Recent comments in /f/askscience

Obvious_Swimming3227 t1_j27skmu wrote

Reply to Before Newton, how did people explain falling apples? by maugustus

There was for a long time the Aristotelian nonsense about objects seeking out their natural resting place, but, by the time of Newton, Galileo had dealt a pretty lethal blow to that. Probably the fairest answer is that we were at the beginning then of a modern scientific understanding of the world, and that a coherent model of what caused things to fall to the ground as we understand it now probably didn't really exist then. I could be wrong-- particularly with respect to the advances that were taking place outside of Europe-- but it seems like science before this period was largely about illustrating a beautiful, rational order ordained by God, rather than finding rigorous models that could explain natural phenomenon: Science was still a branch of philosophy. People like Galileo, Copernicus, Newton, etc, aren't giants simply because they corrected long-running misperceptions about things, but because they introduced a fundamental paradigm shift into how we think about the world and ask questions about it.

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Implausibilibuddy t1_j27r5tq wrote

Reply to comment by Aseyhe in How fast does the Milky Way spin? How far does Earth move through space in a year? by Sabre-Tooth-Monkey

How does that work? I don't doubt it but it runs counter to my experience of kerbal space program orbital simulation software wherein an increase in orbital diameter requires an increase in velocity. Conversely, to decrease your altitude you must decrease your orbital velocity. 10 objects orbiting at the same velocity around a planet, in a perfectly circular orbit, will all be the exact same distance from the centre of the planet.

Actually, I've just looked up the moon's orbital velocity at 1km/s and low earth orbit as 7km/s so that's the complete opposite of what the simulation implies, which definitely requires prograde burns to increase apoapsis. I may need a layman's explanation for all this craziness.

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randomnickname99 t1_j27r5e7 wrote

Reply to comment by Narwhal_Assassin in How fast does the Milky Way spin? How far does Earth move through space in a year? by Sabre-Tooth-Monkey

Let's say I have two guns that shoot bullets at the speed of light. I simultaneously shoot one to my right and one to my left. If I follow correctly, I can look left or right and see a bullet moving away at the speed of light. But if the bullets looked at each other they would only see themselves moving apart at the speed of light.

Here's the part I never understood though. Let's say I was standing directly between two walls that were 600,000 km apart. When I shoot the guns I should be able to see each bullet travel for one second before hitting the wall. But from the bullet's perspective that's impossible, because they would have had to travel apart at 2c to do so. How is that reconciled?

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IhoujinDesu t1_j27qqw7 wrote

Reply to comment by shadow29warrior in How fast does the Milky Way spin? How far does Earth move through space in a year? by Sabre-Tooth-Monkey

Relative to the CMB. The cosmic background radiation as a distant and very uniform reference frame can tell us about our motion through space due to doppler shift. It will vary throughout the year as we swing around in our orbit. And there is a consistant bias due to the sun's orbit around the milky way and the overall motion of the galaxy.

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enterpriseF-love t1_j27njv7 wrote

Reply to comment by gerd50501 in Is the BF.7 mutation of Omicron less severe than variants? by Active_Bedroom_5495

Yep the bivalent (BA.5) booster will fare better against BF.7. The US has inhaled vaccines under development but those haven't gotten that far partly due to funding, research, or political reasons.

BF.7 is a bit more immune evasive + transmissible compared to BA.5 and shows reduced sensitivity to monoclonal antibodies likely due to an amino acid change at R346T.

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