also, that's a bummer, @chimera I more or less mentioned it so that cops would penalize the amateurs or the thrill seekers, fine them, and get them off the road. then again, there's not much to just say that you are going to x town, not storm watching. its still fucking infuriating having to deal with them though.
like you said, I'm more than happy to mentor someone, or teach them the proper method and safety procedures. I'd like for wildcats to get their come uppence because they are dumbing down and diluting the field.
Still, you get what you pay for, and I've seen *tons* of shit pics, vids and reports. It is vindicating for me however, when a client tries someone else and they come back to us a month later because the they can't produce a report anywhere close to what we do.
Cosmos is not as fun when you already know this stuff
Is this how geologists and zoologists feel about Planet Earth?
You think that is bad? Try being a meteorologist and/or chaser and watch Twister or Into The Storm.
That's basically the same for any professional watching their own field on screen.
Storms / sharks / IT systems / Ancient tombs / banks / World War 2 decrypting machines do not work that way!
My pet peeve is movies about the game industry. Where investors are wowed into throwing money at you by a pitch that consists of "imagine a game... with great graphics... that's really fun!" And some guy working in his garage in his spare time can single handedly make Grand Theft Auto 6. And yet every game ever made sounds like Atari 2600 Pac-Man.
or any footage ever of people playing games via the hyperactive molestation of the controller method
Lets not sell our solar system short just yet; Earth has a ridiculously large sized moon so our night sky is going to be a lot more exciting that most, plus you'd have to go a very long way to find another planet which is just the right distance for the sun and moon appear almost the same size.
We could very well live in the only place in the galaxy where you're able to see a solar eclipse.
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TraceGNU Terry Pratchett; GNU Gus; GNU Carrie Fisher; GNU Adam WeRegistered Userregular
Charles Townes, the Nobel Prize-winning physicist credited with the invention of the laser and its predecessor — the maser — died in Oakland, Calif., on Tuesday.
Townes’ health had been rapidly deteriorating and he died on the way to the hospital, according to the University of California Berkeley, where he had taught physics since 1967.
Townes, who was 99, jointly won the 1964 Nobel Prize in Physics for his contribution to the field of lasers, sharing it with two Russian scientists.
Born in Greenville, S.C., in 1915, Townes studied at Duke University before completing his PhD at Caltech in 1939. A stint at Bell Labs was followed by a faculty position at Columbia University, where he taught before moving to MIT in 1961 and finally to Berkeley six years later.
“Charlie Townes had an enormous impact on physics and society in general,” said Steven Boggs, professor and chair of the UC Berkeley Department of Physics. “His overwhelming dedication to science and personal commitment to remaining active in research was inspirational to all of us.”
Lets not sell our solar system short just yet; Earth has a ridiculously large sized moon so our night sky is going to be a lot more exciting that most, plus you'd have to go a very long way to find another planet which is just the right distance for the sun and moon appear almost the same size.
We could very well live in the only place in the galaxy where you're able to see a solar eclipse.
Well, a total eclipse anyway.
But yeah, the moon is pretty rad in binoculars or a properly filtered telescope.
Universe, why do all the cool things have to be so far away? We're just stuck with a single boring moon in a sea of white dots.
Usually because they'd kill us if they were in our solar system.
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ChimeraMonster girl with a snek tail and five eyesBad puns, that's how eye roll. Registered Userregular
Hey there nerds, geeks, and closet weather weanies! Want to learn what truly goes into my forecasts I use to chase tornadoes? Well mow is your chance to learn from one of the field of meteorology's leading experts, Rich Thompson! Rich is the lead forecaster for NOAA's Storm Prediction Center which is the orginization that issues tornado and severe t-storm watches for the United States. They also do much more than that, but the watches they issue are the primary products they issue that most members of the public will be failure with.
This will be a very in depth crash course and in the end will aford even a novice weather enthusiasts a sound understanding of how to forecast for tornadoes and offer materials and knowledge that one would normally have to pay a decent amount to receive in a collage course. This isn't just some spotter training or a tv weatherman workshop but a very rare opportunity to get a real leas on from one of the most vetted and best in the business of severe weather forecasting! Who better to learn from than NOAA's/The National Weather Service/SPC's number one forecaster of severe weather?
Rich is hosting a weekly forecasting class and workshop starting this coming tusday night. Even if you are a beginer I highly recommend sitting in on the live webcasts if you are even the least bit curious. If you are in the Norman, OK or OKC area you can go to the National Water Center on the OU Campus and attend the sessions live!
Bellow you will find more info on each session as well as the time and date for each weekly class. If you plan on watching or attending please let me know by messaging me or repling to this post in this thread.
We are extremely pleased to announce that we have partnered with the Storm Prediction Center's Lead Forecaster Rich Thompson to offer a unique series of workshops detailing the meteorology of tornado forecasting! If you want to hear from a longstanding professional about the process of making the forecasts for severe weather, this is for you. Anyone is welcome to attend these free workshops, either in person or online; see the attached flier for more details!
Here's the current schedule:
February 3rd – Sounding analysis and synoptic meteorology (lifted parcels, Q-G theory, etc.)
February 10th – Severe storm ingredients (low-level moisture and lapse rates)
February 17th – Severe storm ingredients (vertical shear and lift)
March 3rd – Supercell and tornado conceptual models (plus composite parameters)
March 10th – Tornado patterns (synoptic and mesoscale)
March 24th – Convective mode forecasting (squall lines vs. discrete cells)
April 7th – Tornado parameter climatology (spatial and temporal distributions of CAPE and shear)
April 14th – Numerical models and statistical techniques (convective schemes and post processing)
That's pretty cool! I don't know if I can watch them all live, so hopefully they will have an archive available afterwards.
From what I've heard they may! A friend of mine is managing the lice stream for it so I will ask him. Because you will most likely be able to I tract and ask questions during the live stream I highly recommend you attend as many of those as you can and only rely on the archives for if you can't make a session.
I likely will be there in person on some nights that I am in town.
Great..... now I am stuck watching all of his music videos in a binge of his work. Oh well I guess it will help prepare me for his concert here in OKC thats coming up.
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Captain Marcusnow arrives the hour of actionRegistered Userregular
Cryptographic systems often rely on the secrecy of cryptographic keys given to users. Many schemes, however, cannot resist coercion attacks where the user is forcibly asked by an attacker to reveal the key. These attacks, known as rubber hose cryptanalysis, are often the easiest way to defeat cryptography. We present a defense against coercion attacks using the concept of implicit learning from cognitive psychology. Implicit learning refers to learning of patterns without any conscious knowledge of the learned pattern. We use a carefully crafted computer game to plant a secret password in the participant’s brain without the participant having any conscious knowledge of the trained password. While the planted secret can be used for authentication, the participant cannot be coerced into revealing it since he or she has no conscious knowledge of it. We performed a number of user studies using Amazon’s Mechanical Turk to verify that participants can successfully re-authenticate over time and that they are unable to reconstruct or even recognize short fragments of the planted secret.
Oh that is cool
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ElJeffeNot actually a mod.Roaming the streets, waving his gun around.Moderator, ClubPAmod
What does it say about me that my first thought upon seeing this was "First Outer Inner Last"?
I submitted an entry to Lego Ideas, and if 10,000 people support me, it'll be turned into an actual Lego set!If you'd like to see and support my submission, follow this link.
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jungleroomxIt's never too many graves, it's always not enough shovelsRegistered Userregular
I am not ok with all the awesome stuff being far away.
Or let me summarize: someone invent the Frame Shift Drive already.
Yeah, that's not going to happen. The Alcuberrie drive is only possible if particles with negative mass can exist.
I thought this wasn't the case? Wasn't that the point of NASA's warp field mechanics experiment? That the principle behind it should be able to be demonstrated with existing technology on a microscopic scale at least.
I am not ok with all the awesome stuff being far away.
Or let me summarize: someone invent the Frame Shift Drive already.
Yeah, that's not going to happen. The Alcuberrie drive is only possible if particles with negative mass can exist.
I thought this wasn't the case? Wasn't that the point of NASA's warp field mechanics experiment? That the principle behind it should be able to be demonstrated with existing technology on a microscopic scale at least.
By my very simplistic understanding, I think the sole reason for testing it was they thought they might have found a way to essentially BS the universe with math so you could avoid needing a negative mass that actually exists.
AbsoluteZeroThe new film by Quentin KoopantinoRegistered Userregular
This has been on my brain lately...
Relativity does not allow for particles to accelerate past the speed of light, but it does allow for particles that are always faster than light. The arrow of time for such a particle would be reversed relative to our own, so essentially it would be traveling backwards through time from our point of view.
Lets say that such a particle does exist. How would we ever observe it? My thinking is, if T for us is advancing, and T for this particle is receding, we will only occupy the same T for an instant, meaning to observe the particle we would have to know not only where it will be, but when it will be, which would be impossible to predict.
Relativity does not allow for particles to accelerate past the speed of light, but it does allow for particles that are always faster than light. The arrow of time for such a particle would be reversed relative to our own, so essentially it would be traveling backwards through time from our point of view.
Lets say that such a particle does exist. How would we ever observe it? My thinking is, if T for us is advancing, and T for this particle is receding, we will only occupy the same T for an instant, meaning to observe the particle we would have to know not only where it will be, but when it will be, which would be impossible to predict.
Am I coming at this completely wrong?
Relativity does not allow for particles that travel faster than the speed of light. Feynman did propose interpreting anti-particles as particles traveling backwards in time. They can be observed like any other particle. The laws of physics are microscopically invariant under time reversal, so there is no special difficulty in observing them - as you advance into their past, they advance into yours.
Presumably at (our) T and T+1 the particle would simply be separated by a distance > c, it's also possible they may be moving "backwards" too - but since they would also be non-causal we would never be able to create them so that wouldn't matter
Just_Bri_ThanksSeething with ragefrom a handbasket.Registered User, ClubPAregular
Besides, even if we say a particle traveling backwards in time there would be little to distinguish it from a particle traveling forwards in time. IT's not like it has a front or a back end which would allow us to determine that it was traveling in reverse.
...and when you are done with that; take a folding
chair to Creation and then suplex the Void.
I recall reading a while back about the theoretical time traveling particles and the idea was that such a particle would appear during a particle collision, but un-like other components of an atom which would fly away from an atom after a collision this would fly in to the point of collision seemingly from nowhere as if it has traveled through all of space just so that it could be there when the atoms collide. You know, like a time traveler would to kill the equivalent of atom Hitler.
Or something like that.
DanHibiki on
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AbsoluteZeroThe new film by Quentin KoopantinoRegistered Userregular
To be clear, I'm not concerned with whether or not FTL particles exist. Rather, I'm wondering how we could possibly observe them. I'm having a hard time making sense of the idea that a particle traveling backwards through time could even interact with our universe at all.
@DanHibiki That would be incredible, and a hell of a thing to see. Sure would create causality problems if we could summon these beasties at will!
To be clear, I'm not concerned with whether or not FTL particles exist. Rather, I'm wondering how we could possibly observe them. I'm having a hard time making sense of the idea that a particle traveling backwards through time could even interact with our universe at all.
@DanHibiki That would be incredible, and a hell of a thing to see. Sure would create causality problems if we could summon these beasties at will!
Why do you think a particle traveling faster than light would move backwards in time?
The fact that the 'best' proposals to have these particles are to either involve an imaginary mass and/or breaking Lorentz Invariance, and even then they need to be totally undetectable unless they break causality puts this pretty far into 'crazy ideas that are not 100% ruled out'
Besides, even if we say a particle traveling backwards in time there would be little to distinguish it from a particle traveling forwards in time. IT's not like it has a front or a back end which would allow us to determine that it was traveling in reverse.
Ehh...
Inverse particle decay.
Which should be a relativistic phenomenon, give that normal particle decay, that of cosmic rays for instance is observably dilated.
To be clear, I'm not concerned with whether or not FTL particles exist. Rather, I'm wondering how we could possibly observe them. I'm having a hard time making sense of the idea that a particle traveling backwards through time could even interact with our universe at all.
@DanHibiki That would be incredible, and a hell of a thing to see. Sure would create causality problems if we could summon these beasties at will!
Why do you think a particle traveling faster than light would move backwards in time?
Because an observable FTL particle could be used to violate causality, where an event happens before the event that caused it. That is, from the event's observer's point of view, it must have traveled into the past to do that.
This is a good explanation of how you can violate causality with FTL signals: http://www.theculture.org/rich/sharpblue/archives/000089.html
My only problem with this page, is their Figure 1 really should have had Event Q at the same coordinates as it is in Figure 2 so it would illustrate better how a Lorentz Transformation can change Event Q from being in Event P's relative future, to being in Event P's relative past. That is, if you take Figure 1 and 2's Event P's coordinates (space, time) as (0,0) with up being positive numbers and right being positive numbers, they should have placed Event Q at (-2,+0.5) in Figure 1. That matches Event Q's blue coordinates in Figure 2. Then you could easily see in Figure 2 that Event Q's blue coordinates in Event P's white reference frame have changed from (-2,+0.5) to (-1.9,-0.25) with the Lorentz Transformation, the time coordinate going from +0.5 to -0.25 illustrates that Event Q has moved from Event P's relative future into Event P's relative past.
As Sander mentioned, FTL particles either allow causality violation which would be rather problematic, or they are non-observable / non-interacting which would make their existance moot.
SiliconStew on
Just remember that half the people you meet are below average intelligence.
To be clear, I'm not concerned with whether or not FTL particles exist. Rather, I'm wondering how we could possibly observe them. I'm having a hard time making sense of the idea that a particle traveling backwards through time could even interact with our universe at all.
@DanHibiki That would be incredible, and a hell of a thing to see. Sure would create causality problems if we could summon these beasties at will!
Why do you think a particle traveling faster than light would move backwards in time?
Because an observable FTL particle could be used to violate causality, where an event happens before the event that caused it. That is, from the event's observer's point of view, it must have traveled into the past to do that.
This is a good explanation of how you can violate causality with FTL signals: http://www.theculture.org/rich/sharpblue/archives/000089.html
My only problem with this page, is their Figure 1 really should have had Event Q at the same coordinates as it is in Figure 2 so it would illustrate better how a Lorentz Transformation can change Event Q from being in Event P's relative future, to being in Event P's relative past. That is, if you take Figure 1 and 2's Event P's coordinates (space, time) as (0,0) with up being positive numbers and right being positive numbers, they should have placed Event Q at (-2,+0.5) in Figure 1. That matches Event Q's blue coordinates in Figure 2. Then you could easily see in Figure 2 that Event Q's blue coordinates in Event P's white reference frame have changed from (-2,+0.5) to (-1.9,-0.25) with the Lorentz Transformation, the time coordinate going from +0.5 to -0.25 illustrates that Event Q has moved from Event P's relative future into Event P's relative past.
As Sander mentioned, FTL particles either allow causality violation which would be rather problematic, or they are non-observable / non-interacting which would make their existance moot.
I'm not really sure I buy this graph. I mean, I know relativity changes perception of time, but it seems to be saying that simply by opening a hole in space to a moving person you'd be opening a hole to the past?
Like, if I open a hole in space on January 1st and hand a letter off to a guy traveling at 0.5 lightspeed, he'll get it on Jan 1st. But then if he opens a hole in space and passes it to someone else moving at 0.5 LS, it's going to be December 31st for that person? Or it doesn't become Dec 31st until they open a hole and give it back to me?
Cryptographic systems often rely on the secrecy of cryptographic keys given to users. Many schemes, however, cannot resist coercion attacks where the user is forcibly asked by an attacker to reveal the key. These attacks, known as rubber hose cryptanalysis, are often the easiest way to defeat cryptography. We present a defense against coercion attacks using the concept of implicit learning from cognitive psychology. Implicit learning refers to learning of patterns without any conscious knowledge of the learned pattern. We use a carefully crafted computer game to plant a secret password in the participant’s brain without the participant having any conscious knowledge of the trained password. While the planted secret can be used for authentication, the participant cannot be coerced into revealing it since he or she has no conscious knowledge of it. We performed a number of user studies using Amazon’s Mechanical Turk to verify that participants can successfully re-authenticate over time and that they are unable to reconstruct or even recognize short fragments of the planted secret.
Oh that is cool
Ha!
I cannot believe we didn't do that earlier.
That's like... that's really simple and really easy and makes a lot of sense. There are hundreds of cognitive science experiments that result in people knowing something without consciously being aware that they know it.
To be clear, I'm not concerned with whether or not FTL particles exist. Rather, I'm wondering how we could possibly observe them. I'm having a hard time making sense of the idea that a particle traveling backwards through time could even interact with our universe at all.
@DanHibiki That would be incredible, and a hell of a thing to see. Sure would create causality problems if we could summon these beasties at will!
Why do you think a particle traveling faster than light would move backwards in time?
Because an observable FTL particle could be used to violate causality, where an event happens before the event that caused it. That is, from the event's observer's point of view, it must have traveled into the past to do that.
This is a good explanation of how you can violate causality with FTL signals: http://www.theculture.org/rich/sharpblue/archives/000089.html
My only problem with this page, is their Figure 1 really should have had Event Q at the same coordinates as it is in Figure 2 so it would illustrate better how a Lorentz Transformation can change Event Q from being in Event P's relative future, to being in Event P's relative past. That is, if you take Figure 1 and 2's Event P's coordinates (space, time) as (0,0) with up being positive numbers and right being positive numbers, they should have placed Event Q at (-2,+0.5) in Figure 1. That matches Event Q's blue coordinates in Figure 2. Then you could easily see in Figure 2 that Event Q's blue coordinates in Event P's white reference frame have changed from (-2,+0.5) to (-1.9,-0.25) with the Lorentz Transformation, the time coordinate going from +0.5 to -0.25 illustrates that Event Q has moved from Event P's relative future into Event P's relative past.
As Sander mentioned, FTL particles either allow causality violation which would be rather problematic, or they are non-observable / non-interacting which would make their existance moot.
I'm not really sure I buy this graph. I mean, I know relativity changes perception of time, but it seems to be saying that simply by opening a hole in space to a moving person you'd be opening a hole to the past?
Like, if I open a hole in space on January 1st and hand a letter off to a guy traveling at 0.5 lightspeed, he'll get it on Jan 1st. But then if he opens a hole in space and passes it to someone else moving at 0.5 LS, it's going to be December 31st for that person? Or it doesn't become Dec 31st until they open a hole and give it back to me?
No, "opening a hole" would be the same as an instantaneous signal. Such a signal travels along the space axis of the diagram, but being instantaneous, does not move along the time axis. A signal that traveled at any speed less than infinity would move forwards along the time axis. But a signal between any pair of observers cannot move backwards along the time axis. That means you cannot directly open a hole to the past. That's why the example uses two pairs of observers.
A and B are not moving relative to each other. They are separated by a distance, but can pass messages between themselves instantaneously. This does not violate causality because a message sent A->B at T=0 and then sent back B->A some small time later T+1, it will arrive at A at T+1, that is, some time in A's future. Even if it was sent back immediately it would at best arrive at A at T=0, not in A's past. Also, because A and B are separated in space, even though A sent information to B FTL, B cannot physically influence A's timeline based on that knowledge except at some point in A's future because they cannot physically move outside their green future light cones.
C and D are also not moving relative to each other, but are separated by a distance between them and they can talk instantaneously between themselves just as A & B can. However, C & D are moving relative to A & B. The idea is you send a message A->B at time T=0, then as C flies past B, B hands the message to C. (This doesn't necessarily have to happen the instant B receives the message, it just makes the diagram easier to understand.) So, now C has the message at T=0. That message is then sent C->D at time T=0. Remember C & D are stationary relative to each other so T=0 for C is still T=0 for D. So now D has the message at T=0 relative to himself. But now, because of the Lorentz Transformation from the relative motion and because we've arranged to put B & C at the same point in space-time when they fly by each other, D is now in A's past light cone, such that T(D)=0 equals T(A)=-1. Now if D sends the message to A, A will have received their own message before they sent it. Also D doesn't have to send the message to A FTL. D is inside A's past light cone which means he can send it via conventional means and A will observe that as happening sometime in A's past.
From A & B's point of view, C sent the message into the past to D.
Now switch perspectives from what A & B observed, to what C & D observed. C received a message at time T=0. D gets the message from C at time T=0. D forwards that message to A and A receives it some time in D's future T+1. A then sends a message to B which B receives and then hands it to C at time T=0
From C & D's point of view, A sent the message into the past to B.
The paradox in this is that A & B's interactions don't violate causality, B & C's interactions don't violate causality, C & D's interactions don't violate causality, D & A's interactions don't violate causality, and yet taken together, the message was received before it was sent which does violate causality.
SiliconStew on
Just remember that half the people you meet are below average intelligence.
To be clear, I'm not concerned with whether or not FTL particles exist. Rather, I'm wondering how we could possibly observe them. I'm having a hard time making sense of the idea that a particle traveling backwards through time could even interact with our universe at all.
@DanHibiki That would be incredible, and a hell of a thing to see. Sure would create causality problems if we could summon these beasties at will!
Why do you think a particle traveling faster than light would move backwards in time?
Because an observable FTL particle could be used to violate causality, where an event happens before the event that caused it. That is, from the event's observer's point of view, it must have traveled into the past to do that.
This is a good explanation of how you can violate causality with FTL signals: http://www.theculture.org/rich/sharpblue/archives/000089.html
My only problem with this page, is their Figure 1 really should have had Event Q at the same coordinates as it is in Figure 2 so it would illustrate better how a Lorentz Transformation can change Event Q from being in Event P's relative future, to being in Event P's relative past. That is, if you take Figure 1 and 2's Event P's coordinates (space, time) as (0,0) with up being positive numbers and right being positive numbers, they should have placed Event Q at (-2,+0.5) in Figure 1. That matches Event Q's blue coordinates in Figure 2. Then you could easily see in Figure 2 that Event Q's blue coordinates in Event P's white reference frame have changed from (-2,+0.5) to (-1.9,-0.25) with the Lorentz Transformation, the time coordinate going from +0.5 to -0.25 illustrates that Event Q has moved from Event P's relative future into Event P's relative past.
As Sander mentioned, FTL particles either allow causality violation which would be rather problematic, or they are non-observable / non-interacting which would make their existance moot.
I'm not really sure I buy this graph. I mean, I know relativity changes perception of time, but it seems to be saying that simply by opening a hole in space to a moving person you'd be opening a hole to the past?
Like, if I open a hole in space on January 1st and hand a letter off to a guy traveling at 0.5 lightspeed, he'll get it on Jan 1st. But then if he opens a hole in space and passes it to someone else moving at 0.5 LS, it's going to be December 31st for that person? Or it doesn't become Dec 31st until they open a hole and give it back to me?
A and B are not moving relative to each other. They are separated by a distance, but can pass messages between themselves instantaneously. This does not violate causality because a message sent A->B at T=0 and then sent back B->A some small time later T+1, it will arrive at A at T+1, that is, some time in A's future. Also, because A and B are separated in space, even though A sent information to B FTL, B cannot physically influence A's timeline based on that knowledge except at some point in A's future because they cannot physically move outside their green future light cones.
C and D are also not moving relative to each other, but are separated by a distance between them and they can talk instantaneously between themselves just as A & B can. However, C & D are moving relative to A & B. The idea is you send a message A->B at time T=0, then as C flies past B, B hands the message to C. (This doesn't necessarily have to happen the instant B receives the message, it just makes the diagram easier to understand.) So, now C has the message at T=0. That message is then sent C->D at time T=0. Remember C & D are stationary relative to each other so T=0 for C is still T=0 for D. So now D has the message at T=0 relative to himself. But now, because of the Lorentz Transformation and because we've arranged to put B & C at the same point in space-time when they fly by each other, D is now in A's past light cone, such that T(D)=0 equals T(A)=-1. Now if D sends the message to A, A will have received their own message before they sent it. Also D doesn't have to send the message to A FTL. D is inside A's past light cone which means he can send it via conventional means and A will observe that as happening sometime in A's past.
From A & B's point of view, C sent the message into the past to D.
Now switch perspectives from what A & B observed, to what C & D observed. C received a message at time T=0. D gets the message from C at time T=0. D forwards that message to A and A receives it some time in D's future T+1. A then sends a message to B which B receives and then hands it to C at time T=0
From C & D's point of view, A sent the message into the past to B.
The paradox in this is that A & B's interactions don't violate causality, B & C's interactions don't violate causality, C & D's interactions don't violate causality, D & A's interactions don't violate causality, and yet taken together, the message was received before it was sent which does violate causality.
What's the limit on how far back a message can go? It would seem that there should be a hard cap you cannot get information beyond in this setup (sort of a "can't travel back in time to before the invention of the time machine" type thing).
There isn't absolute ruling out of FTL, actually. A relative velocity faster than c is forbidden, which is different from "no FTL". There are theoretical ways to cheat that haven't been proven impossible.
And frankly... humanity is just plain fucked if there's no way to cheat.
What's the limit on how far back a message can go? It would seem that there should be a hard cap you cannot get information beyond in this setup (sort of a "can't travel back in time to before the invention of the time machine" type thing).
There is no limit relatively speaking. If you assume you can communicate instantaneously at any distance, you just keep increasing the spacial distance between A&B and between C&D and the time differential between D and A will keep increasing. But yes, you can't change D's or B's or C's past. Or to flip it around, you can only influence A's future but you could do so at a point an arbitrarily long time from now.
SiliconStew on
Just remember that half the people you meet are below average intelligence.
There isn't absolute ruling out of FTL, actually. A relative velocity faster than c is forbidden, which is different from "no FTL". There are theoretical ways to cheat that haven't been proven impossible.
And frankly... humanity is just plain fucked if there's no way to cheat.
There's also a lot of questions about some of the possible time machines that spring up: i.e. while you can show at a high level they could exist, actually trying to construct one (mathematically) usually shows that various forces conspire to stop them from forming.
So it's entirely possible that FTL could be possible, but would be in such a way that you simply couldn't engage in causality violating actions while performing - i.e. you can go faster then light, but can't influence an observer in their past light-cone because your engine becomes non-FTL when you get near them.
To be clear, I'm not concerned with whether or not FTL particles exist. Rather, I'm wondering how we could possibly observe them. I'm having a hard time making sense of the idea that a particle traveling backwards through time could even interact with our universe at all.
@DanHibiki That would be incredible, and a hell of a thing to see. Sure would create causality problems if we could summon these beasties at will!
Why do you think a particle traveling faster than light would move backwards in time?
Because an observable FTL particle could be used to violate causality, where an event happens before the event that caused it. That is, from the event's observer's point of view, it must have traveled into the past to do that.
This is a good explanation of how you can violate causality with FTL signals: http://www.theculture.org/rich/sharpblue/archives/000089.html
My only problem with this page, is their Figure 1 really should have had Event Q at the same coordinates as it is in Figure 2 so it would illustrate better how a Lorentz Transformation can change Event Q from being in Event P's relative future, to being in Event P's relative past. That is, if you take Figure 1 and 2's Event P's coordinates (space, time) as (0,0) with up being positive numbers and right being positive numbers, they should have placed Event Q at (-2,+0.5) in Figure 1. That matches Event Q's blue coordinates in Figure 2. Then you could easily see in Figure 2 that Event Q's blue coordinates in Event P's white reference frame have changed from (-2,+0.5) to (-1.9,-0.25) with the Lorentz Transformation, the time coordinate going from +0.5 to -0.25 illustrates that Event Q has moved from Event P's relative future into Event P's relative past.
As Sander mentioned, FTL particles either allow causality violation which would be rather problematic, or they are non-observable / non-interacting which would make their existance moot.
There is no Lorentz transformation that will cause a particle to move FTL. The page uses the special case of instantaneous transmission because a finite FTL speed makes the whole framework of special relativity gibberish. Not just causality-violating, but mathematically incoherent.
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ChimeraMonster girl with a snek tail and five eyesBad puns, that's how eye roll. Registered Userregular
You all are such nerds......
....and your discussion is making my science about clouds seem less amazing. :C
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Or let me summarize: someone invent the Frame Shift Drive already.
like you said, I'm more than happy to mentor someone, or teach them the proper method and safety procedures. I'd like for wildcats to get their come uppence because they are dumbing down and diluting the field.
Still, you get what you pay for, and I've seen *tons* of shit pics, vids and reports. It is vindicating for me however, when a client tries someone else and they come back to us a month later because the they can't produce a report anywhere close to what we do.
good luck man.
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Like these rubes, for example:
We could very well live in the only place in the galaxy where you're able to see a solar eclipse.
Yeah, that's not going to happen. The Alcuberrie drive is only possible if particles with negative mass can exist.
Well, a total eclipse anyway.
But yeah, the moon is pretty rad in binoculars or a properly filtered telescope.
Usually because they'd kill us if they were in our solar system.
This will be a very in depth crash course and in the end will aford even a novice weather enthusiasts a sound understanding of how to forecast for tornadoes and offer materials and knowledge that one would normally have to pay a decent amount to receive in a collage course. This isn't just some spotter training or a tv weatherman workshop but a very rare opportunity to get a real leas on from one of the most vetted and best in the business of severe weather forecasting! Who better to learn from than NOAA's/The National Weather Service/SPC's number one forecaster of severe weather?
Rich is hosting a weekly forecasting class and workshop starting this coming tusday night. Even if you are a beginer I highly recommend sitting in on the live webcasts if you are even the least bit curious. If you are in the Norman, OK or OKC area you can go to the National Water Center on the OU Campus and attend the sessions live!
Bellow you will find more info on each session as well as the time and date for each weekly class. If you plan on watching or attending please let me know by messaging me or repling to this post in this thread.
From what I've heard they may! A friend of mine is managing the lice stream for it so I will ask him. Because you will most likely be able to I tract and ask questions during the live stream I highly recommend you attend as many of those as you can and only rely on the archives for if you can't make a session.
I likely will be there in person on some nights that I am in town.
Neuroscience Meets Cryptography: Designing Crypto Primitives Secure Against Rubber Hose Attacks[/quote]
Great..... now I am stuck watching all of his music videos in a binge of his work. Oh well I guess it will help prepare me for his concert here in OKC thats coming up.
Oh that is cool
What does it say about me that my first thought upon seeing this was "First Outer Inner Last"?
I thought this wasn't the case? Wasn't that the point of NASA's warp field mechanics experiment? That the principle behind it should be able to be demonstrated with existing technology on a microscopic scale at least.
By my very simplistic understanding, I think the sole reason for testing it was they thought they might have found a way to essentially BS the universe with math so you could avoid needing a negative mass that actually exists.
Relativity does not allow for particles to accelerate past the speed of light, but it does allow for particles that are always faster than light. The arrow of time for such a particle would be reversed relative to our own, so essentially it would be traveling backwards through time from our point of view.
Lets say that such a particle does exist. How would we ever observe it? My thinking is, if T for us is advancing, and T for this particle is receding, we will only occupy the same T for an instant, meaning to observe the particle we would have to know not only where it will be, but when it will be, which would be impossible to predict.
Am I coming at this completely wrong?
Relativity does not allow for particles that travel faster than the speed of light. Feynman did propose interpreting anti-particles as particles traveling backwards in time. They can be observed like any other particle. The laws of physics are microscopically invariant under time reversal, so there is no special difficulty in observing them - as you advance into their past, they advance into yours.
chair to Creation and then suplex the Void.
Or something like that.
@DanHibiki That would be incredible, and a hell of a thing to see. Sure would create causality problems if we could summon these beasties at will!
Why do you think a particle traveling faster than light would move backwards in time?
The fact that the 'best' proposals to have these particles are to either involve an imaginary mass and/or breaking Lorentz Invariance, and even then they need to be totally undetectable unless they break causality puts this pretty far into 'crazy ideas that are not 100% ruled out'
Ehh...
Inverse particle decay.
Which should be a relativistic phenomenon, give that normal particle decay, that of cosmic rays for instance is observably dilated.
Because an observable FTL particle could be used to violate causality, where an event happens before the event that caused it. That is, from the event's observer's point of view, it must have traveled into the past to do that.
This is a good explanation of how you can violate causality with FTL signals: http://www.theculture.org/rich/sharpblue/archives/000089.html
My only problem with this page, is their Figure 1 really should have had Event Q at the same coordinates as it is in Figure 2 so it would illustrate better how a Lorentz Transformation can change Event Q from being in Event P's relative future, to being in Event P's relative past. That is, if you take Figure 1 and 2's Event P's coordinates (space, time) as (0,0) with up being positive numbers and right being positive numbers, they should have placed Event Q at (-2,+0.5) in Figure 1. That matches Event Q's blue coordinates in Figure 2. Then you could easily see in Figure 2 that Event Q's blue coordinates in Event P's white reference frame have changed from (-2,+0.5) to (-1.9,-0.25) with the Lorentz Transformation, the time coordinate going from +0.5 to -0.25 illustrates that Event Q has moved from Event P's relative future into Event P's relative past.
As Sander mentioned, FTL particles either allow causality violation which would be rather problematic, or they are non-observable / non-interacting which would make their existance moot.
I'm not really sure I buy this graph. I mean, I know relativity changes perception of time, but it seems to be saying that simply by opening a hole in space to a moving person you'd be opening a hole to the past?
Like, if I open a hole in space on January 1st and hand a letter off to a guy traveling at 0.5 lightspeed, he'll get it on Jan 1st. But then if he opens a hole in space and passes it to someone else moving at 0.5 LS, it's going to be December 31st for that person? Or it doesn't become Dec 31st until they open a hole and give it back to me?
Ha!
I cannot believe we didn't do that earlier.
That's like... that's really simple and really easy and makes a lot of sense. There are hundreds of cognitive science experiments that result in people knowing something without consciously being aware that they know it.
No, "opening a hole" would be the same as an instantaneous signal. Such a signal travels along the space axis of the diagram, but being instantaneous, does not move along the time axis. A signal that traveled at any speed less than infinity would move forwards along the time axis. But a signal between any pair of observers cannot move backwards along the time axis. That means you cannot directly open a hole to the past. That's why the example uses two pairs of observers.
A and B are not moving relative to each other. They are separated by a distance, but can pass messages between themselves instantaneously. This does not violate causality because a message sent A->B at T=0 and then sent back B->A some small time later T+1, it will arrive at A at T+1, that is, some time in A's future. Even if it was sent back immediately it would at best arrive at A at T=0, not in A's past. Also, because A and B are separated in space, even though A sent information to B FTL, B cannot physically influence A's timeline based on that knowledge except at some point in A's future because they cannot physically move outside their green future light cones.
C and D are also not moving relative to each other, but are separated by a distance between them and they can talk instantaneously between themselves just as A & B can. However, C & D are moving relative to A & B. The idea is you send a message A->B at time T=0, then as C flies past B, B hands the message to C. (This doesn't necessarily have to happen the instant B receives the message, it just makes the diagram easier to understand.) So, now C has the message at T=0. That message is then sent C->D at time T=0. Remember C & D are stationary relative to each other so T=0 for C is still T=0 for D. So now D has the message at T=0 relative to himself. But now, because of the Lorentz Transformation from the relative motion and because we've arranged to put B & C at the same point in space-time when they fly by each other, D is now in A's past light cone, such that T(D)=0 equals T(A)=-1. Now if D sends the message to A, A will have received their own message before they sent it. Also D doesn't have to send the message to A FTL. D is inside A's past light cone which means he can send it via conventional means and A will observe that as happening sometime in A's past.
From A & B's point of view, C sent the message into the past to D.
Now switch perspectives from what A & B observed, to what C & D observed. C received a message at time T=0. D gets the message from C at time T=0. D forwards that message to A and A receives it some time in D's future T+1. A then sends a message to B which B receives and then hands it to C at time T=0
From C & D's point of view, A sent the message into the past to B.
The paradox in this is that A & B's interactions don't violate causality, B & C's interactions don't violate causality, C & D's interactions don't violate causality, D & A's interactions don't violate causality, and yet taken together, the message was received before it was sent which does violate causality.
What's the limit on how far back a message can go? It would seem that there should be a hard cap you cannot get information beyond in this setup (sort of a "can't travel back in time to before the invention of the time machine" type thing).
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There isn't absolute ruling out of FTL, actually. A relative velocity faster than c is forbidden, which is different from "no FTL". There are theoretical ways to cheat that haven't been proven impossible.
And frankly... humanity is just plain fucked if there's no way to cheat.
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There is no limit relatively speaking. If you assume you can communicate instantaneously at any distance, you just keep increasing the spacial distance between A&B and between C&D and the time differential between D and A will keep increasing. But yes, you can't change D's or B's or C's past. Or to flip it around, you can only influence A's future but you could do so at a point an arbitrarily long time from now.
There's also a lot of questions about some of the possible time machines that spring up: i.e. while you can show at a high level they could exist, actually trying to construct one (mathematically) usually shows that various forces conspire to stop them from forming.
So it's entirely possible that FTL could be possible, but would be in such a way that you simply couldn't engage in causality violating actions while performing - i.e. you can go faster then light, but can't influence an observer in their past light-cone because your engine becomes non-FTL when you get near them.
There is no Lorentz transformation that will cause a particle to move FTL. The page uses the special case of instantaneous transmission because a finite FTL speed makes the whole framework of special relativity gibberish. Not just causality-violating, but mathematically incoherent.
....and your discussion is making my science about clouds seem less amazing. :C