The universe is said to be around 23% dark matter, 72% dark energy and 5% ordinary matter. If we don't know what dark matter and dark energy are, where do the percentages come from? | AskScience Blog

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Thursday, March 8, 2018

The universe is said to be around 23% dark matter, 72% dark energy and 5% ordinary matter. If we don't know what dark matter and dark energy are, where do the percentages come from?

The universe is said to be around 23% dark matter, 72% dark energy and 5% ordinary matter. If we don't know what dark matter and dark energy are, where do the percentages come from?


The universe is said to be around 23% dark matter, 72% dark energy and 5% ordinary matter. If we don't know what dark matter and dark energy are, where do the percentages come from?

Posted: 07 Mar 2018 12:27 PM PST

Edit: I just want to clarify, I'm aware of what dark matter and dark energy are. I'm by no means an expert, but I do have a basic idea. I'm wondering specifically how we got those particular numbers for them.

submitted by /u/Luxray1000
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Would rain droplets on a lower gravity planet be larger, on average, compared to our own planet?

Posted: 07 Mar 2018 11:34 AM PST

Like a gravitational field, does a strong electromagnetic field also affect the flow of time?

Posted: 08 Mar 2018 03:32 AM PST

Does it also dilate time or work in the opposite way and speed it up?

submitted by /u/DeltaEmerald11
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Does light travel forever?

Posted: 08 Mar 2018 03:03 AM PST

Does the light from stars travel through space indefinitely as long as it isn't blocked? Or is there a limit to how far it can go?

submitted by /u/cilan312
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How do shockwaves affect small organisms on the cellular scale?

Posted: 07 Mar 2018 08:30 PM PST

I.e. shockwaves from explosives affecting things like amoebas, bacteria, etc

submitted by /u/PETApitaS
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Why did they use the krypton-86 atom to measure the metre?

Posted: 08 Mar 2018 05:15 AM PST

Idk if this should be in r/history, but what was so special about krypton to warrant the "…the length equal to 1,650,763.73 wavelengths in vacuum of the radiation corresponding to the transition between the levels 2p10 and 5d5 of the krypton 86 atom."?

submitted by /u/curryhalls
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Can we see the emitted photons from atoms of the objects when the electrons of those atoms move to a lower energy level?

Posted: 07 Mar 2018 09:22 AM PST

I have learned that things have colors when the electrons absorb the photons with particular wavelengths and the rest (photons that are not absorbed) will go to our eyes and make us see colors. And when the electrons lose energy they emit the photons which has the same wavelengths as when they're absorbed. So my question is: Do we actually see the colors from the emitted photons? And if so it must change the color of the object, right? This question has been bugging me for ages, please shed a light for me.

submitted by /u/Redral99
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When we say something doesn't have a smell, like carbon monoxide, does that mean (a) ordinary people can't smell it, (b) humans lack the ability to smell it, or (c) it actually doesn't give off a smell detectable by anything?

Posted: 07 Mar 2018 06:16 PM PST

And if the answer is C, how is it physically possible for something to not have any smell at all?

submitted by /u/graaahh
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The larger the telescope, the deeper into space we can see. Is the same true for microscopes? Can bigger microscopes see even smaller particles?

Posted: 08 Mar 2018 03:57 AM PST

Why isn't calprotectin used to screen for colon cancer in people younger than 50?

Posted: 07 Mar 2018 07:37 AM PST

I've recently found out about calprotectin from my doctor and he said it can be used to show the difference between functional and organic colon disease (cancer, chron's etc.). It's a cheap test, why not get tested once a year as colon cancer is one of the most common cancers? It's the risk of cancer before the age of 50 too small to make a difference or is it a cost issue?

submitted by /u/lezze
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How do large rockets balance in the first few seconds of flight, before aerodynamics play a part?

Posted: 07 Mar 2018 10:13 PM PST

How does the moon Enceladus have water?

Posted: 07 Mar 2018 12:31 PM PST

So I've read briefly that for a planet to sustain liqiud water, it must be in the CHZ, however Enceladus is way out of this zone. How is this possible?

submitted by /u/HighOnPies
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[Medical] Do wounds on patients on life support(medically declared dead) heal?

Posted: 07 Mar 2018 02:24 PM PST

Lets say a patient gets in to a car crash and damages their head. Black eyes and bruises. They die in the E.R. and are on life support. Will their physical injuries eventually heal?

submitted by /u/MaulerX
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Is there a difference between SIO2 and Silica Silylate?

Posted: 07 Mar 2018 07:24 PM PST

I was looking at the ingredients of a hair volumizing product and the top ingredient was Silica Silylate. All I could find online says Silica Silylate is nanoparticles from quartz.

submitted by /u/main_motors
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How much do cows actually contribude to greenhouse emissions?

Posted: 07 Mar 2018 05:32 PM PST

I have tried to search this up and not only do I not find anything consistent (some claim it's close to 50% others that is lass than 20%)

And no source seems to make a distinciton in between brute greenhouse emissions production and net emissions.

Since all carbon cows produce must first have come from a plant, which in turn must have absorbed it fromt he environment, how much a cow produces is not relevant, what matters is how much they affect the contenctration of greenhouse gasses in a given period. Since ultimately for every atom of carbon they expell the consumed it first.

I'd like a reliable source that explains in detail full cycle of production of meat. How much does it ACTUALLY affect the conentration fo greenhouse gasses in the atmoshere?

submitted by /u/camilo16
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Would altering the physical characteristics (e.g. pureeing) food affect it’s available calories or nutritional content?

Posted: 07 Mar 2018 06:49 PM PST

Basically I'm think in terms of either eating a carrot or steak as-is, versus throwing them in a blender. You would still be ingesting the same content, it would have just been broken down physically. (Excluding heat or cooking as a factor.)

Would this impact our effective calories or nutritional benefit during digestion in any way?

submitted by /u/unthused
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How do polarizing filters “know” the orientation of incoming photons?

Posted: 07 Mar 2018 12:59 PM PST

Is the gravitational attraction pulling us constantly with the same amount of force in different locations or it differs, what about if you're on a boat in the ocean?

Posted: 08 Mar 2018 01:31 AM PST

How can we know that when we pull quarks apart the energy exerted creates a stronger bond?

Posted: 07 Mar 2018 07:17 PM PST

I'm watching "The Inexplicably Universe" and it was just said that when we pull quarks apart the energy used to pull them apart and if separated two new quarks replace the removed quarks instantaneously. Right before that Tyson said that electrons are so small we can't see them and quarks are obviously significantly smaller. How can we know what happens to the quarks at such a small scale we can't see?

submitted by /u/Schnectadyslim
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