The human population is at 7.7 billion. Has any other mammal ever reached that population level? | AskScience Blog

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Monday, March 11, 2019

The human population is at 7.7 billion. Has any other mammal ever reached that population level?

The human population is at 7.7 billion. Has any other mammal ever reached that population level?


The human population is at 7.7 billion. Has any other mammal ever reached that population level?

Posted: 10 Mar 2019 01:28 PM PDT

How does your finger "remember" its finger print?

Posted: 11 Mar 2019 01:36 AM PDT

So we all know that a person's fingerprint cannot change naturally. So how does it still produce the same print after the skin is torn? Would the same thing happen if it's burnt?

submitted by /u/Righart
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How do Gyroscopes in electronic devices work?

Posted: 10 Mar 2019 08:33 PM PDT

I've been trying to wrap my mind around how these things work, after playing on a switch for the first time and seeing that the gyro not only detects rotations and flips but also when you turn. So if I sit in a swivel chair and hold the switch in front of me it will detect the full spin of the chair.

I can't wrap my head around how it does this. My first theory was some kind of gyro with a compass to show which way you are facing, but even fast movements are precise, where a compass would wobble a bit.

How exactly are these things detecting full range of motion?

submitted by /u/DocumentaryAndChill
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Why doesn't a pregnant womans immmune system attack the baby?

Posted: 10 Mar 2019 10:10 PM PDT

Why doesn't a pregnant womans immune system attack the baby? Because it is kind of a foreign object in the body since it's different dna?

submitted by /u/wabahoo_on_you
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Why is memory sometimes lost after trauma?

Posted: 11 Mar 2019 01:33 AM PDT

Why is it that in most cases you hear of, it's usually short term or long term memory that is affected or lost after experiencing some kind of head trauma? Why is remembering how to talk or involuntary function rarely affected?

submitted by /u/robbie8six
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Why are Neanderthals classified as a different species from Homo Sapiens?

Posted: 10 Mar 2019 09:53 PM PDT

If they can mate and form viable genetic offspring, what makes them a separate species? Please feel free to apply this same line of logic to all the other separate species that can mate and form viable offspring.

submitted by /u/SketchyFella_
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Are there any known computational systems stronger than a Turing Machine, without the use of oracles (i.e. possible to build in the real world)? If not, do we know definitively whether such a thing is possible or impossible?

Posted: 11 Mar 2019 08:27 AM PDT

For example, a machine that can solve NP-hard problems in P time.

submitted by /u/heyheyhey27
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How are new alloys discovered?

Posted: 11 Mar 2019 01:40 AM PDT

Some alloys have very a long list of very specific amounts of constituents.

For example, Eglin steel is defined as having:
- Iron (84.463–90%)
- Carbon (0.16–0.35%)
- Manganese (0.85%)
- Silicon (max. 1.25%)
- Chromium (max. 1.50–3.25%)
- Molybdenum (max. 0.55%)
- Nickel (5.00%)
- Tungsten (0.70–3.25%)
- Vanadium (0.05–0.3%)
- Copper (0.50%)
- Phosphorus (impurity, max. 0.015%)
- Sulfur (impurity, max. 0.012%)
- Calcium (max. 0.02%)
- Nitrogen (impurity, max. 0.14%)
- Aluminium (max. 0.05%)

How do you end up with these exact quantities of elements? Is it by trial-and-error? Or is there some theoretical basis for mixing the ingredients? Can you predict the material's properties from based on the composition?

submitted by /u/IndependentGuy
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Why is the sky not violet?

Posted: 11 Mar 2019 02:39 AM PDT

Violet has the least wavelength so according to Rayleigh's Law, it would be scattered the most and should be the colour we see the sky as. Why is this not the case?

submitted by /u/notobscurereference
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Is a jellyfish able to sting itself, and if it does what happens?

Posted: 10 Mar 2019 07:23 PM PDT

Rutherford scattering and positively charged nucleus?

Posted: 11 Mar 2019 04:07 AM PDT

Hi all, how did Rutherford arrive at the conclusion that the nucleus of the gold foil was positively charged.

The Rutherford scattering cross section formula is symmetric in charge. Which means both positively and negative charged nucleus could have gave him the same experimental results.

For those skeptical, his 1911 paper only concludes that the small dense nucleus has either a very large positive charge or very large negative charge.

TLDR What evidence helped Rutherford conclude that the nucleus was positively charged?

submitted by /u/StepHawking
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Has any virus or bacteria in humans ever mutated within us to then become a serious illness elsewhere in the animal kingdom?

Posted: 10 Mar 2019 04:50 PM PDT

Why is Hagfish in the subphylum Vertebrata despite having no vertebra/arculia?

Posted: 11 Mar 2019 12:41 AM PDT

During the Fukushima nuclear plant meltdown water was split into hydrogen and oxygen which subsequently exploded. How does this work and how did a supply of gas accumulate without simply burning immediately?

Posted: 10 Mar 2019 06:01 PM PDT

Why does a pot of water or tea pot make the most noise right before the water reaches boiling?

Posted: 10 Mar 2019 04:20 PM PDT

Then it seems to get quieter once it reaches a rolling boil.

submitted by /u/senrnariz
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Do Chloramines in tap water negatively affect human gut microbiome?

Posted: 10 Mar 2019 07:31 PM PDT

Basically the title. I've heard different things about how important the human gut microbiome is to health, and since chlorine and chloramines are typically used to sterilize tap water would it do the same to the human microbiome?

submitted by /u/ramdangeriii
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Does marking a "deep end" of a pool have any effect on rates of drowning or injury?

Posted: 10 Mar 2019 08:26 PM PDT

Most pools I've been to that are deeper than 5 feet delineate between a "shallow end" and the "deep end." The shallow end is normally marked as "no diving," though exceptions are made for swim meets. Is there any evidence that separating the pool into these two sections makes the pool safer to swim in?

submitted by /u/potator
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How did angular momentum come from a singularity?

Posted: 10 Mar 2019 10:20 PM PDT

We know that the early universe was not "homogeneous" because of the cosmic background radiation, but the singularity would have been initially homogeneous by definition. Wouldn't this singularity have to had expanded unevenly for the occurrence of varied forces that cause transnational and rotational motion?

submitted by /u/SleepyHobo
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Does Magnesium and water result in no reaction?

Posted: 10 Mar 2019 08:27 PM PDT

Mg + H2O = NR?

-OR-

Mg + 2 H2O = H2 + Mg(OH)2 ?

I see some sites showing it does result in magnesium hydroxide and hydrogen. But it isn't on the list of metals that react with water. Can anyone clarify this?

submitted by /u/ihugtrees91
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Spacetime isn't like a trapeze net at all is it?

Posted: 10 Mar 2019 09:00 PM PDT

I understand the common descriptives of comparing spacetime to a trapeze net. While it did help at first to wrap my brain around it all, I cannot help but feel like it skips some dimension(s). Is there a better of an exanple anyone knows of that is a bit closer to what spacetime would appear as? 🖖

submitted by /u/Dumble-
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Is it true that you can theoretically make glass out of anything if you cool it fast enough?

Posted: 10 Mar 2019 08:06 PM PDT

I took a class in materials science and the professor said this on multiple occasions, and I believe that I understand it, but I'd like to verify it before it becomes my go-to fun fact.

submitted by /u/UbiquitousSham
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How would orbital bombardment affect the weather?

Posted: 10 Mar 2019 07:43 PM PDT

Trying to write a bit of SF and I'm curious about the meteorological effects of orbitally bombarding an earthlike planet. This comment from AskHistorians about the environmental impacts of WWII is about all the information I have. However, it's concerned with strategic bombing, not orbital bombardment, and it is somewhat vague on the practical consequences of the ionosphere diminishing.

Specifically, I am concerned with bombardment that is somewhat precise (Aimed for selected targets, not indiscriminate glassing) and sustained (More than a week long but less than a month per target area). I have two scenarios in mind: A) The attackers are using a mix of kinetics and conventional explosives for the bombardment B) The attackers are using projectiles that give off very high amounts heat energy, especially upon impact.

Thank you for your help!

submitted by /u/Commissar_Cactus
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How are primers made for PCR chosen?

Posted: 10 Mar 2019 07:02 PM PDT

After DNA has been extracted, how does one know what sequence of nucleotides is complementary to the DNA? PCR is used to increase the amount of a specific part of the DNA so that the DNA can be sequenced, right? How do we know the sequence of that DNA well enough before PCR in order to make a primer for that segment of DNA?

submitted by /u/PebbleSea
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Did humans develop complex vocal chords as an accidental byproduct of evolving to have longer necks or did ancient humans slowly develop them by making enough sounds that more complex vocal chords were forced to be developed?

Posted: 10 Mar 2019 01:36 PM PDT

Did humans just get really lucky to be social animals that accidentally developed complex vocal chords?

submitted by /u/Bathysmal10
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