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Requirements for Speed of Light/Faster Than Light Speeds
Introduction
The speed levels for Speed of Light and Faster Than Light are the starting point for when physics essentially starts to be broken, as it is not possible for non-massless objects to reach the speed of light without producing infinite energy and it's not possible for objects to move faster than light as it already takes infinite energy to move at the speed of light. Of course, fiction has broken this rule many times with characters outright surpassing the speed of light:
The purpose of this article is to note the strict requirements we have placed for reaching such levels of speeds that are normally impossible within reality.
Establishment
To start off, as our Tiering System & Attack Potency system, base our standards off real life and thus assume a verse for the most part follows our real life laws of physics in order to give them statistics, we also follow that the verse follows relativity. As we allow gravity to exist, a concept directly connected to relativity and time. Thus with this baseline established, achieving speeds faster then the speed of light is impossible as that requires infinite energy, and faster then light speeds are impossible as the faster you travel through space, the slower you travel through time.
Time Dilation
In physics, an explanation for space travel that goes around traveling beyond the speed of light is experiencing time dilation. As explained above, the faster you travel through space, the slower you travel through time or to quote better:
| “ | "Spacetime is 4-dimensional, as Space (3D) and time (the fourth dimension) are not separate, but in fact a four-dimensional continuum (space-time). The faster you travel through space, the slower you travel through time.
Imagine a light clock (between two mirrors the light bounces up and down and the time it takes from one to the other is one tick). One is on earth, one is on a spaceship, and both clocks seem to be working normally. However, the person on earth sees the spaceship differently: the light is moving both up and down and to the side, uniform with the ship. So for the space traveler, light travels at 300,000,000 m/s but only has to travel up and down. To the Earthbound observer, light travels at 300,000,000 m/s, but must travel a longer, diagonal distance. Then, for the Earthbound observer, the spacecraft clock takes longer to “tick”. This effect is called time dilation. The faster you travel through space, the slower you travel through time. This is another way of saying you can never travel faster than the speed of light as the clock would stop altogether." |
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| ~ Time Dilation Article by Stem Followship |
Another explanation can be explained here: This article is where we got our information from.
Time dilation refers to the fact that clocks moving at close to the speed of light run slow. Consider two observers, each holding an identical clock. These clocks work using pulses of light. An emitter bounces light off a mirror, and the reflected pulse is picked up by a detector next to the emitter. Every time a pulse is detected, a new pulse is sent out. So, the clock measures time by counting the number of pulses received; the interval between pulses is the time it takes for a pulse to travel to the mirror and back.
If our two observers are stationary relative to each other, they measure the same time. If they are moving at constant velocity relative to each other, however, they measure different times. As an example, let's say one observer stays on the Earth, and the other goes off in a spaceship to a planet 9.5 light years away. If the spaceship travels at a speed of 0.95 c (95% of the speed of light), the observer on Earth measures a time of 10 years for the trip.
The person on the spaceship, however, measures a much shorter time for the trip. In fact, the time they measure is known as the proper time. The time interval being measured is the time between two events; first, when the spaceship leaves Earth, and second, when the spaceship arrives at the planet. The observer on the spaceship is present at both locations, so they measure the proper time. All observers moving relative to this observer measure a longer time, given by:
In this case we can use this equation to get the proper time, the time measured for the trip by the observer on the spaceship:
So, during the trip the observer on Earth ages 10 years. Anyone on the spaceship only ages 3.122 years.
It is very easy to get confused about who's measuring the proper time. Generally, it's the observer who's present at both the start and end who measures the proper time, and in this case that's the person on the spaceship.
Carrying on with our example of the spaceship traveling to a distant planet, let's think about what it means for measuring distance. The one thing that might puzzle you is this: everything is relative, so a person on the Earth sees the clock on the spaceship running slow. Similarly, the person on the Earth is moving at 0.95c relative to the observer on the spaceship, so the observer on the ship sees their own clock behaving perfectly and the clock on the Earth moving slow. So, if the clock on the spaceship is measuring time properly according to an observer moving with the clock, how can we account for the fact that the observer on the ship seems to cover a distance of 9.5 light years in 3.122 years, which would imply that they're traveling at a speed of 3.04c?
That absolutely can not be true. For one thing, one of the implications of relativity is that nothing can travel faster than c, the speed of light in vacuum. c is the ultimate speed limit in the universe. For another, two observers will always agree on their relative velocities. If the person on the Earth sees the spaceship moving at 0.95c, the observer on the spaceship agrees that the Earth is moving at 0.95c with respect to the spaceship (and because the other planet is not moving relative to the Earth), everyone's in agreement that the relative velocity between the spaceship and planet is 0.95c.
So, distance is velocity multiplied by time and we know the velocity and time measured by the observer on the spacecraft is 0.95c and 3.122 years. This implies that they measure a distance for the trip of 2.97 light-years, much smaller than the 9.5 light-year distance measured by the observer on the Earth.
This is in fact exactly what happens; a person who is moving measures a contracted length. In this case, the person on the Earth measures the proper length, because they are not moving relative to the far-off planet. The observer on the spaceship, however, is moving relative to the Earth-planet reference frame, so they measure a shorter distance for the distance from the Earth to the planet. The length measured by the moving observer is related to the proper length by the equation:
In this case we can solve for the length measured by the observer on the spaceship:
This agrees with what we calculated above, as it should.
One important thing to note about length contraction: the contraction is only measured along the direction parallel to the motion of the observer. No contraction is seen in directions perpendicular to the motion.
As shown, it is possible to calculate how much time actually passed within space, though a lot of factors are needed that fiction normally does not provide.
Faster Than Light
Faster-than-light (also FTL, superluminal or supercausal) travel and communication are the conjectural propagation of matter or information faster than the speed of light (c). The special theory of relativity implies that only particles with zero rest mass (i.e., photons) may travel at the speed of light, and that nothing may travel faster.
Particles whose speed exceeds that of light (tachyons) have been hypothesized, but their existence would violate causality and would imply time travel. The scientific consensus is that they do not exist. "Apparent" or "effective" FTL, on the other hand, depends on the hypothesis that unusually distorted regions of spacetime might permit matter to reach distant locations in less time than light could in normal ("undistorted") spacetime.
As of the 21st century, according to current scientific theories, matter is required to travel at slower-than-light (also STL or subluminal) speed with respect to the locally distorted spacetime region. Apparent FTL is not excluded by general relativity; however, any apparent FTL physical plausibility is currently speculative. Examples of apparent FTL proposals are the Alcubierre drive, Krasnikov tubes, traversable wormholes, and quantum tunneling. Mostly, FTL proposals find loopholes around the theory of relativity, such as by expanding or contracting space to make the object appear to be travelling greater than c.
As such being at these speeds would essentially make light completely frozen, and the event would not be seen by the observer to it has alredy passed, as an example:
Space Travel
As explained above, space travel granting Faster Than Light is not an allowed idea due to the existence of time dilation, but also with the existence of "apparent" or "effective" FTL which proposes an area of space-time is distorted to temporarily allow faster then light travel"Apparent" or "effective" FTL,[1][2][3][4].
Black Holes
The normal idea behind black holes are that one needs to be faster than light to escape them as even light itself can't escape them, though contextually there is a reason behind why light can't escape that comes from here:
| “ | Question:
Is the reason light cannot escape a black hole more due to the relative stop in time within the EH rather than the gravity slowing down the speed of light? The light could still be travelling at c but since v is a function of t, the relative t elapsed to an observer is always zero. Answer: Within the event horizon of a black hole space is curved to the point where all paths that light might take to exit the event horizon point back inside the event horizon. This is the reason why light cannot escape a black hole. Another way to look at it is that the escape velocity from the event horizon of a black hole is faster than the speed of light. Since nothing can travel faster than the speed of light, nothing escapes the event horizon of a black hole. |
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| ~ Why Can’t Light Escape a Black Hole? -- Cardin, May 24, 2021 |
The idea of requiring faster than light sped is moreso that one needs a way to escape said curved space, which normally is impossible in real life without moving at Faster Than Light speeds, though in fiction where some characters resist Space-Time Manipulation innately and can move in warped/distorted space-time areas, they would be able to escape a black hole even with a curved space. Thus Faster Than Light for black holes would only work if the verse directly notes one is moving faster than light to escape it. Another thing is a black hole's gravitational pull is this strong, and a gravitation pull is not necessarily speed.
Requirements to obtain Speed of Light
The requirements here are pretty standard:
- If a character obtains a form where they are massless or can obtain a pure form of light that they travel through.
- Examples: Light Suit (Metroid)
- If a character is explicitly stated to move at the speed of light.
- If a character is actually noted or stated to achieve infinite mass while running.
Requirements to obtain Faster Than Light
The requirements for Faster Than Light delve into some deeper territories. At least one of the following are required:
- Laser/Lightspeed Attack Dodging: Firstly the laser would need to meet our Light Dodging Feats requirements. is one dodges a laser or a lightspeed attack a couple of questions must be fulfilled and reconciled to grant Faster Than Light. As explained in the Faster Than Light portion of this article, light is would appear slow or frozen to one faster then the speed of light, even at 1c. Thus attacks that travel at light speed would never truly be a threat to a Faster Than Light character. So unless the laser dodge was casual, be noted as slow to the character/from the character, or visually have a slow effect while dodging. An example as shown here:
Another thing to take into account is reconciling a pretty important question for a feat like this, which is what is the reason the character in question is using a Speed of Light attack if the verse is meant to be full of Faster Than Light characters. The normal explanations around this are, there's characters in the series that are not Faster Than Light that it's normally used on, they underestimated the opponent they're facing, it's merely just a part of the gear, etcetera. Though it is important to answer this question as this could further show a verse not being Faster Than Light.
- Another thing for light/laser dodging would be needing to meeting one of these requirements:
- The verse has advanced physics/technology (contextually this means the character is using said technology to amplify their speed or reactions).
- Examples: Samus Aran (Metroid)
- The characters are already shown to not have much effects from time itself (contextually this means they are normally unaffected by abilities).
- Examples: Link (Legend of Zelda)
- If the characters are in worlds outside of standard physics or they themself have abilities or powers that exist outside of the laws of physics.
- Magic normally is fine since that is a concept that ignores the laws of physics.
- The verse has advanced physics/technology (contextually this means the character is using said technology to amplify their speed or reactions).
- Direct Statements: If a character is directly stated to be faster then light, then they would be fine to apply.
- Examples: Saiki Kusuo (Saiki Kusuo no Psi Nan)
- Moving in a timeless voids/Moving in realms where time is non-linear: In a timeless void, the value of "T" would be equivalent to 0, as the flow of time in this realm would be nonexistent. Traversing such a place would be impossible for characters with finite speeds. The idea of reaching Faster Than Light speeds, where time slows down to a dead stop where space and time essentially do not exist at the speed of light itself. Though in certain cases it can also be Speed of Light speeds if the verse specifies it. This would also apply to moving in a place where time is not linear.
- Examples: The Batter (OFF)
Answering Potential FAQs
Q: What's the reason for the excessive strictness on SoL and FTL speeds?
A: To explain simply, for the longest time we would see a lot of verses both in and out of this wiki get FTL speeds though the narrative and how irl physics portrays it doesn't work. This would also add in stuff like characters being listed as light speed or FTL for being able to barely dodge lasers or light speed attacks they can still be tagged by. As an example, Lapis Lazuli from Steven Universe traveled from Earth to Homeworld which is at the edge of the galaxy, however gems bodies are composed of light and thus due to this, they cannot keep up with things moving faster than the speed of light[5].
Q: For time dilation, what about the idea that two observers are within the scene and the timeframe of travel looks short for both?
A: For cases like this we switch to "apparent" FTL as in this case, there are just localized areas of space-time that allow one to surpass light speed. This would obviously not scale to ones statistics.
Q: What about if one already has FTL reactions, would flying through space be applicable for Faster Than Light then?
A: If one has FTL reactions, they would be given Speed of Light travel speed for traveling across space, as once one hits the speed of light, they occupy all spaces at once from their perspective and time is frozen.
Q: What if a series directly notes it doesn't follow relativity?
A: In very rare cases where a series is noted to not follow this, one would not be limited by rules of relativity. However other requirements, such as laser dodging would still apply, as even without relativity, one at FTL speeds should still view light as frozen.
Q: Let's say my character is 99.99% into Relativistic+ and their speed increases, can I say here that they are Speed of Light or Faster Than Light?
A: The general consensus and agreement regarding speed amplifications at Relativistic speeds is that it will always add an extra .9 to the 99.99% SoL as approaching light speed would require one to have infinite energy or become massless and having a speed amplification into this scale would need either requirement for them to reach light speed. Along with this, speed amplifications through a multiplier also would not apply, for the simple reason of it being clear the author did not have a specific speed value in mind when giving the character the feat, thus they would not notice if a multiplier would send a character into SoL or FTL values of speed or not.
References
- ↑ Gonzalez-Diaz P. F., 2000 "Warp drive space-time" Archived Link: [1], Physical Review D, Volume 62, Issue 4, Page 044005
- ↑ Loup F., Waite D., & Halerewicz E. Jr., 2001 "Reduced total energy requirements for a modified Alcubierre warp drive spacetime"
- ↑ Visser M., Bassett B., & Liberati S., 2000, "Superluminal censorship", Nuclear Physics B: Proceedings Supplements, Volume 88 Issue 1–3, Pages 267–270
- ↑ Visser M., Bassett B., & Liberati S., 1999 "Perturbative superluminal censorship and the null energy condition", AIP Conference Proceedings, Volume 493, Pages 301–305
- ↑ *sighs* I think in your attempt to fix our bodies, you may have accidentally shut off the calibration altogether. Our light-composed forms couldn't keep up with the ship moving faster than the speed of light.
