Claim:
Every event has a cause. The universe itself had a beginning, so it must have had a First Cause, which must have been a creator God.
Response:
1. The assumption that every event has a cause, although common in our experience, is not necessarily universal. The apparent lack of cause for some events, such as radioactive decay, suggests that there might be exceptions. There are also hypotheses such as alternate dimensions of time or an eternally oscillating universe which allow a universe without a first cause.
2. By definition, a cause comes before an event. If time began with the universe, "before" doesn't even apply to it, and it is logically impossible that the universe be caused.
3. This claim raises the question of what caused God. If, as some claim, God doesn't need a cause, then by the same reasoning, neither does the universe.
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Claim:
Cosmologists can't explain where space, time, energy, and the laws of physics came from.
Response:
1. Some questions are harder to answer than others. But although we don't have a full understanding of the origin of the universe, we are not completely in the dark. We know, for example, that space comes from the expansion of the universe. The total energy of the universe may be zero. Cosmologists have hypotheses for the other questions that are consistent with observations [Hawking 2001]. For example, it is possible that there is more than one dimension of time, the other dimension being unbounded, so there is no overall origin of time. Another possibility is that the universe is in an eternal cycle without beginning or end. Each big bang might end in a big crunch to start a new cycle [Steinhardt and Turok 2002] or, at long intervals, our universe collides with a mirror universe, creating the universe anew [Seife 2002].
One should keep in mind that our experiences in everyday life are poor preparation for the extreme and bizarre conditions one encounters in cosmology. The stuff cosmologists deal with is very hard to understand. To reject it because of that, though, would be to retreat into the argument from incredulity.
2. Creationists can't explain origins at all. Saying "God did it" is not an explanation, because it is not tied to any objective evidence. It doesn't rule out any possibility, or even any impossibility. It does not address questions of "how?" and "why?", and it raises questions such as "which God?" and "how did God originate?" In the explaining game, cosmologists are far out in front.
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Claim:
The cosmos is fine-tuned to permit human life. If any of several fundamental constants were only slightly different, life would be impossible. (This claim is also known as the weak anthropic principle.)
Response:
1. The claim assumes life in its present form is a given; it applies not to life, but only to life as we know it. The same outcome results if life is fine-tuned to the cosmos.
We don't know what fundamental conditions would rule out any possibility of any life. For all we know, there might be intelligent beings in another universe arguing that if fundamental constants were only slightly different, then the absence of free quarks and the extreme weakness of gravity would make life impossible.
Indeed, many examples of fine-tuning are evidence that life is fine-tuned to the cosmos, not vice versa. This is exactly what evolution proposes.
2. If the universe is fine-tuned for life, why is life such an extremely rare part of it?
3. Many fine-tuning claims are based on numbers being the "same order of magnitude," but this phrase gets stretched beyond its original meaning to buttress design arguments; sometimes numbers more than 1000-fold different are called the same order of magnitude [Klee 2002].
How fine is "fine" anyway? That question can only be answered by a human judgment call, which reduces or removes objective value from the anthropic principle argument.
4. The fine-tuning claim is weakened by the fact that some physical constants are dependent on others, so the anthropic principle may rest on only a very few initial conditions that are really fundamental [Kane et al. 2000]. It is further weakened by the fact that different initial conditions sometimes lead to essentially the same outcomes, as with the initial mass of stars and their formation of heavy metals [Nakamura et al. 1997], or that the tuning may not be very fine, as with the resonance window for helium fusion within the sun [Livio et al. 1999].
5. If part of the universe were not suitable for life, we wouldn't be here to think about it. There is nothing to rule out the possibility of multiple universes, most of which would be unsuitable for life. We happen to find ourselves in one where life is conveniently possible because we can't very well be anywhere else.
6. The anthropic principle is an argument against an omnipotent creator. If God can do anything, He could create life in a universe whose conditions do not allow for it.
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Claim:
The first law of thermodynamics says matter/energy cannot come from nothing. Therefore, the universe itself could not have formed naturally.
Response:
Formation of the universe from nothing need not violate conservation of energy. The gravitational potential energy of a gravitational field is a negative energy. When all the gravitational potential energy is added to all the other energy in the universe, it might sum to zero [Tryon 1973; Guth 1997, 9-12,271-276].
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