eventually cause all matter to stop moving outwards, then inwards. I think I remember something about dark or pony matter effecting this somehow and making the expansion speed up? |
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07/21/2008 05:31:23 PM · #85 |
Originally posted by kenskid:
The current thinking is that there is not enough "visible" matter to pull everything back together. In other words, the force of the big bang exceeded the force of gravity and will expand forever or stop.
However, I'm pretty sure scientist have located dark matter and currently think there is enough for a "big crunch".
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"Determining the nature of this missing mass is one of the most important problems in modern cosmology and particle physics. It has been noted that the names "dark matter" and "dark energy" serve mainly as expressions of human ignorance, much as the marking of early maps with "terra incognita."
:-P LOL
wiki |
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07/21/2008 05:37:19 PM · #86 |
Maybe we'll soon have first hand experience with the big bang....
LHC Countdown
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07/21/2008 05:41:53 PM · #87 |
Could be called ingorance but isn't the talk of dark matter a theroy to support the "big crunch" theroy? In other words, in order to support the theroy of a never ending cycle of big bang/big crunch universes, scientists say they "need more matter"? Without the matter, then the "crunch" does not occur.
So if one believes in the big crunch then they must believe there is matter out there that simply can't be seen or registered by our currently technology. However, I think progress has been made in the area of seeing dark matter by seeing it's effects on other matter. This is the same as deducing that plants are revolving around other suns by registering the "tug" or clockwork wobble of a distant sun.
Originally posted by thegrandwazoo:
Originally posted by kenskid:
The current thinking is that there is not enough "visible" matter to pull everything back together. In other words, the force of the big bang exceeded the force of gravity and will expand forever or stop.
However, I'm pretty sure scientist have located dark matter and currently think there is enough for a "big crunch".
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"Determining the nature of this missing mass is one of the most important problems in modern cosmology and particle physics. It has been noted that the names "dark matter" and "dark energy" serve mainly as expressions of human ignorance, much as the marking of early maps with "terra incognita."
:-P LOL
wiki |
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07/21/2008 05:50:46 PM · #88 |
I believe the 4 predominate theories are "The big Crunch", "Heat Death" "The big rip" and "The big bounce"
In regards to the "The big crunch" here is a sliver from wiki:
"Recent experimental evidence (namely the observation of distant supernovae as standard candles, and the well-resolved mapping of the cosmic microwave background) have shown that the expansion of the universe is not being slowed down by gravity but rather accelerating. However, since the nature of the dark energy that drives the acceleration is unknown, it is still possible that it might eventually reverse sign and cause a rapid collapse."
So we are not sure. Maybe when they get this bad boy up and running they might be able to decide on one.
:-)
ETA: David beat me with the LHC post! :-D I can't wait to see what the CERN images look like!
Message edited by author 2008-07-21 18:20:42. |
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07/21/2008 05:55:30 PM · #89 |
According to the Science Channel series Time the Universe will continue to expand, the last of the stars will burn out, then billions of years later matter will devolve until only atoms are left, and then continue till only sub atomic particles are left. At that point there will not be enough gravity in any one spot to pull everything back together for another bang.
The show was part of the series on time, and the episode discussed whether time would eventually come to an end.
According to them, no because the sub atomic particles would continue to zip around.
How much smarter the scientists they talked to are than any others is open, I'm sure, to debate.
Seems a sad way for it to all end. If the big bang were to happen over an over, that would be more satisfying to me. |
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07/21/2008 06:16:31 PM · #90 |
Originally posted by kenskid:
Could be called ingorance but isn't the talk of dark matter a theroy to support the "big crunch" theroy? In other words, in order to support the theroy of a never ending cycle of big bang/big crunch universes, scientists say they "need more matter"? Without the matter, then the "crunch" does not occur. |
No, in fact there is ample physical evidence for dark matter. Though we are pretty much ignorant of the nature of dark matter, its effects can be observed (think gravitational lensing for instance) and its distribution even crudely mapped. There is still not enough matter, apparently, for the universe to stop expanding. A reversal and "big crunch" seems at this point to be an unlikely possibility. |
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07/21/2008 09:46:43 PM · #91 |
Hmmm..
We're pretty sure that a big bang occured. It is just about proved that the universe is expanding. If it is expanding then it makes sense that it was once "a point".
So...if there is not enough matter to bring it back "together" then how did it get "together" the first time..(our current start of the universe)?
Is this where "God" comes in? Is God the creator of the first and only and DYING universe?
Originally posted by kirbic:
Originally posted by kenskid:
Could be called ingorance but isn't the talk of dark matter a theroy to support the "big crunch" theroy? In other words, in order to support the theroy of a never ending cycle of big bang/big crunch universes, scientists say they "need more matter"? Without the matter, then the "crunch" does not occur. |
No, in fact there is ample physical evidence for dark matter. Though we are pretty much ignorant of the nature of dark matter, its effects can be observed (think gravitational lensing for instance) and its distribution even crudely mapped. There is still not enough matter, apparently, for the universe to stop expanding. A reversal and "big crunch" seems at this point to be an unlikely possibility. |
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07/21/2008 10:13:44 PM · #92 |
| There is the big bang, this creates the universe and god, god creates man, man evolves and explores the universe, man creates a better god, god goes back in time and creates big bang... |
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02/13/2009 12:08:19 PM · #93 |
Hello,
I had a discussion today with someone.
They said that there is surely a way to build a car that runs completly on battery power. They said it would have two batteries. As one battery powered the car, the other would get charged up from power generated by the turning wheels.
I said that is possible but in a short time both batteries would drain and need to be recharged by an external power supply. The other guy said "no it wouldn't". He says that the turning wheels would always charge the "other" battery and it would run basically "forever".
He feels that this car could be built but oil companies would crush it's development for obvious reasons.
I have a Biology Degree that included 4 semiesters of of physics. To have his theroy work would mean a complete breakdown of the thermodynamic laws.
What do you think...am I right?
Why donĂ¢€™t they put a Perpetual motion charging system in a vehicle, and there will not need to be so many batteries required to run the car? This will increase the mileage of a vehicle to the point that we do not need a recharge. |
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02/13/2009 12:22:04 PM · #94 |
Originally posted by RadDad:
Hello,
I had a discussion today with someone.
They said that there is surely a way to build a car that runs completly on battery power. They said it would have two batteries. As one battery powered the car, the other would get charged up from power generated by the turning wheels.
I said that is possible but in a short time both batteries would drain and need to be recharged by an external power supply. The other guy said "no it wouldn't". He says that the turning wheels would always charge the "other" battery and it would run basically "forever".
He feels that this car could be built but oil companies would crush it's development for obvious reasons.
I have a Biology Degree that included 4 semiesters of of physics. To have his theroy work would mean a complete breakdown of the thermodynamic laws.
What do you think...am I right?
Why donĂ¢€™t they put a Perpetual motion charging system in a vehicle, and there will not need to be so many batteries required to run the car? This will increase the mileage of a vehicle to the point that we do not need a recharge. |
The car would be a closed system. Any energy lost to heat, noise, etc, would have to be replaced from outside that system; i.e. with gasoline.
You are absolutely correct that it would violate the laws of thermdynamics, and dramatically so.
Edit to say - just realized I was responding to what was essentially a repost of the original message in this thread. It's been covered.
Message edited by author 2009-02-13 12:24:35. |
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02/13/2009 12:25:58 PM · #95 |
Originally posted by RadDad:
Hello,
I had a discussion today with someone.
They said that there is surely a way to build a car that runs completly on battery power. They said it would have two batteries. As one battery powered the car, the other would get charged up from power generated by the turning wheels.
I said that is possible but in a short time both batteries would drain and need to be recharged by an external power supply. The other guy said "no it wouldn't". He says that the turning wheels would always charge the "other" battery and it would run basically "forever".
He feels that this car could be built but oil companies would crush it's development for obvious reasons.
I have a Biology Degree that included 4 semiesters of of physics. To have his theroy work would mean a complete breakdown of the thermodynamic laws.
What do you think...am I right?
Why donĂ¢€™t they put a Perpetual motion charging system in a vehicle, and there will not need to be so many batteries required to run the car? This will increase the mileage of a vehicle to the point that we do not need a recharge. |
In a perfect world full of 100% efficient transfer of energy along with an absence of friction and air resistance, your friend would be correct.
In the real world, full of losses due to energy conversion, friction and a host of other less that perfect things, his idea is completely bogus. |
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02/13/2009 12:46:26 PM · #96 |
Originally posted by Spazmo99:
In a perfect world full of 100% efficient transfer of energy along with an absence of friction and air resistance, your friend would be correct. |
Kind of - if there were any change in potential energy (i.e. going up a hill) it wouldn't work. So in a 100% flat, frictionless world, sure... Though without friction your tires wouldn't work.
Typical automobiles operate around 15% fuel-to-wheel efficiency; that is, 15% of the energy contained in the fuel actually goes to turning the wheels; the rest is consumed internally (which is why your motor gets hot). That's before air friction, rolling resistance, etc. So reclaiming 10% of what you put it would be a major achievement. |
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02/13/2009 01:08:02 PM · #97 |
Sorry to be a bit off-topic, but I wanted to mention this...
Originally posted by jrhendri:
... I keep my tires at max pressure given on the sidewalls... |
Correct tire pressure does help with gas mileage, but my understanding is that tires are to be inflated to the recommended pressure indicated on the car, as the engineers/designers intended. A tire's max pressure may or may not match what the specific car model calls for, and the wrong inflation could affect handling, or shorten the life of your tires.
scroll down to see part 3
wikipedia tire pressure
Message edited by author 2009-02-13 13:09:29. |
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02/13/2009 01:18:46 PM · #98 |
What the heck? This thread is a year old and got resurrected by a 1-time poster with the exact verbage of the original post?
Sorta twilight zone-y. Maybe the question is actually a homework assignment from a textbook which led to the same wording? |
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02/13/2009 01:34:29 PM · #99 |
| D'oh! I didn't check the dates of the thread... |
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02/13/2009 01:39:25 PM · #100 |
Originally posted by DrAchoo:
What the heck? This thread is a year old and got resurrected by a 1-time poster with the exact verbage of the original post?
Sorta twilight zone-y. Maybe the question is actually a homework assignment from a textbook which led to the same wording? |
Unlikely that the typos were from the homework - it's a cut-and-paste job. Oh well, I like talking physics. |
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