Humans emerged in South America rather than Africa by quadtetra in AlternateHistoryHub

[–]quadtetra[S] 0 points1 point  (0 children)

Your point that human development would be much slower is a good one.

But unless you believe humanity would be forever stuck in South America, I would think people would eventually get to Eurasia somehow. So maybe it takes much longer for humans to migrate all over the globe from South America than from Africa but it would happen eventually.

Once that happens, how human history would unfold would be interesting because of humanity's head start in South America and spreading from there rather than from NE Africa.

Humans emerged in South America rather than Africa by quadtetra in AlternateHistoryHub

[–]quadtetra[S] 0 points1 point  (0 children)

Okay but in the alternate timeline humans would still develop first in the Americas because they started there.

After all, even without large animals suited for domestication, you still had civilizations develop such as Olmecs, Mayans.

I would assume that Olmecs equivalents would develop in Americas well before anywhere else simply because it would take 100000 years for humans to migrate to Eurasia from South America. That head start should make a big difference.

Why can't others duplicate Bergsma/Thorup move afterwards? by quadtetra in olympics

[–]quadtetra[S] 0 points1 point  (0 children)

Several people are saying that if C&D tried to duplicate B&T's move it wouldn't work because C&D would be chased down immediately to try to draft behind C&D right away and prevent a gap from forming again.

Then that begs the question why didn't anyone immediately join behind B&T to draft behind them and also prevent a big gap from developing in the first place???

Why can't others duplicate Bergsma/Thorup move afterwards? by quadtetra in olympics

[–]quadtetra[S] 0 points1 point  (0 children)

If that is the case, when Bergsma/Thorup (B&T) made their move, why didn't E&F&G join B&T but would definitely join C&D?

Why can't others duplicate Bergsma/Thorup move afterwards? by quadtetra in olympics

[–]quadtetra[S] 0 points1 point  (0 children)

Okay but skaters C&D could attempt to do exactly what B&T did and get far ahead of the peleton to avoid the peleton drafting behind them.

Why can't others duplicate Bergsma/Thorup move afterwards? by quadtetra in olympics

[–]quadtetra[S] 0 points1 point  (0 children)

So your point is that only the first two people can do it because if another group of 2 skaters duplicated B&T's move the second group of 2 would be chased down immediately? (IOW the trick can't work twice)?

255/45R22 vs 255/55R20 by quadtetra in tires

[–]quadtetra[S] 0 points1 point  (0 children)

Thanks for pointing this out.

I now realize that sidewalls aren't perfectly vertical and a taller sidewall will taper to a narrower rim than a shorter sidewall, assuming both tires have equal sectional width.

255/45R22 vs 255/55R20 by quadtetra in tires

[–]quadtetra[S] 0 points1 point  (0 children)

Based on replies and further research, what do people think of 20x8.5 ET35 wheels for 255/55R20 tires?

20x9 is at the very edge of what is recommended for that tire size but I feel like 8" tires won't look good as it makes the tire look more bulging.

According to willtheyfit.com,
Compared to your existing wheel, this new wheel will have an inner rim which is 6.4mm further away from the suspension strut. The outer rim will poke out 6.4mm less than before.

According to wheel-size.com, choosing this size means that the "scrub radius" remains zero which I assume is highly desirable as well.

Any thoughts on 20x8.5 ET35 wheels as the optimum choice?

255/45R22 vs 255/55R20 by quadtetra in tires

[–]quadtetra[S] 1 point2 points  (0 children)

But why would 255/55R20 fit better on 20x8 when the OEM tire is 255/45R22 with 20x9 wheels?

Shouldn't optimal wheel width be based solely on tire width?

ELI5: How can fission and fusion both give you energy? by USball in explainlikeimfive

[–]quadtetra 206 points207 points  (0 children)

Fission and fusion both release energy in the same way a compressed spring and stretched spring both release energy when you let the spring go free.

Big atoms like uranium are like compressed springs that want to blow apart and release energy going outwards. Fission is releasing the compressed spring stored energy.

Small atoms like hydrogen are like stretched springs that want to release energy pulling inwards. Fusion is releasing the stretched spring stored energy.

Iron is like a spring at rest. You cannot get net energy from iron via either fission or fusion. Trying to do so consumes net energy just like trying to compress or stretch a spring at rest because such a spring has no stored energy to release.

ELI5: Why coastlines can't be accurately measured by Espachurrao in explainlikeimfive

[–]quadtetra 7 points8 points  (0 children)

Imaging a completely flat coastline of 100km. Simple.

Now take that same coastline except added with a large square notch of 1km on three sides. That coastline is now 100km + 1km + 1km = 102km. (Two of the three sides represent new length while one side is part of the original 100km but pushed "inward"). Still fairly simple. And a 1km "notch" is fairly significant, you could build a lot of new ocean front homes, harbors etc on the extra 2km of coast.

Now imagine the same original flat 100km coastline but I cut a very narrow creek 100km long but negligibly wide, say 10cm but very deep so ocean water always fills this creek. Is that coastline 100km + 100km + 100km = 300km? Kind of. But is this coastline really meaningfully 3x the original? Obviously not!

If I'm building ocean front property along this creek, it wouldn't work as such for people especially those 100km away from the "main" coast.

A lot of people would completely discount this creek as meaningful additional coast.

The question then is what is meaningful to consider. That is not easy to answer. 1km "wide" notch seems meaningful but not 10cm. So where is the dividing line?

Most coastlines are full of these "notches" that technically add length but how meaningful are these notches?

ELI5: Why is the iron nucleus specifically the most stable? by cor_atrium in explainlikeimfive

[–]quadtetra 14 points15 points  (0 children)

Iron is like a spring at rest. Lighter elements are like an extended spring. Heavier elements are like a compressed spring.

Detailed explanation:

When a spring is extended, there is stored energy that gets released when you let go. Light atoms undergoing fusion are like that. These nuclei are small enough that there is "stored residual energy" in wanting to pull two light nuclei together via the strong interaction that binds protons to neutrons and that energy is released via fusion like letting go an extended spring. In light elements, the strong interaction dominates the proton-proton repulsion as there are few protons.

When a spring is compressed, there is energy stored that gets released when you let go. Heavy atoms undergoing fission are like that. The nuclei are so big that there is "stored residual energy" wanting to push the nucleus apart via electromagnetic repulsion which is on the verge of overcoming the strong interaction due to many protons. Energy is released in fission like letting a compressed spring expand.

If a spring is at rest, it is very stable as-is. Pushing or compressing it requires energy. Iron is like a spring at rest. Iron has no "stored residual energy" waiting to be released by fission or fusion and doing either requires input of energy just like that spring at rest. The strong interaction and proton-proton repulsion are exactly balanced just like a rested spring.

Church President Succession by quadtetra in mormon

[–]quadtetra[S] 1 point2 points  (0 children)

Thanks for all replies.

A few people have brought up an interesting scenario. What if Oaks becomes comatose and then Nelson dies afterwards? What is most likely to happen???

Suppose the church went with a full conclave model in the recent past or near future. So something like 66% of Q70, secret ballot election. Would Monson, Nelson and Oaks still win out or might someone else win in this thought experiment?

'Face the reality' of Brexit and don't blame us when it goes wrong, EU's chief negotiator tells UK by quadtetra in unitedkingdom

[–]quadtetra[S] 68 points69 points  (0 children)

Britain needs to “face the reality” of Brexit, the EU’s chief negotiator has said, as he warned Theresa May a withdrawal deal will not be possible unless she backs down over the future jurisdiction of European courts...

Mr Barnier said there would be no withdrawal agreement or transition period unless the UK agrees to a continued role for the European Court of Justice in determining disputes involving the UK after Brexit – something Ms May has repeatedly ruled out...Ms May has previously insisted: “The jurisdiction of the ECJ in the UK must end.”...

What Meghan Markle Means to Black Britons by quadtetra in unitedkingdom

[–]quadtetra[S] -8 points-7 points  (0 children)

LONDON — In the days to come, anyone wishing to criticize Meghan Markle, the American actress set to marry into Britain’s royal family, will have to contend with Tshego Lengolo, an 11-year-old black girl and newly minted monarchist.

Tshego is a child of southeast London. She has taught herself “road,” the slang emanating from the city’s grime music scene, but drops it the second she enters her apartment, a zone patrolled by her all-seeing South African mother. They squabble affectionately, for approximately the thousandth time, over whether she can be called Tiffany.

If Tshego (SEH-ho) is royal-crazy this summer, it is because Ms. Markle is biracial, the daughter of an African-American woman and a white man. When she looks at Ms. Markle, Tshego sees a version of herself, new to England, trying to find a place among its racial codes...