Tag: entropy

More on Entropy, but not a fight over it! (yet)

Question from Keisha:

Thanks for “Entropy 101”. It helped me a lot. Are you saying that the sun has an infinite amount of “fuel” ?



Answer by SmartLX:

A lot of fuel, but not an infinite amount.

What the sun has is a vast amount of hydrogen, which burns in constant nuclear fusion and thus fuses together to make helium. It will take about 5 billion years (it’s had 5 billion already) but eventually all the hydrogen will be helium and that specific reaction will no longer occur. The helium will start burning but the reaction will be different and not sustainable, which is why the sun will become a red giant and ultimately shrink to a white dwarf. We’ll all be gone long before then, whether we’ve found a way to escape the solar system or just perished right here.

My point earlier was that as long as the sun burns, it’s an unfathomably huge rate of entropy – “loss of order” – which balances out almost any emergence of order that could possibly happen on Earth. Regardless of the exact mechanics of that process, it’s in no danger of violating the Second Law of Thermodynamics.

Theist Cosmology: As Long As God’s Necessary Somewhere

Question from Physitheist:
I’m going to start this by saying that I’m a Christian, but also someone who believes in science…Here’s my question. According to the laws of thermodynamics energy moves to heat. Also there is no process that is truly reversible because we can not reach absolute zero, and the process would take infinite time. Since entropy continues to increase, and there is a limit of mass and energy how are we here? If there is not a limit of energy and mass, then why do you think so? And if you believe that energy and mass can appear out of thin air balanced out by anti matter why haven’t we ever seen this? After all the amount of unusable heat created is enormous. So basically my question is this, given the laws of thermodynamics, if you extrapolate to the size of the universe how are we here? After all the Big Crunch theory doesn’t really solve the energy problem since no process is 100 percent efficient. We’d still only have heat since there’s no such thing as negligible when the scale is eternity.

Thank you, and have a wonderful day!

Jesus loves you!

Answer by SmartLX:
I answered a similar question in my piece The World of Leftover Energy, so you can comment on that one if you like. Here I’ll just try to address some of your specific points and questions.

If you extrapolate the laws of thermodynamics regarding entropy to account for the entire universe they need to be applied as to a closed system, because we’re not aware of any energy leaving the universe. A hypothetical Big Crunch takes all the matter and energy there has ever been and jams it back together in a singularity – even the “lost” energy that’s been radiated outwards throughout the history of the compressed universe. That could actually achieve 100% efficiency through recycling, as literally no energy would be lost and the singularity could behave exactly the same as the previous singularity.

There is most likely a finite amount of matter and energy in THIS universe. If it’s the only universe, an eternal existence would have to depend on some form of reclamation, like the Big Crunch, or an exponential decrease that never hits zero, like I describe in the other piece. If there are other universes, as many have theorised and some evidence actively suggests, then it’s very possible that the total matter and energy in the multiverse is infinite, and entropy doesn’t mean much on the grand scale. I don’t feel the need to declare one or the other scenario more likely. An eternal universe isn’t certain in the first place, but a non-eternal universe doesn’t guarantee an eternal creator god.

Think about what would happen if a small group of matching matter and antimatter particles suddenly emerged naturally somewhere on Earth, and therefore in an environment saturated with existing particles of matter (e.g. air, water or earth). The antimatter would be annihilated by the existing matter in an instant, and the matter it touched would also be annihilated, so you’d be left with no antimatter and exactly the amount of matter you started with. It could be happening all around us and we’d never detect it without precise instruments. This isn’t proof that it happens, but it makes it impossible to say that it isn’t happening.

The World of Leftover Energy

Question from Andrew:
Why do atheists like Stenger say that the universe can be eternal, when this does not hold?

Stenger argues that the universe can be eternal, non-created, extrapolating the law of conservation of energy-mass before the planck time, he says that because we do not see a violation to this law, the universe can perfectly be eternal.

But this is a fallacy as William Lane Craig exposed once. If the energy were eternal there would be no useful energy right now, it would have become useless, complete entropy an infinite time ago, and because we do not see this, the only conclusion is that the universe and the energy began a finite time ago. Where we Christians think, the best explanation is the creation by God.

Answer by SmartLX:
Even according to you, Stenger only said the universe can be eternal, not that it definitely is. If it isn’t, then God is only one possibility among who knows how many: spontaneous emergence (more on that in a sec), a previous universe, a deistic rather than theistic (let alone Christian) god and so on.

Anyway, there are at least three straightforward ways in which there can still be useful energy now after an eternity of existence. There might be others, but even one possible way is enough to keep someone like Craig from ruling out the possibility entirely.

1. There is infinite or potentially infinite energy as well as infinite time.
Our universe as we see it has existed for a finite amount of time since the Big Bang with a certain amount of matter and energy, but what if that only contained one portion of the available material of an endless universe or multiverse? Or can matter emerge regularly and spontaneously from the quantum foam as much as it likes, as long as the same amount of antimatter accompanies it and the total amount of “positive” energy stays constant? As Lawrence Krauss says, something can come from nothing if “nothing” is unstable.

2. The energy is periodically reclaimed.
Entropy doesn’t destroy energy (hence Stenger’s point), it only ends up radiating it towards the edges of the universe where it’s no use to anyone. If Big Bangs are regular rather than one-off occurrences, then there’s a long-standing hypothesis that the universe is first drawn together in a Big Crunch. The new singularity contains not only all the matter and energy of the crushed universe, but all the space as well. Whatever was lost to entropy is dragged back to a mathematical point, just like at the point of our own Big Bang, and the cycle can begin again.

3. The amount of available energy decreases exponentially.
The less energy there is, the slower it dissipates, the way a gush becomes a trickle when you tip out a bucket of water. Say that every billion years, the amount of available energy decreases by half. If so then a billion years ago there was twice as much, and two billion years from now there’ll be a quarter as much, but there will never, ever be none. It will approach zero (or, importantly, a non-zero constant) asymptotically, which is to say it will get closer and closer without ever reaching it. Perhaps the amount of energy we’re used to seeing in the world is practically nothing compared to the intense heat, light and motion that was everywhere in times gone by, with the universe in a state of near-saturation (perhaps asymptotically again). Without past reference points from before the Big Bang, which are probably impossible to attain, you can’t make a judgement that there can’t be this much energy now.

One final point: be very careful about expressions like “the best explanation” when discussing cosmology. If quantum mechanics have taught us anything, it’s that reality can be counter-intuitive, and the truth might well strike one as ridiculous. If there’s evidence for a claim then it’s a supportable claim, but if all it does is sound right then it’s worthless.

Entropy 101

Question from Jack (reproduced from a comment in the archive):
I’ve spent some time reading about evolution and creation. I’ve read several pages about entropy and I can’t seem to find one that makes sense. Can you explain entropy to a poor retard like myself?

Answer by SmartLX:
It’s a difficult concept, and most of us have to make do with an approximation, so here’s mine.

Imagine the process by which objects with some physical order (structure, symmetry, smoothness, etc.) break down over time (decay, melt, crumble, evaporate, rot) into substances which do not have that initial order (powder, gases, liquids, mush). They’re moving from an ordered state towards a more and more unordered state. Entropy, as a quantity, is the extent to which this has already happened at any given time. About the closest thing to a synonym for it is “loss of order”.

If entropy increases, order has been lost. If it decreases, order has emerged or been created. The point of the Second Law of Thermodynamics is that entropy can’t decrease without increasing by at least as much in some connected object or area. In other words, it can’t decrease overall in a closed system.

The corrupted version of this law used by creationists is effectively that entropy can’t decrease at all without divine help. Alternatively they accept the law, but claim that the Earth is a closed system and any fresh order on it must be gods’ work. The response to the latter is to point out that the sun is part of any closed system which includes us. The thing runs on explosions, causing massive amounts of entropy. It sends some of the resulting energy our way as light, heat and radiation so that we might undo a tiny fraction of that entropy. That’s the connection.

A more general response is that if you think entropy is decreasing in a closed system, it’s likely that the system is not really closed.