| Can someone who has photosensitive seizures have a seizure by blinking really fast? Posted: 07 Dec 2019 05:49 PM PST |
| Do sound waves bend when they enter a different medium? Posted: 08 Dec 2019 03:25 AM PST |
| Does the temperature of the air affect the loudness of sound? Posted: 07 Dec 2019 11:58 PM PST Say you fire a gun in a hot humid environment, will it be louder or slightly less louder? What about firing a gun in a subzero environment? Will it be louder or the same? submitted by /u/MrBig562 [link] [comments] |
| Are stars closer to the center of our galaxy generally larger the ones farther away ? Posted: 08 Dec 2019 01:34 AM PST Title basically. Is it the same for other kinds of galaxies, wouldn't larger stars usually gravitate to the centre of all galaxies ? submitted by /u/raggikomm [link] [comments] |
| How is the CMB be the most distant thing we can see when there is a cosmic horizon? Posted: 07 Dec 2019 10:51 PM PST Hi r/askscience! I'm watching the PBS Spacetime series on the Cosmic Microwave Backround and something's nagging at me that I was hoping you could resolve. I get the gist of the following facts: - Because of the speed of light, when we look out into space we are actually looking into the past. So when we're looking at something that's a billion light years away, we're really seeing it as it was a billion years ago.
- The universe is expanding, and the further into the past we look, the faster the objects we see are moving away from us (Hubble's law right?). This creates a cosmic horizon; there are objects that are so far away, that they are moving away from us so quickly that their light will never have a chance to reach us, the universe is expanding too quickly for us to ever see them.
- The most distant thing we can see is the Cosmic Microwave Background, a frozen radio (err.. microwave?) emissions from when the universe was in it's infancy some 13.2 billion years ago (or whatever).
When I think about it, points two and three seem to be in conflict with each other. It seems like the CMB will always be the most distant thing we can see since the light it released was the first light ever produced in our universe. So a billion years ago the CMB was the most distant thing able to be detected, and a billion years from now the CMB will still be most distant thing view-able, since the the universe began releasing light more or less everywhere at once, and so we're seeing today the CMB at a distance of 13.2 B light years, a billion years ago one would be able to see it at a distance of 12.2 B, and a billion years from now one will be able to view it at a distance of 14.2 B light years. But doesn't this contradict the idea of a cosmic horizon? If, in the future, we will actually be able to see less of the universe because it is expanding faster, wouldn't the furthest away objects we see actually be closer to us today than they will be (lets say) a billion years from now? Wouldn't the CMB "we" see in a billion have had to have been released from a point closer to us than the CMB we are seeing today since the universe is expanding and today's most distant objects will have fallen behind the cosmic horizon, and we would therefore have seen it already, and not a billion years from now? My apologies if I'm being a bit inarticulate, even speaking about this in a way that makes sense to me is difficult, so let me know if I can clarify any part of my question. Please ELI've taken an intro to physics and a few calc classes, along with having watched some PBS Spacetime episodes. Thank you all in advance! submitted by /u/Confusedphilomath [link] [comments] |
| How is a breed of dog declared hypoallergenic? What causes certain breeds to be and others not? Posted: 07 Dec 2019 09:04 PM PST I ask because according to Dr. Google, Yorkshire Terriers are hypoallergenic... however I have been around 4 yorkies in my life and all 4 times I've had awful allergic reactions - and I'm not allergic to (other) dogs. I have 1 inside dog currently, and had 5 dogs (3 indoor) at one point with all different types of coats; I never even had a sniffle. But the supposedly hypoallergenic Yorkies make me sneeze and itch and my eyes swell almost shut. My best friend just got one, and I can no longer go to her house without taking a Benadryl first. (I also am severely allergic to cats if that matters). So how do scientists declare a specific breed "hypoallergenic." submitted by /u/friendispatrickstar [link] [comments] |
| How does a single propeller plane not roll? Posted: 07 Dec 2019 08:45 PM PST So, suppose an airplane with a single propeller spinning in a clockwise direction. So, by the conservation of angular momentum, the body of the plane must spin in anticlockwise direction. How do plane resist that and fly straight. submitted by /u/colddroid69 [link] [comments] |
| Would an object that is vulnerable to oxidizing (Apple slices,copper,etc.) oxidize in liquid and solid oxygen like it does in air? Posted: 07 Dec 2019 06:03 PM PST |
| Follow up on "Why is glass transparent". Why are the energy gaps between energy levels different in sand and glass? Posted: 07 Dec 2019 10:34 PM PST Glass is transparent as the energy needed to move an electron to a higher energy state is greater than visible light (UV light is absorbed), so visible light passes through, making glass transparent. However in sand, visible light is absorbed. Why are the energy gaps between energy levels of atoms different between sand and glass? submitted by /u/redgreenballoondrop [link] [comments] |
| What would happen if two galaxies collided? Posted: 08 Dec 2019 01:33 AM PST Would it be an all out smash-fest with all the planets and stuff or would everything combine into a super galaxy? submitted by /u/iEatBabyLegs [link] [comments] |
| Are plasmid origins of replication nonspecific? Posted: 07 Dec 2019 08:14 PM PST For example, if I made a recombinant plasmid using a pAMP ori with a pKAN gene for kanamycin resistance, would it be transcribable? submitted by /u/64145 [link] [comments] |
| Are halogen ions (Cl-, I-) toxic to microbes or is it just the elemental forms (Cl2, I2) ? Posted: 07 Dec 2019 06:50 PM PST |
| How is the voltage controlled in a linear accelerator? Posted: 07 Dec 2019 08:56 PM PST I've been wondering about this for a while, and I've tried looking it up but still don't understand it too well, so I was hoping someone here would be able to explain it in simpler terms to me. I think I understand the basic concepts of how a linear accelerator works: - Charged particles are separated (ie, the electrons are removed from hydrogen atoms to be left with protons)
- The protons are attracted towards a negatively-charged electrode
- Once the protons pass through that electrode, the voltage is reversed - the electrode they just passed through becomes positive, and the next electrode becomes negative. So they accelerate towards the negative electrode.
- This is repeated through a series of electrodes. Each time, once they pass through, the voltage is reversed so they are attracted towards the next electrode, and each time, they speed up more.
My question is, how do they reverse the voltage between the electrodes at exactly the right time, considering how fast those protons must be moving and the fact that they are accelerating, not moving at a constant speed? Thanks. submitted by /u/skinny_bitch_88 [link] [comments] |
| Do veins grow in the same configuration in most/all people? That is, will my neighbor's veins branch in the same places/same way as mine? Posted: 07 Dec 2019 11:29 AM PST Obviously human bodies have variation, but most people are born with two eyes, two hands, ten fingers, etc. which are all in the same places. Does this apply to veins, too, or do they vary in the number of places they branch/particular places they branch? I guess this question can apply to other parts of the body, too, like the nervous system... submitted by /u/HelloOrg [link] [comments] |
| Does every infinite sum of rational numbers have a rational solution? Posted: 07 Dec 2019 06:39 PM PST So I am aware that every finite sum of rational numbers has a rational result and that every rational number can be expressed as an infinite sum of rational numbers, but I'm wondering if the inverse is true, does every infinite sum of rational numbers yield a rational result? submitted by /u/Only_A_Friend [link] [comments] |
| A clinostat is generally used for experiments involving bacteria and plants. Could it be used to observe crystal growth or the molding of metal alloys in microgravity? Posted: 07 Dec 2019 02:14 PM PST |
| Can atmospheres be "wiped away" by solar wind on a planet with no electromagnetic field? Posted: 07 Dec 2019 01:16 PM PST |
| Do animals receive different treatment from their mother because of gender? Posted: 07 Dec 2019 10:55 AM PST |
| Why do dreams contain a sense of motion even though our bodies/minds/inner ear aren't moving? Posted: 07 Dec 2019 06:13 AM PST Last night i had a dream i was on a jet with a crazy pilot who kept doing loops and flips and all kinds of manuevers. I could feel my stomach bottoming out, my body being tossed side to side with the G-forces of the turns and such. I distinctly remember focusing on the horizon and trying to orient myself with what I knew in order to fight the "upside down" sense. How does the body/brain at rest recreate the feelings of motion in a dream? submitted by /u/drummer_San [link] [comments] |
| Why do some cars have faster acceleration but lower top speed and other cars have lower acceleration and higher top speed? Posted: 07 Dec 2019 02:46 PM PST |
| Are black holes hot? And do they emit any heat/heat radiation? Posted: 07 Dec 2019 07:59 AM PST |
