Score
Title
378
AskScience Panel of Scientists XVII
78237
Help us fight for net neutrality!
11142
From my kid: Can you put a marshmallow on a stick out into space and roast it with the sun?
16
What would our world look like if the collision which ejected the material from which formed the Moon had not occurred? Would there be liquid water? What kind of atmosphere if any? Active geological processes? Life?
4
[physics] When I turn off my oven but leave the door closed how does the temperature cool?
3
How accurate is the usual picture of the atomic nucleus of a ball/mass of protons and neutrons? What's really happening in the centre of atoms?
42
On my bike: is it more efficient to pedal fast in a low gear or slower in a high gear?
3
How would the government broadcast an emergency message in today's world where a majority of people watch tv through a streaming service?
1
If the Earth is closer to the sun for a part of the year, why isn't that summer MUCH hotter?
1
How do you define the number of conduction electrons?
10
What makes it "impossible" as of now to detect the hypothetical Graviton particle?
9
How are Muscle Knots / Trigger Points Created at the Cellular Level?
2
Can Dark Matter be explained by scale Invariance of empty space?
17
Is deep-earth nuclear fission heating the Earth's interior?
4
How in the world could a particle have a 1/2 spin value?
3371
Hein et al (2017) have explored scenarios for sending a spacecraft to the recently confirmed interstellar asteroid "Oumuamua". What payloads and capabilities would we wish to prioritize on the exploration of this strange and peculiar object?
11
How are doctors able to determine genetic abnormality in a fetus, by testing the mother’s blood?
11
Are all prime numbers smaller than the biggest prime number discovered?
10
What exactly is the Van Allen radiation belt?
6
Why children with adenoditis fall behind in their neurophychiatric development and do they recover in that aspect after the inflammation is gone?
12
Can blue light cause cancer? What about UVA? Where is the threshold?
4
When there is a momentum transfer between two charged particles (via a virtual particle) is that transfer instantaneous?
10
Do cephalopods control their camouflage consciously, if yes how exactly can an animals thought's change it's cells?
15
How does restricting Internet work?
11
Why can't powerbanks charge while being charged?
9
Is it a coincidence that the moons rotation around its axis matches the duration for its revolution around the earth? Or is there some scientific explanation on how these aligned in such a fashion?
7
Ask Anything Wednesday - Engineering, Mathematics, Computer Science
2
Are there any advantages to Removing Net Neutrality that the consumer can enjoy and not ISPs?
4
How does your body heal cuts?
6
How do they know 'Oumuamua is elongated vs of assymetric albedo? (Bonus Question: Is the assumed rotation stable?)
1
What changes when you break the sound barrier?
10
How, or why, do refraction and dispersion occur?
2
Are electrostatic interactions photon-mediated?
2
How does Lebesgue integral put Riemann integral and discrete sums in the same theorical mold ?
25
Why are radio waves and microwaves more damaging to the human body than light waves?
14
In my Psychology textbook it says that cortisol (a result of stress) reduces telomerase activity, therefore speeding up the aging process, however, I know that exercise also releases cortisol, yet is known to combat aging - how?
2
I measured an imaginary component of Earth's magnetic field?
3
Why does water behave like a mirror?
6
Why don't electrons in a superconductor radiate away their energy?
1
Why does the index of refraction of water change with temperature?
14
Why do planets orbit in planes?
15 Kenley Furthermore, it's conceivable that there were multiple origins of life early on, but the others didn't "make it." Perhaps, for whatever reason, they were less efficient at metabolism or reproduction than life-as-we-know-it, so they weren't able to get a foothold.
12 t_mo 'Possible' is a tricky word in origins biology. For Archae and Bacteria to have *no ancestor in common* would imply a profound level of convergence, a frequentist statistical probability approaching zero. At a certain point in development we have to start asking 'what does an ancestor actually look like', and we have to enter into a discussion of abiogenesis or some other theoretical origin point. We can't pinpoint specifics in the pre-cellular ancestors, and what that would actually look like depends on which perspective you take on likely biological origins. However, whatever we presume for the sake of discussion to be the pre-cellular ancestor of bacteria/archae, we know that it has a very limited number of forms and features. If those forms and features share so much in common (bound by membrane, pre-RNA features of replication, etc) we have to reconsider what the statement of 'two distinct ancestors' would look like even from a theoretical perspective, *could* they be sufficiently distinct while still sharing sufficient features to produce unicellular life as similar in form and function as archae/bacteria, or are we really just looking at two slightly different versions of the same replicating system? As with a lot of questions in origins biology, the discussion is mostly philosophical and not very practical.
5 Rather_Dashing All current life on earth came from a common ancestor. We know this because, among many other lines of evidence, we all have the same dna code (with some minor variation). For example the DNA codon 'TCT' codes for a Serine base. There are 64 different codons and they consistently code for the same amino acid bases across the kingdoms. The odds that two separate origins of life would come up with the same code is astronomically low. However if is possible, even likely, that life arose multiple times, but the other lines died out leaving all the life known today descending from a single ancestor.
2 rocketsocks Likely, in fact. And some of the earliest forms of life may have intermingled because they were so similar (if they weren't much more than just self-replicating RNA polymers, for example). However, at some point one form of life became advanced enough to outcompete all the others by a significant margin, and that became the "last universal common ancestor" (or LUCA) for all current life on Earth. It's possible that abiogenesis type events continue to occur on Earth today but aren't able to get a foothold on a planet with abundant life already. As far as we can tell all life on Earth has a common ancestor, however. We can be pretty certain of this due to the similarities in the core DNA -> RNA -> protein genetic coding pipeline. There is great similarity in the fundamental molecular machinery of all life. They share the same 3-nucleotide codon length, the translation table between codons -> amino acids is remarkably similar across species, the ribosomes, t-rnas, etc. which facilitate translation of RNA to amino acid sequences is also remarkably similar. There are far too many similarities in those core mechanisms to be due to either chance or convergent evolution, which points to a common evolutionary lineage between all life on Earth.
2 SweaterFish The evidence for a universal common ancestor of all current life on Earth is pretty convincing, but that doesn't rule out that there was also multiple origins. The common ancestor is not the same as the origin, it lived much, much later. Some theories of the origin of life suggest that different metabolisms or cellular components originated separately and would have been considered living and evolving on their own, but were adopted over time into a single, more flexible or efficient mosaic organism that was our common ancestor.
1 [deleted] [removed]
1 JereRB I saw a show once. Said that life not only happened, but has happened multiple times. Things in the past happened that killed literally everything: asteroids cracked the crust, worldwide volcanic eruptions, etc. Life happened after and between each one. So could it have happened in multiple locations way back when it first became possible after the latest cataclysm? Given that life seems to occur as soon as environmental conditions allow, it's very possible, if not highly likely. The fact that everything alive now shares a common ancestor just means that those other organisms met our forebears...and lost.
-1 chodumadan that carbon is the base of life on earth could be due to environmental factors like temperature. if the temperature were different - like it is on other planets - it is possible that some other element would be the base of life.
13 0 Kenley Furthermore, it's conceivable that there were multiple origins of life early on, but the others didn't "make it." Perhaps, for whatever reason, they were less efficient at metabolism or reproduction than life-as-we-know-it, so they weren't able to get a foothold.
11 0 t_mo 'Possible' is a tricky word in origins biology. For Archae and Bacteria to have *no ancestor in common* would imply a profound level of convergence, a frequentist statistical probability approaching zero. At a certain point in development we have to start asking 'what does an ancestor actually look like', and we have to enter into a discussion of abiogenesis or some other theoretical origin point. We can't pinpoint specifics in the pre-cellular ancestors, and what that would actually look like depends on which perspective you take on likely biological origins. However, whatever we presume for the sake of discussion to be the pre-cellular ancestor of bacteria/archae, we know that it has a very limited number of forms and features. If those forms and features share so much in common (bound by membrane, pre-RNA features of replication, etc) we have to reconsider what the statement of 'two distinct ancestors' would look like even from a theoretical perspective, *could* they be sufficiently distinct while still sharing sufficient features to produce unicellular life as similar in form and function as archae/bacteria, or are we really just looking at two slightly different versions of the same replicating system? As with a lot of questions in origins biology, the discussion is mostly philosophical and not very practical.
6 0 Rather_Dashing All current life on earth came from a common ancestor. We know this because, among many other lines of evidence, we all have the same dna code (with some minor variation). For example the DNA codon 'TCT' codes for a Serine base. There are 64 different codons and they consistently code for the same amino acid bases across the kingdoms. The odds that two separate origins of life would come up with the same code is astronomically low. However if is possible, even likely, that life arose multiple times, but the other lines died out leaving all the life known today descending from a single ancestor.
2 0 rocketsocks Likely, in fact. And some of the earliest forms of life may have intermingled because they were so similar (if they weren't much more than just self-replicating RNA polymers, for example). However, at some point one form of life became advanced enough to outcompete all the others by a significant margin, and that became the "last universal common ancestor" (or LUCA) for all current life on Earth. It's possible that abiogenesis type events continue to occur on Earth today but aren't able to get a foothold on a planet with abundant life already. As far as we can tell all life on Earth has a common ancestor, however. We can be pretty certain of this due to the similarities in the core DNA -> RNA -> protein genetic coding pipeline. There is great similarity in the fundamental molecular machinery of all life. They share the same 3-nucleotide codon length, the translation table between codons -> amino acids is remarkably similar across species, the ribosomes, t-rnas, etc. which facilitate translation of RNA to amino acid sequences is also remarkably similar. There are far too many similarities in those core mechanisms to be due to either chance or convergent evolution, which points to a common evolutionary lineage between all life on Earth.
2 0 SweaterFish The evidence for a universal common ancestor of all current life on Earth is pretty convincing, but that doesn't rule out that there was also multiple origins. The common ancestor is not the same as the origin, it lived much, much later. Some theories of the origin of life suggest that different metabolisms or cellular components originated separately and would have been considered living and evolving on their own, but were adopted over time into a single, more flexible or efficient mosaic organism that was our common ancestor.
1 0 [deleted] [removed]
1 0 JereRB I saw a show once. Said that life not only happened, but has happened multiple times. Things in the past happened that killed literally everything: asteroids cracked the crust, worldwide volcanic eruptions, etc. Life happened after and between each one. So could it have happened in multiple locations way back when it first became possible after the latest cataclysm? Given that life seems to occur as soon as environmental conditions allow, it's very possible, if not highly likely. The fact that everything alive now shares a common ancestor just means that those other organisms met our forebears...and lost.
-1 0 chodumadan that carbon is the base of life on earth could be due to environmental factors like temperature. if the temperature were different - like it is on other planets - it is possible that some other element would be the base of life.