Wikipedia:Reference desk/Archives/Science/2025 August 2

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August 2

Sun's power per cubic meter

The sun produces a lot of power. But the sun is very large. If we calculate power per cubic meter as an average for the whole sun we get an oddly small value. But most of the fusion occurs in a relatively small volume of the sun, so can we estimate how much power is produced by a cubic meter near the center of the sun? RJFJR (talk) 02:54, 2 August 2025 (UTC)[reply]

What kind of power? Electrical power? ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:13, 2 August 2025 (UTC)[reply]

Almost all energy is produced in the solar core, which takes up about 3% of the Sun's volume. The more you confine the size of the ball around the solar centre, the higher the power density. According to the section Solar core § Energy conversion, the fusion power density at the centre is estimated by models to be about 276.5 W/m³.  ​‑‑Lambiam 06:06, 2 August 2025 (UTC)[reply]

Species with clones

Are there animal species where it's for common for individuals to share the complete DNA sequence? For example, there are over 300 billion whiteleg shrimp farmed each year, and the female spawns over 100,000 eggs at a time. Unless there's a large number of unique genes for that species, I would imagine there must be some clones? Probably more for microorganisms. 184.96.140.185 (talk) 18:57, 2 August 2025 (UTC)[reply]

See Parthenogenesis.-Gadfium (talk) 20:06, 2 August 2025 (UTC)[reply]

What about for non-asexual species? 184.96.140.185 (talk) 20:55, 3 August 2025 (UTC)[reply]

Assuming the members of both sexes are diploid – which is not the case for all animal species – the number of possible combinations for the gametes resulting from meiosis equals 2^C/2, in which C stands for he number of chromosomes of the species. Fertilisation, even wthout genetic recombination of chromosomes, gives 2^C possible combinations.

For Homo sapiens, C = 46, and 2⁴⁶ is humungous, but there are animal species with far fewer chromosomes; see List of organisms by chromosome count. It appears likely that among some of these there are genetically identical individuals.  ​‑‑Lambiam 08:24, 4 August 2025 (UTC)[reply]

Aren't there millions of genes for each chromosome though? 184.96.140.185 (talk) 15:14, 4 August 2025 (UTC)[reply]

May be thousands of genes per chromosome, but don't forget about chromosomal crossover which means that the offspring won't inherit whole chromosomes from their grandparents. Graeme Bartlett (talk) 22:56, 4 August 2025 (UTC)[reply]

It's not a case of the type of 'incidental' clone you seem to be searching for, OP, but you might nevertheless be interested in the reproductive life cycle of aphid species which generally alternate between sexual/recombinant and parthenogenetic/clonal reproduction. SnowRise ^{let's rap} 07:30, 6 August 2025 (UTC)[reply]