Ask a Physicist!

[Lightknight]

Near light travel:

I have a few questions on the properties of matter traveling at near light speeds:

1. Durability:
From what I've been told, the forces that hold objects together would break down at light speed. I was wondering if the objects traveling at those speeds really experience those forces since the idea is that they'd be in a vacuum and that they would increase to that speed incrementally. So relative to us they'd be going the speed of light but relative the them we're just moving really slow. I would think that the objects traveling at that speed would be shielded from feeling the effects of that speed in the same way we are shielded when we are in a car from really feeling like we're going that fast.

2. The interior of a vehicle traveling at near light speed:
If my question from number 1 is answered in the affirmative, then if you were inside of a vehicle traveling at light speed. What would happen if you shone a flashlight within the vehicle or tossed a ball. Would it reach the other wall? I know this is a question traditionally asked as though the flashlight were on the front of the vehicle so I thought I'd ask from the inside of the vehicle. Like how if I drop a ball inside a car it falls mostly straight down but outside the window it appears to fall behind the vehicle (I presume due to wind resistance). Or maybe within a closed system that has reached that momentum the distance from the light source to the other wall isn't seen as traveling faster than the speed of light whereas being outside of the environment would be. I'm just having a hard time considering the idea that I could technically toss a ball within a car traveling at 100 miles per hour and from the outside it look like I'm tossing the ball at 101+ miles per hour. It seems like relative speeds should still be relevant here.

3. Faster than light travel.
When they say that if an object is traveling faster than the speed of light that it would actually be traveling backwards through time, doesn't that really only mean that the object would "appear" to be traveling back in time in relation to us but wouldn't literally be getting someplace before they left? For example, I see light as a sequence of photos stacked in an ordered pile. If you travel faster you just speed up the frames that they go past you (so if you approached a planet, it would appear to age faster as your speed increased but only because you are traveling faster and if you left the planet it would appear to be getting younger even though it only appears that way). The hypothesis here is that if you traveled faster than light and looked back that you would see yourself going backwards. But wouldn't this just be your appearance going backwards rather than you literally going back in time?

I just don't get how we have a universe where instantaneous teleportation of information exists (quantum entanglement) but somehow traveling at an ultra fast rate of speed means that you're traveling more than instantaneously when light itself isn't anything close to instantaneous. I mean, the claim here would imply that if light traveled only 1 unit of distance faster per second that it would then be traveling backwards in time, right? Yet we measure distant objects in light years which should discredit the notion that they are on the cusp of reaching destinations before they were sent out. Right? There has to be a trick in what people mean by "time travel". Surely every object in space has its own relative "now" and no matter how fast we travel between them we can't change the object's "now" in relative to our "now". We can only make it appear like we're altering it when we aren't really. Also, at no point would we be able to look in any direction and see our future selves, only our past.

4. Permeation of light photons in space.
Should space be absolutely full of light photons? We can see stars from thousands of light years away from any point in space which should mean that photons are reaching our point of view. You'd think there'd be more detection of this or that they'd even interact with one another at such great numbers... right?

 

[Slenn]

What I meant about the Higgs Boson is that seems odd that a type of particle would create the effects associated with individual perception, given the discoveries I mentioned--or is the idea that perception influences the behavior of the particle like it seems to affect electrons?

The Higgs Boson is a measurable particle, like any other particle. It's also what's called a scalar particle, or a particle with no spin. This means that it doesn't have any angular momentum associated with it. Scalar particles are the beginning of introductory quantum mechanics classes, where observation effecting the behavior of particles is examined (what you were concerned about). So it's not too unusual. I hope that answered what you were talking about.

I also wonder: if such artificial gravity is possible, is a diameter of 100 feet sufficient? I know that if the rotating spaceship is too small, the astronauts will feel like they are being pulled in two directions at once. Arthur C.Clarke made that mistake in 2001: A Space Odyssey--I usually prefer my fantasy, sci fi, cartoons, etc. stories to be unrealistic, but Clarke and Mike Judge are exception.

To mimic 1 g, a 100 ft (~30 m) diameter space station would have to be rotating at 40.11 ft/s (12.23 m/s) at the edge. Such a speed is not inconceivable for any space station to muster, but it's also quite fast. It would be advisable to make a space station that's much wider.

What does there being an equal amount of matter and antimatter in the universe mean: Are there structures like planets and stars made of antimatter, or are they just random floating particles? Were a lot of sudden cataclysmic events like supernovae, black holes opening, gamma ray bursts, or something like those to destroy a large portion of the matter universe, could the decreased gravity of the matter cause it to be pulled in by the gravity of the antimatter?

Well, presumably all the bulk antimatter is gone. We originally assumed that at the beginning of the universe there must be an equal amount of antimatter to matter. But it turns out, we're finding more matter than antimatter. So somehow there's an inequality between the two species. The events that you're talking about aren't necessarily connected with the destruction of matter. Supernovae is the ejection of the fuel that's left over from a large star. And they also are responsible for most of the heavy elements beyond iron (element 26). Black holes are powerful, but they're not wide spread enough in the universe to cause a significant drop in matter. Same goes for gamma ray bursts, and that won't destroy matter either since it's only radiation and not antimatter.

Everything on Earth accelerates down from gravity at the same rate no matter what their mass is. But decreasing the gravity of one object does not necessarily effect the gravity of the other object. My mass has no effect on the gravitational field that's exerted by Earth.

Are we on the verge of the heat death of the universe? I remember an Arthur C. Clarke story from the '60s or '70s saying that space was at 3 Kelvin, a science class telling me that it was 2.75 Kelvin, and I think I heard someone say recently that it was at 2.5 Kelvin.

What you're referring to are measurements that are repeated over the years. Through more studies and accurate instruments, the number on the known average temperature of the universe is likely to change just from a change in what tools we use. But as the Ouroboros stated, we're no where near a heat-death. That won't come for 100's of trillions of years.

 

[TheRaider]

why does dark travel faster than light?

Could you elaborate where you found this postulation? I might be able to help if you gave me a bit more context.

Get a really powerful torch. Shine a moon. Put your finger in front of torch so it casts shadow on moon. Move finger and the shadow should move faster than light.

 

[MrFalconfly]

why does dark travel faster than light?

Could you elaborate where you found this postulation? I might be able to help if you gave me a bit more context.

Get a really powerful torch. Shine a moon. Put your finger in front of torch so it casts shadow on moon. Move finger and the shadow should move faster than light.

I think this video would be relevant.

 

[renegade7]

What's your field going to be? Are you planning on teaching, doing academic research, or private/public sector research?

I'm starting my second year of graduate school, my focus right now is towards condensed matter, but it's still pretty early on and I could just as well see myself ending up in computational physics/DSP or material science. I'm also fairly well-versed in some relativity/astrophysics related things because I double-majored in math in college and my concentrations (the 5-semester elective sequences we had to pick) were differential geometry and modern algebra. Do you think there's still time to explore, or should I commit myself to one ASAP? Do you think a gap year or semester to think about what I might want to do might be a good idea?

Have you yet had to deal with the crank emails? I don't know what the general experience among other physicists is with this, but I'm studying at a university that's well-known for climate research so we get mass emails on a regular basis from people demanding we give them the "real data" or some such thing, and also the occasional conspiracy theorist. More recently we've had some people from Wikileaks and one of the conspiracy theory forums who are absolutely certain that we're suppressing research on that "emDrive" thing from a couple months ago.

Do you have a favorite textbook? I personally really appreciate good textbooks, and I pretty much always have Shankar or Kreyszig close at hand, but I've seen that this can be a surprisingly divisive subject.

 

[Slenn]

Get a really powerful torch. Shine a moon. Put your finger in front of torch so it casts shadow on moon. Move finger and the shadow should move faster than light.

It takes about 1 second for light to reach the moon. If I were to cast a shadow on the moon using a powerful flashlight and my hand, that information would not reach the moon until 1 second later. And the same thing goes for when my hand moves away from the flashlight.

What the video refers to is actually something that is talked about in EM classes. In EM waves, it's the group velocity of a collection of waves that moves at the speed of light, while the phase or wave velocity will often travel faster than this speed. The wave velocity is essentially the speed at which the waves are moving inside the wave group. And this pops up in discussions concerning constructive and destructive interference where two waves with two different frequencies will create peaks and troughs that are moving faster than the collection of waves themselves.

But that only means that the regions of destructive interference are also moving at the same speed as the regions of constructive interference.

A nice graphic to show what I'm talking about is shown here:
https://en.wikipedia.org/wiki/Group_velocity

 

[retsupurae yahtsee]

That whole shadow on the moon thing does raise some questions, though: Doesn't the light have to be displaced to cast a shadow? Is it being moved faster than the speed of light when you pass over it? There would have to be particles shining on the moon to be seen because pure energy would be perceived as static, and the moon is about two light seconds away from us but we can see it the moment we look at it and cast a shadow immediately--what does this mean? I remember my father had an idea that perhaps different places in distant space are different points in time because we can see things many lightyears away and time travels at the speed of light, but that seems to make no sense.

 

[Slenn]

1. Durability:
From what I've been told, the forces that hold objects together would break down at light speed. I was wondering if the objects traveling at those speeds really experience those forces since the idea is that they'd be in a vacuum and that they would increase to that speed incrementally. So relative to us they'd be going the speed of light but relative the them we're just moving really slow. I would think that the objects traveling at that speed would be shielded from feeling the effects of that speed in the same way we are shielded when we are in a car from really feeling like we're going that fast.

I'm a little confused. Are we talking about a space ship that's in a vacuum in the first place? And what are you referring to by "increasing to that speed incrementally?" Are you assuming that the ship is increasing velocity at a constant rate?

2. The interior of a vehicle traveling at near light speed:
If my question from number 1 is answered in the affirmative, then if you were inside of a vehicle traveling at light speed. What would happen if you shone a flashlight within the vehicle or tossed a ball. Would it reach the other wall? I know this is a question traditionally asked as though the flashlight were on the front of the vehicle so I thought I'd ask from the inside of the vehicle. Like how if I drop a ball inside a car it falls mostly straight down but outside the window it appears to fall behind the vehicle (I presume due to wind resistance). Or maybe within a closed system that has reached that momentum the distance from the light source to the other wall isn't seen as traveling faster than the speed of light whereas being outside of the environment would be. I'm just having a hard time considering the idea that I could technically toss a ball within a car traveling at 100 miles per hour and from the outside it look like I'm tossing the ball at 101+ miles per hour. It seems like relative speeds should still be relevant here.

Inside the vehicle, the bubble that allows for the ship to travel at the speed of light would probably mean that the beam of light inside the ship moves normally.

Your analogy with the car needs a little more clarification. Are you suggesting that the scenario with the wind resistance is when the ball is tossed out of the window? Or are you referring to an observer watching someone drop a ball inside the car?

3. Faster than light travel.
When they say that if an object is traveling faster than the speed of light that it would actually be traveling backwards through time, doesn't that really only mean that the object would "appear" to be traveling back in time in relation to us but wouldn't literally be getting someplace before they left? For example, I see light as a sequence of photos stacked in an ordered pile. If you travel faster you just speed up the frames that they go past you (so if you approached a planet, it would appear to age faster as your speed increased but only because you are traveling faster and if you left the planet it would appear to be getting younger even though it only appears that way). The hypothesis here is that if you traveled faster than light and looked back that you would see yourself going backwards. But wouldn't this just be your appearance going backwards rather than you literally going back in time?

You have the right idea. You're only seeing your appearance twice, one going backwards, and the other going forwards.

I just don't get how we have a universe where instantaneous teleportation of information exists (quantum entanglement) but somehow traveling at an ultra fast rate of speed means that you're traveling more than instantaneously when light itself isn't anything close to instantaneous. I mean, the claim here would imply that if light traveled only 1 unit of distance faster per second that it would then be traveling backwards in time, right? Yet we measure distant objects in light years which should discredit the notion that they are on the cusp of reaching destinations before they were sent out. Right? There has to be a trick in what people mean by "time travel". Surely every object in space has its own relative "now" and no matter how fast we travel between them we can't change the object's "now" in relative to our "now". We can only make it appear like we're altering it when we aren't really. Also, at no point would we be able to look in any direction and see our future selves, only our past.

What do you mean by "ultra fast rate of speed"?
I'm also not sure what you're talking about with the light year analogy. "they are on the cusp." Who's "they"? The light waves?

4. Permeation of light photons in space.
Should space be absolutely full of light photons? We can see stars from thousands of light years away from any point in space which should mean that photons are reaching our point of view. You'd think there'd be more detection of this or that they'd even interact with one another at such great numbers... right?

The thing is, space is big. Big. The distance from the Earth to the Sun is peanuts compared to the distance between the sun and the nearest star system, Alpha Centauri. And that distance reduces the power at which we receive light from them.

 

[Slenn]

What's your field going to be? Are you planning on teaching, doing academic research, or private/public sector research?

I'm starting my second year of graduate school, my focus right now is towards condensed matter, but it's still pretty early on and I could just as well see myself ending up in computational physics/DSP or material science. I'm also fairly well-versed in some relativity/astrophysics related things because I double-majored in math in college and my concentrations (the 5-semester elective sequences we had to pick) were differential geometry and modern algebra. Do you think there's still time to explore, or should I commit myself to one ASAP? Do you think a gap year or semester to think about what I might want to do might be a good idea?

Have you yet had to deal with the crank emails? I don't know what the general experience among other physicists is with this, but I'm studying at a university that's well-known for climate research so we get mass emails on a regular basis from people demanding we give them the "real data" or some such thing, and also the occasional conspiracy theorist. More recently we've had some people from Wikileaks and one of the conspiracy theory forums who are absolutely certain that we're suppressing research on that "emDrive" thing from a couple months ago.

Do you have a favorite textbook? I personally really appreciate good textbooks, and I pretty much always have Shankar or Kreyszig close at hand, but I've seen that this can be a surprisingly divisive subject.

As I stated in my first post, right now I'm doing nuclear physics research. And it's going to be that way until I finish. I had a good long talk with my aunt in New Mexico about what to do after graduate school. The bottom line out of that whole discussion was to keep the options open. Teaching high school level physics would be ideal in terms of social interactions, but the pay is shoddy. Going into industry where I use my computer science skills is also another option. And lastly a post doc position could be a thing as well.

The physics graduate student body also had a nice discussion with the head of the department not too long ago about this. What he was saying was that there is no pressure for anyone to push themselves towards a post doc position or a job position outside of graduate school if and when it does end. There is no rush. But there are resources available to help prepare you before you exit grad school. I would also check with your department head and hear what they have to say. I would say try and find as many options as you can. Life is always changing, so it's good to look into multiple things. Don't take a break from graduate school unless it's a serious emergency. It's just that a lot of schools will want a nice reason why you're needing a reprieve, and you'll have plenty of time to figure out things while you're in grad school. You'll also be acquiring awesome job skills while attending said school.

I've never had crank emails of the type you're talking about. But I am ever vigilant of those emails. Data theft from cyber attacks are a real threat.

Favorite textbook? Anything by Griffiths, especially his Introduction to Electrodynamics. His mode of speech was very human and approachable. Jackson was always gotten flack that he's really dense with his descriptions and equations of things. But he at least tackles subjects that are not suitable for the undergrad level.

 

[FPLOON]

Is bad physics still better than no physics?

You mean physics in the real world, or people studying physics?

More along the line of fiction in general... Probably should have made that distinction...

Which part of the personified body should we really grab "life" from?

I have no idea what you're talking about. *shrug* Could you elaborate on what you mean by "personified body"?

When certain people say the phrase "Grab life by the balls", are they sure that's the best place to grab life from if we're truly personifying "life" as an actual person? If not, then which part of the body should we grab "life" from?

Are there any good physics-based raps?

Spoiler: The only one I could think of is this.

I got to be honest... That shit's dope...

Admittedly, I'm not into rap. If you really want some awesome science based music, Melody Sheep does some awesome mixes.

Spoiler: This is my favorite

I love Melody Sheep's music mixes... and not just because I shared some of the Symphony of Science songs with my formal Calculus teacher and got unneeded extra credit in the process...

 

[the December King]

Apologies if this has already been asked, as I'm short on time just now, but I thought I'd ask, having no scientific background, but a keen respect for those that do:

Is it possible that black holes are actually not 'collapsed stars', but merely the centers of many millions of gravity wells all being generated by huge groups of matter (stars)? Put in succinct terms, could black holes exist without the galaxies that they typically seem to form at the centers of?

 

[Slenn]

Apologies if this has already been asked, as I'm short on time just now, but I thought I'd ask, having no scientific background, but a keen respect for those that do:

Is it possible that black holes are actually not 'collapsed stars', but merely the centers of many millions of gravity wells all being generated by huge groups of matter (stars)? Put in succinct terms, could black holes exist without the galaxies that they typically seem to form at the centers of?

That is a good question. To go over black hole formation, I'll need to describe star evolution. The type of death for a star is pretty much predetermined the moment the star is formed. Everything kind of depends on the initial mass. A star 0 to 10 times the mass of the sun will go the way of the nebula, shedding off its outer layers gently until it becomes a white dwarf (the former core of the sun). A star 10 to 20 times as massive as the sun, will explode in a supernova. And a star 20 to 30 times as massive gets crushed by its gravity so much that it creates a dent in space time, a black hole.

A black hole could exist outside the center of our galaxy. But the common belief is that there is also a black hole at the center of the Milky Way. If enough mass from stars crushes inward, a black hole can form. You're correct in assuming that black holes do not just form from collapsed stars, but also just lots of mass that's been crushed by gravity.

I hope this helps.

 

[Slenn]

along the line of fiction in general... Probably should have made that distinction...

Well it depends on the genre. In fantasy I don't really expect there to be scientific explanations. Harry Potter does not need quantum mechanics involved. A sci fi novel like Foundation is going to need some scientific terms. And Isaac Asimov had some scientific background. If there's less scientific terminology in a futuristic setting, then it becomes more fantasy, much like Star Wars. So you can make something good with either or. What is bad is when people elicit scientific terms without doing any research as to what they're saying. It just makes them look foolish.

Which part of the personified body should we really grab "life" from?

Now that I know what you're talking about... the whole body bro. Everything is needed in your life, and your body should be taken care of.

That whole shadow on the moon thing does raise some questions, though: Doesn't the light have to be displaced to cast a shadow? Is it being moved faster than the speed of light when you pass over it? There would have to be particles shining on the moon to be seen because pure energy would be perceived as static, and the moon is about two light seconds away from us but we can see it the moment we look at it and cast a shadow immediately--what does this mean? I remember my father had an idea that perhaps different places in distant space are different points in time because we can see things many lightyears away and time travels at the speed of light, but that seems to make no sense.

Slow down there cowboy...
See my response to the shadow on the moon post. The information of the shadow existing doesn't come to the moon until 1 second after a person puts their hand in front. Imagine a hose with a nozzle that makes a somewhat fast stream of water, and it's pointed at a brick wall. At some time, someone puts their hand in front of the stream of water. But this doesn't stop the water that's already in front of the hand. It will keep traveling until it hits the wall.

Now imagine that the light is replacing the water, and the hose is replaced with a torch/flashlight.

 

[Rattja]

What are your thoughts on teleportation?

Been thinking about it for a while now, and been wondering in what other way it could possibly be done (if any) other than the "classical way".
By that I mean if you think about it as a total deconstruction of something, and then reassemble it somewhere else it creates a whole series of problems. Like if you could do it that way, you could in theory also make another copy of said object given you had the materials to do so, as a machine like that would have some kind of blueprint in its memory to reassemble it.

Another thing is that during the deconstructing process I imagine that all the connections in your brain would be broken. If the machine was able to reconstruct that, it would also be reasonable to assume it could change the way it does it and essentially "reprogram" the subject.

 

[retsupurae yahtsee]

How mdo fire tornadoes work? I would thought they were physically impossible since the stem of a tornado is a vacuum, but they have horrifyingly real, so does the tornado use the shit it picks up as accelerant, or does the constant spinning prevent conduction--how does that work?

I remember that in Intuitor's analysis of The Abyss, it said that flooding the world like the underwater monsters almost did at the end would require about 2,100 megatons of force. How many megatons can underwater volcanoes produce? Would it have to happen in specific areas of the world, or could a sufficient level of force anywhere do it? Related question: Can we do anything about supervolcanoes, and how long do you think we have before they erupt and kill us?

How hard is it to create a Foucault pendulum? Could I place a metronome in a plastic bag and put it on a level surface, or would there still be too many outside factors?

What do you think will be the next big leaps in entertainment and technology in general? Are there any fields that you think have the potential for such development, but receive poor funding and research? Most of the things we take for granted now were unprecedented 150 years ago and there have been a lot of interesting discoveries recently, so I am hopeful that things will develop.

Could anything knock the Earth or the sun out of its orbit? How far could the Earth and the Sun be pulled out of their positions before the Earth became uninhabitable?

 

[bauke67]

We typically define elementary particles as particles that cannot be divided up any further. As far we know we have 6 quarks: up, down, charm, strange, top, and bottom. There's 3 leptons, and they each have their own respective neutrino that goes with them: electron, muon, and tauon. And all of those have their own antiparticle.

Then we get into the realm of the mediating particles. There's the photon, which mediates the EM force. The gluon for the strong nuclear force. And the Z0, W+, and W- mediates the weak nuclear force. And most recently we uncovered the Higgs Boson, which helps describe how objects without mass, like the photon, can interact with objects that do have mass.

So that's (6 + 3 + 3)*2 + 1 + 1 + 3 + 1 = 30.

As for the randomness, there's still restrictions. It can't do whatever it pleases, if that's what you're talking about. Light manifesting by itself cannot happen unless there's some interaction that mediates it, otherwise we'd be breaking energy conservation. There's specific rules that are set in place for quantum mechanics. What Schrödinger's equation allows you to do is to figure out the probability distribution as a function of space and time. This lets us estimate the shape of the electron clouds around atoms. With enough math and powerful computers, one can figure out the distribution for a whole molecule like water.

I hope that does answer what you're referring to.

Thank you both that's very helpful, although maybe a bit confusing because you contradict eachother. In the image there is talk of mesons and baryons of which there are 140 and 120 kinds respectively. Are these not elementary particles? As I type this I realise that might be what the image says. They are made of quarks, like the constituents of regular atomic nuclei? Then I have another question about these and the leptons. What sort of things are they and where does one typically encounter them? I think the image tells me that mesons and baryons are things that pop into existance when something causes quarks to break free from the regular constraint of strong nuclear force, is that correct? Do any of these exist for very long? Sorry about the large amount of questions, the subject interests me very much.

 

[vallorn]

We typically define elementary particles as particles that cannot be divided up any further. As far we know we have 6 quarks: up, down, charm, strange, top, and bottom. There's 3 leptons, and they each have their own respective neutrino that goes with them: electron, muon, and tauon. And all of those have their own antiparticle.

Then we get into the realm of the mediating particles. There's the photon, which mediates the EM force. The gluon for the strong nuclear force. And the Z0, W+, and W- mediates the weak nuclear force. And most recently we uncovered the Higgs Boson, which helps describe how objects without mass, like the photon, can interact with objects that do have mass.

So that's (6 + 3 + 3)*2 + 1 + 1 + 3 + 1 = 30.

As for the randomness, there's still restrictions. It can't do whatever it pleases, if that's what you're talking about. Light manifesting by itself cannot happen unless there's some interaction that mediates it, otherwise we'd be breaking energy conservation. There's specific rules that are set in place for quantum mechanics. What Schrödinger's equation allows you to do is to figure out the probability distribution as a function of space and time. This lets us estimate the shape of the electron clouds around atoms. With enough math and powerful computers, one can figure out the distribution for a whole molecule like water.

I hope that does answer what you're referring to.

Thank you both that's very helpful, although maybe a bit confusing because you contradict eachother. In the image there is talk of mesons and baryons of which there are 140 and 120 kinds respectively. Are these not elementary particles? As I type this I realise that might be what the image says. They are made of quarks, like the constituents of regular atomic nuclei? Then I have another question about these and the leptons. What sort of things are they and where does one typically encounter them? I think the image tells me that mesons and baryons are things that pop into existance when something causes quarks to break free from the regular constraint of strong nuclear force, is that correct? Do any of these exist for very long? Sorry about the large amount of questions, the subject interests me very much.

Ahh. Yes, mesons are made of two quarks and baryons are made of 3. They aren't fundamental particles because they can be split further.

And yes, neutrons and protons are baryons, they are the simplest and most stable ones so they are the ones we see most often.

We generally get more exotic mesons and baryons in high energy enviroments only. Places where E=MC^2 can allow energy to become matter. Then, this mass combines to form the particles we see. You can't really separate quarks because the energy required to pull a meson or baryon apart creates new quarks that bond with the separated ones. But you can make new ones that then bind themselves into these two groups.

and no, pretty much everything except for Protons, Neutrons and Electrons decays really rapidly, so rapidly in fact that when it comes to Top quarks and Tau particles and other high mass particles, we can only observe the spray of particles that results from their decay and not the particles themselves. that's why the detectors round particle accelerators are so huge.

As to what are they? They are simply other fundamental particles. They pretty much all follow the same rules except for Strange quarks who have a property called Strangeness that causes them to decay slightly slower than they should (It's still phenomenally fast)

 

[Slenn]

Thank you both that's very helpful, although maybe a bit confusing because you contradict each other. In the image there is talk of mesons and baryons of which there are 140 and 120 kinds respectively. Are these not elementary particles? As I type this I realize that might be what the image says. They are made of quarks, like the constituents of regular atomic nuclei? Then I have another question about these and the leptons. What sort of things are they and where does one typically encounter them? I think the image tells me that mesons and baryons are things that pop into existence when something causes quarks to break free from the regular constraint of strong nuclear force, is that correct? Do any of these exist for very long? Sorry about the large amount of questions, the subject interests me very much.

Nope. Mesons and baryons are not elementary particles, and they are made of quarks. What's shown in the graphic are some of the familiar mesons and baryons that are composed of quarks.

Leptons are categorized as having spin 1/2, which means that there are two spin states that they can have (If you want to know more about spin, just ask me). They also have no color charge, which means they don't interact through the strong nuclear force. They do have flavor, which means they interact via the weak nuclear force.

An example of a lepton is an electron, which is found around nearly every atom. The other two, muon and tau, are a bit harder to find unless you're in a laboratory setting. Same goes for the neutrinos, but the fact that they have no electric charge makes them difficult to detect.

If you read the graphic closely, it says that quarks cannot be found by themselves. This is due to the fact that the strong nuclear force demands that sets of quarks must have neutral color. I mentioned color charge earlier. What this is is an abstract label that physicists assign to quarks. A proton will have three quarks, and one of them will be red, another green, and the third is blue. Their total color is white, or neutral. If you had a meson and you tried to pull away the two quarks, the energy needed would end up creating a third quark. I know it's sort of bizarre.

As for meson and baryon decays? It depends, as their decay lengths can vary. J/Psi, which is a charm-anticharm meson, has a pretty small half life that's a tiny fraction of a second. While neutrons are baryons that have a half life of 800 seconds if left alone by themselves (if in an atomic nucleus, the neutrons last indefinitely.)

I hope that does help!

 

[AngronIsAngry]

Education: European High School Physics - My brain smashed against it and didnt always come out winning, yet I always found Sciences interesting, if not fascinating. "Know what you don't know." kind of deal.

1. Graviton
Is it a thing? Has it a been found or is it still stipulation? Where and how would one "presumably" look for it?
If found, would that turn Gravity into a function of emmittence speed/reach?

2. Space Flight vs. Radiation
To my understanding space is mostly filled with EM-radiation and the occassional hydrogen proton per km³. If that is correct, wouldn't moving at ludicrous speeds (say close to lightspeed) by a big risk due to the amount of radiation encountered over distance for radiation absorbant bio mass (i.E. humans)? Also, wouldnt the hydrogen particles encountered at close to lightspeed become a risky kinetic impact?
I have read that bascially having a large tank of water in front of the movement direction would be a sufficent/good radiation protection. Would that really work?

3. Electricity Generation
It seems to me that most of the major electricity generation is done via pumping heated water through turbines. It seems a bit ludicrous to me that we have to rely on boiling water (via burning fuels, coals, trash or via radiactivity) to spin magnets in coils.
Have there been any rivaling concepts/technologies for electricity generation on that scope and scale?

4. Fourth Space Dimension
That one is a big question mark to me. Is it an actual "thing" or just an intelectual crutch or something else?
Ever since I heard of this and saw the rubber-matt animations of spacetime, I kept wandering if our 3d universe is the skin on an expanding 4d sphere. Which would mean that endlessly walking in the same direction, would make you walk in circles on the spheres skin, there'd be a center from which the universe "bang-ed", black hole might actually be "oriented down" to a center, black matter/energy would be effects from the other side of 4d spacial expansion, ....
am I complete of my rocker?


I hope my thoughts have not completely walked down the wrong path in terms of understanding physics.

 

[Slenn]

What are your thoughts on teleportation?

Been thinking about it for a while now, and been wondering in what other way it could possibly be done (if any) other than the "classical way".
By that I mean if you think about it as a total deconstruction of something, and then reassemble it somewhere else it creates a whole series of problems. Like if you could do it that way, you could in theory also make another copy of said object given you had the materials to do so, as a machine like that would have some kind of blueprint in its memory to reassemble it.

Another thing is that during the deconstructing process I imagine that all the connections in your brain would be broken. If the machine was able to reconstruct that, it would also be reasonable to assume it could change the way it does it and essentially "reprogram" the subject.

My own estimation for a feasible teleporter is using something with space time. Maybe there's a way we'll figure out how to create gateways and that'll mark the beginning of teleportation. So that's another option to keep open.

How do fire tornadoes work? I would thought they were physically impossible since the stem of a tornado is a vacuum, but they have horrifyingly real, so does the tornado use the shit it picks up as accelerant, or does the constant spinning prevent conduction--how does that work?

A tornado is a moving column of air, which means there's plenty of room for a fire to exist inside it. Firestorms are a concern for firefighters because it's a self sustaining fire in the air. Fire tornadoes are self sustaining in the same way. Both use gradients of hot to cooler air to draw in oxygen to perpetuate the flame. Gradients of hot to cold air are what create wind in the first place. This is why Kansas is known for its tornadoes during spring because equal amounts of hot and cold air meet, creating these strong torrents.

I remember that in Intuitor's analysis of The Abyss, it said that flooding the world like the underwater monsters almost did at the end would require about 2,100 megatons of force. How many megatons can underwater volcanoes produce? Would it have to happen in specific areas of the world, or could a sufficient level of force anywhere do it? Related question: Can we do anything about supervolcanoes, and how long do you think we have before they erupt and kill us?

I really don't know an exact number at the top of my head. But I would estimate it's nowhere near the necessary 2,100 megaton force requirement.

The best way to prepare for a supervolcano is to bunker up. There are seismometers that are placed in Yellowstone that let geologists predict if it might erupt. Last I checked, in the next 1,000 years it won't likely erupt. What it would do would be blanketing most of the top soil for farmers with ash, making it poisonous for plants.