If you just extend time dilation beyond zero (I.e. negative time) then speed faster than light is possible. The constraint described in the article will still be maintained. Also, notice that negative time would be the perception of external observer.
Why can’t I go faster than the speed of light?
121–130 of 234 posts
Re: Why can’t I go faster than the speed of light?
#122Earlier quoted context omitted.
> > If I travelled at one percent of speed of light, same distance, i suppose 100 years would elapse for me, how much would elapse on earth? > I don't know how to do the math, but a very, very long time would have passed on earth. Eh, at .01c, not so much: https://www.omnicalculator.com/physics/time-dilation?c=USD&v... (=100.005y, not even two days extra)
Yeah, all interesting things only begin at roughly 0.5c and go crazy at 0.9c. Google images on “lorentz factor” to get the quick idea. https://www.google.ru/search?q=lorentz+factor&tbm=isch
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Re: Why can’t I go faster than the speed of light?
#123Earlier quoted context omitted.
At 1G constant acceleration (both speeding up and slowing down) you can make it on a short vacation to the Andromeda galaxy and back in a lifetime (or 5 million years from the perspective or Earth).
It looks like about 57 years. Assuming constant acceleration to the 1/2-way point, flip, deceleration, and using http://www.projectrho.com/public_html/rocket/slowerlight3.ph... : Time elapsed (in starship's frame of reference, "Proper time") T = (c/a) * ArcCosh[a*d/(c^2) + 1] (given acceleration and distance) year = 365.25*24*3600; c = 3E8; a=9.8; d=1.25*1_000_000*(c * year) from math import acosh T = (c/a) * acosh(a…
Bad news CMB shifts into infrared, visible, uv, xray and then hard gamma.
Re: Why can’t I go faster than the speed of light?
#124Earlier quoted context omitted.
It is instantaneous from the perspective of the object’s internal clocks . Traveling at the speed of light results in infinite time dilation. Which means that from the perspective of an outside observer, no time at all is passing inside the spaceship.
What happens to fields (magnetic, gravitational, electrostatic, etc) in that situation? E.g. can a photon 'feel' the surfaces it would ultimately interact with? One way I like to think of this is the term 'sun-kissed'. From the perspective of the photon, the sun is actually giving you a kiss on a summer day.
'feel' the surfaces it would ultimately interact with
I would like to see the map of the universe at different potential speeds (or thrusts). E.g. you choose a point in space nearby the sun. At thrust zero you only see hot sun everywhere, because there you go anyway. But at greater thrusts the sun turns into a circle and you start to see sections of the “sky” where you could land, given the thrust is constant. Some areas would be still black because of blackholes, orbits and event horizon. I always wanted that simulation but never found it. It would be much more interesting than just looking around via reversed photons flying into your eyes.
Re: Why can’t I go faster than the speed of light?
#125Earlier quoted context omitted.
To put it another way, time travel machines are very much theoretically possible, and in fact are “only” an engineering problem (an extremely hard one, however). But, only forward travel is allowed: time travel machine could take you as far forward as its engineering would allow it, but there is no going back.
They are only theoretically possible if you allow for negative mass and energy--not an engineering problem so much as a "need to find exotic matter" Basically people ran the EFE "backwards" to see what matter distribution makes the wanted curvature. You get either negative mass-energy or the bubble doesn't travel ftl iirc.
No, for forward time travel you don’t need any sort of exotic matter. You just need a really fast rocket.
Re: Why can’t I go faster than the speed of light?
#126I think a lot of people assume that this means you couldn't go more than a few (~100) light-years in your lifetime... But this is not actually correct. Counter-intuitively you can theorically go any number of light-years (essentially) in your lifetime, as long as you are able to approach the speed of light because when you do so the distance is dilated and hence you're covering far more ground within your reference f…
I know this is true, but I never got my head around this, maybe someone can help. So if a photon is emitted from the sun, it's passing earth immediately? Then why does sunlight need 7 or 8 minutes to get to earth? And let's say, i travel one light-year at the speed of light, that should be instantaneous, right? The odometer would show 1 light-year, my watch would should 0 seconds and some decimals. How much would I h…
because light doesn't experience time, and the closer you get to the speed of light, the less time you experience. So what OP didn't say was that, while YOU can travel many lightyears in your lifetime, everyone you know will long be dead.
Re: Why can’t I go faster than the speed of light?
#127If anyone wants to play with a speed of light, there [still] is a fun web game called “velocity raptor”.
Re: Why can’t I go faster than the speed of light?
#128Earlier quoted context omitted.
If you were watching their lives out the window of your spaceship you’d see them in fast forward vv. they’d see you in slow motion. Everything is relative. The main ”paradox” found by experimention is that the speed of light is a constant, regardless of your velocity. The only way this could be true, if you do a thought experiment, is if time was dialating for you. As for the physical and mathematical “why is this ha…
> If you were watching their lives out the window of your spaceship you’d see them in fast forward vv. they’d see you in slow motion. Everything is relative. Both observers, looking at one another, would see the other moving near c. Neither would know who was ‘actually’ moving. Yet, you assume there would not be a symmetry in their respective views of the other’s passage of time. Explain why. In simpler terms, a twin…
I asked this in physics when I first heard the twin experiment. The answer comes from more complicated relativity based on acceleration and depends entirely on which reference frame you meet in. If you travel back to earth you age slower, if the twin catches up to you they aged slower....
It's not intuitive but time actually warps and there is no true concept of "simultaneous" in a special relativity world.
Re: Why can’t I go faster than the speed of light?
#129Earlier quoted context omitted.
I know this is true, but I never got my head around this, maybe someone can help. So if a photon is emitted from the sun, it's passing earth immediately? Then why does sunlight need 7 or 8 minutes to get to earth? And let's say, i travel one light-year at the speed of light, that should be instantaneous, right? The odometer would show 1 light-year, my watch would should 0 seconds and some decimals. How much would I h…
> So if a photon is emitted from the sun, it's passing earth immediately? Then why does sunlight need 7 or 8 minutes to get to earth? From the photon's perspective, it passes earth immediately. From our perspective, it takes 7 or 8 minutes. > And let's say, i travel one light-year at the speed of light, that should be instantaneous, right? The odometer would show 1 light-year, my watch would should 0 seconds and some…
just curious... does "time" have a "speed" ?
Is travelling at the speed of light, actually travelling a a fraction of the speed of time?
Re: Why can’t I go faster than the speed of light?
#130Earlier quoted context omitted.
> So if a photon is emitted from the sun, it's passing earth immediately? Then why does sunlight need 7 or 8 minutes to get to earth? From the photon's perspective, it passes earth immediately. From our perspective, it takes 7 or 8 minutes. > And let's say, i travel one light-year at the speed of light, that should be instantaneous, right? The odometer would show 1 light-year, my watch would should 0 seconds and some…
just curious... does "time" have a "speed" ? Is travelling at the speed of light, actually travelling a a fraction of the speed of time?
Yes, one second per second.