pepperlandgirl

My philosophy teacher (who is also a Christian Minister) holds tight the theory that "God Did It" because he can't fathom the Big Bang.
I told him I can't debate him about it, because I know nothing about the Big Bang. Mainly because I don't care. I mean, I care about science, but I care more about evolution than the origin of the Universe. I'm weird like that.
Anyway, can someone give me a fairly simple explanation so I am at least armed with something the next time this discussion starts?

Also, is energy alive?

Francois Tremblay

No. Only entities can be alive. Energy is a property of an entity, not an entity (expressed more simply, energy is not an object but "belongs to" an object).

There are many kinds of energy : mechanical, kinetic, electrical, thermal, electromagnetic, chemical, entropic, etc. In all cases, they refer to the capacity of some entity or some system to do a quantity of work (as defined in physics).

This is a pretty basic definition but I hope it helps. I can't really help you about the Big Bang, because I don't know cosmology that much. All I know is that it was an expansion where primordial matter formed itself into lumps that became the galaxies and planets that we know today. I guess this alone should be enough to debate most religious people, as they don't know diddly-squat about science.

If the point of contention is about "how did the Big Bang happen... if we don't know, then God did it", that oft-repeated objection has three fatal philosophical flaws.

1. It is a meaningless choice to choose "no universe" rather than "universe" as a necessary starting point, and then posit "God did it". Only science can give us the answer.
2. Since there is no evidence of gods, it is more unreasonable to posit God as the cause than the universe itself (Occam's Razor).
3. It is meaningless to speak of a "before" to time, since time by definition passes only when it exists. Divine creation of time is impossible because any action requires time.

Hope this helps also.

[ March 07, 2002: Message edited by: Franc28 ]</p>

ohwilleke

Recall that this is a philosophy class, not a science class. It is entirely reasonable to ask "what should alive mean?" in the context of philosohpy.

To provide a similar philosophical question, how many organisms is a bee hive? Is it one for each bee, or is the hive itself a single organism? There are good philosophical arguments for both positions. One one hand, a entity that can move separately, has a self-contained nutrition cycle with the outside world on the day to day basis, responds separately to stimuli, etc. seems like an organism in and of itself, and our language takes that position. On the other hand, no bee can reproduce without the queen of the hive, the reactions of individual bees can be compared to instictive reactions -- while the higher level thought is directed by the queen through chemical messages not unlike the nervous system to other bees, individual bees are remarkably self-sacrificing if viewed as individual organisms, and there is even specialization in terms of food production.

Back to the point at hand, I think the defensible position to take is that we have evidence that stars are moving rapidly away from each other, that there is evidence that the oldest objects that can be observed are of a given age, the amount of cosmic radiation in the universe is consistent with a particular age of the universe, and the structure of the universe in terms of clumps of matter being close together and clumps of matter being far apart is consistent with what gravity would predict if everything in the universe was once very close together and then rapidly expanded. No one has offered a theory that better explains the observed facts than the Big Bang, and we certainly have evidence of a very old universe confirmed by mutiple lines of evidence.

Did God Do It? Is this part of a bigger scheme? Who knows? Not knowning may provide a basis for being a deist or an agnostic. But, proof of we don't know is not proof of God Did It. Human history of full of things explained by Gods that we now know that God has nothing to do with. Thunder and lightning, rainbows, when it rains, mental illness (attributed to demons in the NT), linguistic diversity, eclipses of the sun and the moon, disease, the evolution of life, and more. Given this track record, God Did It seems an unlikely explanation of those things that science has not yet explained.

Friar Bellows

Go and read this:

<a href="http://www.astro.ucla.edu/~wright/cosmo_01.htm" target="_blank">Ned Wright's Cosmology Tutorial</a>

After that, read the FAQ to make sure your basic understanding isn't awry:

<a href="http://www.astro.ucla.edu/~wright/cosmology_faq.html" target="_blank">Frequently Asked Questions in Cosmology</a>

But I suspect you'll have to read about the philosophy of science before you can argue with a Christian minister/philosopher.

lpetrich

My first thought is that it would be difficult to debate something that one does not have a detailed knowledge of. However, you may want to invite this gentleman to debate some of us Internet Infidels.

As to the Big Bang, I'll try to give you an overview of cosmology. I don't know how much astronomy you are familiar with, so I'll be a bit on the basic side. Here's a powers-of-10 scaling:

AU = Astronomical Unit (Earth's average orbit radius)
pc = parsec (parallax second, about 206265 AU's or 3.26 light-years)
kpc = kiloparsec (10^3 parsecs)
Mpc = megaparsec (10^6 parsecs)

The distances will be assumed to be around one's observation point

1 m (10^0) -- than typical body size
10 m (10^1) -- size of a small building
100 m (10^2) -- size of a city block or a few of them
1 km (10^3) -- size of a neighborhood; height of lower clouds
10 km (10^4) -- size of a medium-sized town; height of upper clouds and where airliners fly
100 km (10^5) -- distance between medium-sized towns; atmosphere gets very thin
1000 km (10^6) -- typical big state or nation size; in outer space above low-earth-orbit satellites
10,000 km (10^7) -- bigger than the Earth
100,000 km (10^8) -- synchronous-orbit satellites are inside
1,000,000 km (10^9) -- the Moon's orbit is inside
10,000,000 km (10^10) -- Near interplanetary space
100,000,000 km or 0.67 AU (10^11) -- Venus and Mars sometimes get this close to the Earth
6.7 AU (10^12) -- the Sun, the inner planets, many asteroids, and Jupiter are all inside
67 AU (10^13) -- the outer planets and the Kuiper Belt of cometlike objects is inside
670 AU (10^14) -- the Oort cloud of cometlike objects is partially inside
6700 AU (10^15) -- same as earlier
67,000 AU or 0.32 pc (10^16) -- same as earlier
3.2 pc (10^17) -- some nearby stars inside
32 pc (10^18) -- more stars
320 pc (10^19) -- even more stars, some nearby star clusters
3.2 kpc (10^20) -- stars are in a thin sheet, with a strip of bright stars and interstellar dust
32 kpc (10^21) -- the sheet and strip are a disk with spiral arms; in the center is a bulge
320 kpc (10^22) -- the Magellanic Clouds, some very nearby galaxies
3.2 Mpc (10^23) -- nearby galaxies like the Andromeda Galaxy
32 Mpc (10^24) -- more nearby galaxies
320 Mpc (10^25) -- lots and lots of galaxies, many in clusters; looking back 1 billion years
3200 Mpc (10^26) -- looking back 10 billion years to when quasars were abundant; they are now mostly burned out

One hits the Big Bang if one goes much beyond that point.

lpetrich

As to the Big Bang itself, that is evident from finding out how fast the galaxies are moving. Many galaxies are in clusters, and they have a random scatter of motions relative to each other. But on the average, the galaxies are moving away from us, with a speed proportional to their distance -- at least if they are not very far on a cosmic scale.

This means that the galaxies must have started from a single point, and that starting is what's known as the Big Bang.

Furthermore, it is evident that galaxies have had a history, because quasars, extremely luminous galaxy centers, had been common at redshifts around 3 (something like 10 billion years ago), but are rare among nearby galaxies. This means that whatever nearby quasars had existed must have burned out by now.

Since the Universe had been more compressed in the past, it must have been hotter -- and if one looks far enough back, it must have been hot enough to ionize its substance. And indeed we find a leftover glow from the Big Bang, released as it grew cool enough to recombine and become much more transparent. However, it has been redshifted into the microwave region of the spectrum and a temperature of 2.7 K (very cold!).

Farther back, it was even hotter -- hot enough to cause nuclear reactions and to form the lightest elements (all the heavier ones were formed in the cores of massive stars).

And if one goes really far back, one gets into Terra Incognita -- quantum gravity.

Tim Thompson

pepperlandgirl: Anyway, can someone give me a fairly simple explanation so I am at least armed with something the next time this discussion starts?

Try <a href="http://casswww.ucsd.edu/public/tutorial/BB.html" target="_blank">The Big Bang</a>, from <a href="http://casswww.ucsd.edu/public/astroed.html#TUTORIAL" target="_blank">Gene Smith's Astronomy Tutorial</a>. Aside from <a href="http://www.astro.ucla.edu/~wright/cosmolog.htm" target="_blank">Ned Wright's Tutorial</a>, which somebody else already mentioned, it's about as good an example of a big bang tutorial that you will find. I also recommend going to the library and/or book store, and looking up <a href="http://www.amazon.com/exec/obidos/ASIN/0465024378/qid=1015549190/sr=1-6/ref=sr_1_6/103-6731694-9558235" target="_blank">The First Three Minutes</a> by <a href="http://www.ph.utexas.edu/~weintech/weinberg.html" target="_blank">Steven Weinberg</a>. Though originally published in 1977, the 1993 reprint has some additional updating remarks by Weinberg. It's still probably the best, all-around, general introduction to basic big bang cosmology.

The basic scenario starts with the apparent observation that the universe is expanding. What we actually observe are "redshifts" of the light from distant galaxies. Be careful of the words here, because "redshift" and "reddening" are not the same thing (a fact not known by all creationists). "Reddening" refers to the removal of the "bluer" colors by some intervening stuff, like dust, so thing look more red than they otherwise would. However, "redshift" refers to a shifting of the galactic absorption spectrum towards the red color direction. The simplist interpretation of that shift is that it is induced by relative velocity away from us. The redshift is definitely correlated with distance, and that implies that the whole array of visible galaxies is expanding, with those most distant apparently moving faster. There are a lot of people who don't like the big bang idea, but try as they may, they have never come up with a better explanation for the systematic redshifts.

If the universe is expanding, one only needs to run the cosmological clock backwards in mundane fashion, to find everything all compacted into the same geometric point, at some time in the past. The sudden (or so we assume) "explosive" expansion of everything that exists, away from that single point, is the nascent event of the "Big Bang" (the name was invented by Fred Hoyle with the intention of being an insult, but it stuck, to his infinite chagrin no doubt).

Most of those who reject big bang cosmology do so on the grounds that it is absurd to assume that all of the universe was once compacted into a true point, and so it cannot be true. They have a point, but miss the mark. The idea is an inevitable consequence of the observation that the universe is expanding (in the absence of any better explanation for redshifts). If the universe is expanding, then there is no escaping the logical consequence that it must have been "smaller" in the past. Physics as we know it does not allow "smaller" to be anything bigger than "microscopic", in this context. Classical general relativity requires "microscopic" to be in fact "infinitesimal" (or "singular", a fact proven by Stephen Hawking for his PhD). But yet to be discovered quantum cosmology may only require "microscopic" to be "almost infinitesimal". In the "infinitesimal" game, the difference between "almost" and "exactly" is really big. So the true nature of the bang event remains a hot topic of theoretical research.

However, the early phases of the post-bang universe, leave clues behind. The big three clues are (1) the <a href="http://www.astro.ubc.ca/people/scott/faq_basic.html" target="_blank">cosmic microwave background radiation</a> (CMBR), (2) the relative abundance of light elements in the universe, and (3) the expanding universe.

The CMBR is required by big bang theory to meet several specifications. It must be strictly thermal, it must not be exactly the same in all directions, and the angular distribution of variations must meet other criteria that are too theoretical to go into here. Suffice to say that it does in fact meet all of those criteria. Other, alternate cosmologies could meet these criteria, but only by coincidence. But the big bang requires these exact criteria. The more such required criteria a theory meets, the more likely it is to be right.

Light element abundances refers to the relative amount of hydrogen, deuterium, helium and lithium, all of which are cooked in the nuclear furnace of the early post-bang universe. Deuterium and lithium are destroyed in stars, and so they are problematical to study, but hydrogen & helium are much easier. The universe is roughly 76% hydrogen and 24% helium (I don't recall the exact numbers, but that's close). That relative fraction is required by big bang cosmology, which has a really hard time creating any other relative abundance.

And, of course, we have already visited the expanding universe, which is tied to the observation & interpretation of galactic redshifts.

So, the big bang is really an entirely empirical idea. It's not something from a theoretician's dream. Rather, it's the natural (dare I say "necessary") consequence of an expanding universe. Once we get used to the idea that the universe is expanding, some kind of bang can't be intellectually far away.

Of course, the question always arises, How did it get that way in the first place? And the anwswer has to be Who knows?. Creationists like that answer, which usually prompts the response that if you can't prove it was not God, then it must have been God. Modern mathematical shenanigans, like string theory or quantum gravity might be able to explain what the pre big bang universe looked like, but any practical results along those lines remain a few years/decades away.

Is that simple enough?

[ March 07, 2002: Message edited by: Tim Thompson ]</p>

Friar Bellows

I understand that you're trying to keep things simple, but sometimes I wonder if, in doing that, we don't confuse the newbies even more. There's been a trend in pedagogy in recent years of attributing emotions to inanimate objects. For example, "air hates to be crowded, and when compressed it will try to escape to an area of lower pressure", and "rain water runs off the mountains toward the ocean; it tries to run down the steepest slope it can find". This so-called "pathetic fallacy" is an example of what I mean when I say that we might confuse the newbies even more by using simple analogies and trying to simplify the explanations.

So, in your case, I think that attributing the cause of the cosmological redshift to "relative velocity" might be misleading for the newbies, even though knowledgable people know what you mean. As I'm sure you're aware, cosmological redshift has nothing to do with the Doppler effect. Cosmological redshift is dependent on the total amount of expansion of spacetime between the moment of emission and the moment of reception. The Doppler effect, is dependent on the relative velocity of the emitter and the reciever at the instants of emission and reception. The former depends on everything that happens in between, the latter depends only on what is happening at the beginning and the end.

The reason that this is important is that newbies need to get rid of the idea that the Big Bang is an explosion in space. It's not about galaxies travelling at high velocity through space. It's about space itself expanding, a bit like stretching a rubber sheet. OK, now I've introduced an analogy, which is yet another way we can simplify things too much to newbies.