Recent comments in /f/askscience

JMYDoc t1_jc8xzyg wrote

Reply to Rain vs snow accumulation volume? by krenzar18

Yes. The amount of water in an inch of rain generates up to six inches of snow. The amount depends on a variety of factors which affects the snowflake size and shape and thus “compactness.” The light fluffy snow has the most accumulation.

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nowayjose081 t1_jc8qcfn wrote

Reply to comment by Tank_AT in Does space expansion occur uniformly in all directions and dimensions? by Tank_AT

I might be wrong but you can think of it like this: Between us and andromeda there is 'x' amount of dark energy repulsion. Between andromeda and the next galaxy beyond that there is also 'x' amount of dark energy repulsion. And so on. So between us and some galaxy thats 100 times farther away than andromeda is, there will be 100x amounts of dark energy repulsion.

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saunders77 t1_jc8lb2t wrote

Reply to comment by Aseyhe in Does space expansion occur uniformly in all directions and dimensions? by Tank_AT

Is this askscience FAQ answer about "what is the universe expanding into" incorrect? It's saying that the distance between two "otherwise stationary" points will continue to increase. And that our "cosmic ruler" grows over time. To a non-cosmologist like me that sounds like the expert is saying space itself is expanding

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Aseyhe t1_jc87l2x wrote

Reply to comment by cygx in Does space expansion occur uniformly in all directions and dimensions? by Tank_AT

Odd, I'm not sure why they cite that there. But the error made in the Cooperstock et al. article is pretty elementary, in any event. By starting with the FLRW metric for an Einstein-de Sitter universe, they assume from the outset that matter is homogeneously distributed everywhere at the critical density. The force that they claim arises from the expansion of the universe is really just the gravitational influence of this matter.

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cygx t1_jc85w7p wrote

Reply to comment by Aseyhe in Does space expansion occur uniformly in all directions and dimensions? by Tank_AT

> The tendency to expand due to the stretching of space is nonexistent, not merely negligible.

Note that this claim is at odds with one of the papers that is cited in support (ref. 19 specifically). The final sentence of arXiv:astro-ph/9803097 reads:

> As a conclusion, it is reasonable to assume that the expansion of the universe affects all scales, but the magnitude of the effect is essentially negligible for local systems, even at the scale of galactic clusters.

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Dunbaratu t1_jc7se9d wrote

Reply to Rain vs snow accumulation volume? by krenzar18

Imagine someone who's really bad at playing Tetris. They don't even try to make the blocks fit together well and they make lots of big empty holes in their pile of blocks as the blocks get stuck on each other in the least compact way possible. That makes their pile get high very quickly.

That's what a pile of snow is like. Raindrops are excellent at playing Tetris because liquids will change shape as needed to fill the lowest possible level of the container. Snowflakes on the other hand won't. Their very spread-out shapes, fully of spiky bits at the ends, cannot tessellate.

Snow depth is made mostly of the air gaps in between the flakes that get hung up on each other's spikes.

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lt_dan_zsu t1_jc7sdfw wrote

Reply to CRISPR vs AAV - how do they differ? by HueX1

Multiple ways of gene editing have existed for a while. CRISPR is way more scalable. Other forms of genome editing are either more expensive to target a gene of interest. Other technologies are imprecise. We've been able to insert a gene into a genomes for decades, but it also just randomly inserts it all over the genome.

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