Earlier quoted context omitted.
I don't think anybody thinks such a ship is possible with chemical rockets.
Just need Astrophage /s
Ha, got the Hail Mary ref.
Why can’t I go faster than the speed of light?
221–230 of 234 posts
Re: Why can’t I go faster than the speed of light?
#222Earlier quoted context omitted.
It's a fantasy as long as you are still living under the tyranny of the rocket equation.
I don't think anybody thinks such a ship is possible with chemical rockets.
It's worse than that. It's not possible with any type of rocket. If you are accelerating by pushing mass in an opposite direction then you'll never build a ship that can accelerate at 1G for years at a time.
Unless we invent a reactionless drive the idea of traveling between solar systems remains a pipe dream.
Re: Why can’t I go faster than the speed of light?
#223Earlier quoted context omitted.
And the reason for this, as we all know, is because the universe runs on distributed computers with no global state, where each computer simulates its own local physics and connects only to other nearby computers, and thus the so-called speed of light is simply the emergent rate that data may travel across the network.
No, has to be more subtle than that. The rate the simulators transmit data are irrelevant to our timeframe (since we’re a part of the computation). I believe it’s more like a centralized interpreter with decentralized (NP) evaluation strategies. The limit reflects the minumium size of a recursive expression.
I meant NTM*, that is to say, assuming many-world interpretation where the way your conscious experience of your life makes quantum measurements by (somehow) following the shorest accpeting computation of the NTM. Your life is thus meaningful as everything you experience from birth to death is literally the solution.
Consciousness (at least in this world) can perchance then be understood as the artifact of a feedback loop constructed by a (meta-circular) interpreter that converts the topologies of molecules into qualia, which then makes adjustment to the reflective tower (with physiological-changes-in-brain&body as correspondence).
Time perception then is the same consequence that follows relativity ie a direct result of this speed limit that reflects the minumium size of a recursive expression (but concerning only the viscosity and turbulence of neurotransmitters in relative to eletric signals?)
Re: Why can’t I go faster than the speed of light?
#224Earlier quoted context omitted.
Bad news CMB shifts into infrared, visible, uv, xray and then hard gamma.
since we are talking insane speeds and energies required to reach them why not just say you are in a bigger ship with more radiation shielding a dozen or so meters of water in the hull and a layer of lead a foot thick aught to stop most of it
FWIW, the Project Rho page I linked to also gives the derivation of the relativistic rocket equation. When I plugged in numbers, assuming an exhaust velocity of the speed of light (ie. impossibly high), I get a mass fraction of about 2,000,000 to reach top speed. Then another 2,000,000 to slow down.
Assuming the fully loaded RV weighs 5 tons, this means at max velocity the rest of the ship weighs 10 megatons, which is 10M cubic meters of water, or a cube 200m on each side.
That sounds like plenty of material, right?
The same Project Rho page links to https://arxiv.org/ftp/physics/papers/0610/0610030.pdf which calculates that at the relatively slow 0.995c "the penetration depth of protons of this energy will be ~40 m in water and ~10 m in titanium".
For 99.99999999993978% c, even 10M cubic meters isn't going to be enough.
Re: Why can’t I go faster than the speed of light?
#225Earlier quoted context omitted.
If we could somehow make it into a donut planet we could presumably sit in the middle of it experiencing no acceleration. Would the time dilation effects still occur then?
I don't think so. As I understand it, gravity and acceleration are equivalent, if you aren't experiencing any acceleration then time dilation won't occur. (Assuming we are not traveling near the speed of light)
One of the more mindbending things to wrap your head around is that gravity isn't a force (i.e doesn't not cause acceleration in the F=Ma sense.). You're simply on a path through spacetime warped by gravity.
Think about it: when you are in free fall you feel 0 acceleration. You appear to be accelerating relative to the ground-- but you're actually motionless in an "inertial reference frame". (Similar to how the astronauts on the ISS don't "feel" acceleration despite accelerating rapidly relative to the earth.)
The "force" of gravity is often modeled as "gravity pulling you down" and the ground "pushing you back up". This works mathematically, but isn't quite logically consistent.
In reality, on the ground you're in a region of warped spacetime, so you feel constant upward acceleration despite not actually accelerating. (Thinking of this another way, standing on earth feels identical to being in a far away spaceship accelerating at 9.8 m/s².)
This is also why time "speeds up" near more massive objects. (Separate from "acceleration".)
We're so used to gravity this it doesn't seem weird. But when you consider the fact free-fall is when you're not accelerating... well pondering that from many angles is what ultimately led Einstein to his model of relativity.
(This is me trying to condense what could be a 10 minute explanation into a few sentences, so apologies if it's not particularly clear.)
Re: Why can’t I go faster than the speed of light?
#226Nobody postulated that the speed of light is constant because it was obvious: light just like every other wave has a constant speed in the medium though which it propagates. The fact that nothing can go faster is a consequence of the Lorentz transformation, so nothing had to be postulated. The important thing that Einstein recognized is that the Lorentz transformations apply for all physical phenomena and not only th…
This is very interesting. Does it mean we can observe the constant speed phenomenon for other waves e.g waves in water or sound waves or waves in a spring or a string?
That will be very comprehensible
Re: Why can’t I go faster than the speed of light?
#227A bit all over the place, the author assumes "It is even less well-known that the rule “nothing moves faster than the speed of light” is a consequence of the laws of electricity and magnetism" but at the same time "This is also a well-known property of electricity and magnetism" and then drops some equations. Most people for whom this property of electricity and magnetism is well known, also know that the speed limit…
People can disagree with your assessment, but it’s pretty sad that you write the only comment in this thread that actually engaged with the content of the linked article, and it’s downvoted.
Re: Why can’t I go faster than the speed of light?
#228Earlier quoted context omitted.
>Convention to me would mean something that has been accepted just because it’s always been done that way and people didn’t really bother to question why. You're wrong. The Thermodynamic laws are sort of axiomatic, meaning you really can't explain why energy is conserved. It's just experimentally shown to be maybe true, but no one knows why energy is conserved or has actually proved it to be true. It is totally "conv…
Thank you for writing this and introducing the word axiomatic. I was using the word convention as something that is defined and unquestionable. It's an assumption we base all of our physics equation on. Axiomatic might capture the meaning better. This means, and I assume, we can also base all of our equations on say "energy is not conserved and always increase by 1 Joule", though the physics equations might be much m…
>This means, and I assume, we can also base all of our equations on say "energy is not conserved and always increase by 1 Joule", though the physics equations might be much more complex.
We can but this won't match with observations. We assume energy is conserved only because our current observations show that it has been conserved thus far.
Referring to the OP article, he's basically writing that the c being the absolute speed limit is not axiomatic. It's not something we just assume to be true. It is a theorem derived from the assumption (aka axiom) that the universe cannot produce inconsistent events.
Re: Why can’t I go faster than the speed of light?
#229Earlier quoted context omitted.
If we could somehow make it into a donut planet we could presumably sit in the middle of it experiencing no acceleration. Would the time dilation effects still occur then?
I don't think so. As I understand it, gravity and acceleration are equivalent, if you aren't experiencing any acceleration then time dilation won't occur. (Assuming we are not traveling near the speed of light)
Then what about just orbiting around it? It would just need to be big enough to not cause strong tidal forces.
Re: Why can’t I go faster than the speed of light?
#230Q1. Does the future already exist? I realize this might be purely philosophical, but if I leave Earth, and fly through space near c kph, and return home a few hours later to find everyone aged 50 years... are they the "same" people, or are they a future-instance of the people left? To clarify, theoretically I could leave earth, and return home in exactly 1 hour (from my ref frame), and basically make people whatever…
I suggest stop giving time a privileged meaning, and think of it as just one of four dimensions. John Wheeler starts his book on Special Relativity[1] by talking about surveying. You and I survey a building (plot of land, whatever) separately because we want to check each other's work. At then end we look at our data and disagree on every single coordinate except the origin. Ah, you're a crappy surveyor, I conclude.…
Wheeler also postulated that all electrons had indistinguishable properties because they were the same electron (moving back and forward through time). So in some sense Wheeler is treating time like a stack. (cant remember if Feynman convinced him otherwise)