Why can't we go faster than light? Can't we technically do so?

[kerbiloid]

When two photons meet each other in the same direction, then photonic love happens.
Sometimes baby photons.

[Green Baron]

Let's just assume everybody tries as good as he/she can. I think we can afford the tolerance to help or ask back if necessary :-)

[YNM]

9 hours ago, WinkAllKerb'' said:

wave, flow,wind  ; same sometime = constant ; sometime = not constant ;;; change size and time scale

I can tell you that the fluid and wave mechanics people (and I'm) learn(ing) have no implications to/from/of "modern" physics, even less to quantum ones. Mechanics of fluids are still describeable "classically", unless it's intentionally unclassical (like, dunno, magnetic fluid or some other exotic things).

Edited October 11, 2017 by YNM

[WinkAllKerb'']

well earth G , known universe center G, waves size and light and resistance & absoulte relative known friction push/absorbance [scaleS^n]

 

Edited October 11, 2017 by WinkAllKerb''

[ModZero]

15 hours ago, Spricigo said:

I mean: if  is important enough to post, you want people to undertand it. Correct?

Why do you hate art?

[Spricigo]

1 hour ago, ModZero said:

16 hours ago, Spricigo said:

I mean: if  is important enough to post in a scientific discussion, you want people to undertand it. Correct?

Why do you hate art?

fixed?

[KSK]

20 hours ago, Spricigo said:

Accordingly to the scientific consensus* it never, never, ever happens. 

*scientific consensus is when all scientists would love to tell something is wrong (but didn't found a convincing way) and at same time everyone is ready call anyone that say it an idiot. 

Hang on - photons are bosons right? So there's no limit to how many of them can occupy the same quantum state? So I'm not sure what does happen when two photons having the exact same direction speed and characteristic meet each other, but I see no reason why it can't happen.

Unless I'm mangling what little quantum theory I remember. Which is quite possible.

[Spricigo]

1 hour ago, KSK said:

Hang on - photons are bosons right?

Right.   Thank you for the correction.

 

*sighs* That is what happens when one post at superluminal speed.

[Spricigo]

1 hour ago, KSK said:

 I'm not sure what does happen when two photons having the exact same direction speed and characteristic meet each other

They don't interact with themselves, so which Photon will 'carry on with its life as usual'. Anything else that would be there to be affected by one photon will be affected by two photons.

 

[PB666]

On 10/5/2017 at 7:59 PM, Grand Ship Builder said:

Why is there a "speed limit" in the universe? According to special relativity, nothing can move faster than light, but Newton's first law states that unless an external force affects it, an object's speed will always stay the same. So, if we find a large space of perfect vacuum, with no force affecting any part of it, and if we had enough fuel and thrust, we could technically go at the speed of light and faster since there would be no external force affecting us, there would be nothing to slow us down. 

 

Classical physics does not apply to matter as they approach the speed of light from the position of an observer. Einstein predicted and his predictions have been verified for particles outside of the quantum scale.

e = mc^2, as this translates, if you continue to increase speed e no longer = 1/2 m₀v^2 but mass begins to increases. The observed mass, length and aging undergo Lorenz transformations.

Secondarily, The reason that light travels at speed of light is that the default (straitline waveform propogation rate) speed of the observable universe is C, plank speed of 1. Its not that light travels at light speed, all non-massive particles (fields) travel at C. Perturbations are unidirectional (fractionalizing) in nature and generally attributed to the massive nature of particles. IOW you are granted a speed of C but complex interactions of waveforms slows you down. The most notorious are the fermions and bosons that give rise to massiveness. Briefly bosons of the higgs type create spacetime, that translates to dimensions of space and time. They also create stickyness of space that allow certain particles to have mass. Because energetic waveforms are trapped in atoms and not allowed to propogate in space e = mc^2 these particles also create mass. A single massive inert particle such as a helium can exist at the speed of comoving space at nearly zero thermal energy. As energy is applied in can generate radiation (infrared), orbital decay (emmission spectrum), directional change in motion, or non-spontaneous nuclear mutation.  Thus the application of energy is seldomly perfectly efficient.

Standard fuels are in the range of 100 kcal per mole. At their best they can produce ISP(sec) of 500, exhaust velocities of 5000 m/s. The best conventional space engine we have is ISP 475. ION drives provide ISP up to C/10 but at a tremendous cost of power. So much power to use even a 10,000 ISP ION drive at present would require a huge array of heat tolerant solar panels and fly-bys of mercury to generate the power to ION drives that would requires 1000 years at maximum solar input to reach 'C' (i.e. in the 0.1C to C range). The fission powered rocket only reachs 800 ISP and there are claims it could reach 4000 ISP, but engine is heavy and thrust to weight ratio is not good. This leaves the vaporous Fusion powered ION drives, conceivably possible to generate enough power to ION drive nuclear waste at an exhaust velocity of 0.5c again it would take at least 200 years to reach C. Again, such drives would have alot of waste heat an imperfect exhaust so even if one had 100 fuel to 1 fixed mass, you have a long way to go to reach C. The fuel for a fussion reactor is hydrogen, which is difficult to keep for 200 years.

Optimistically (very much so) 0.1c is going to be practical limit for biological space speeds. Microscopic devices can be remotely powered. Humanized craft will accelerate at 1 or less g for a year to Millenia and likewise slowdown.

 

[YNM]

8 hours ago, PB666 said:

Classical physics does not apply to matter as they approach the speed of light from the position of an observer. Einstein predicted and his predictions have been verified for particles outside of the quantum scale.

... Unless when it comes to the space itself.

 

The only way to have such high a relative velocity is to let spacetime takes it's course...

[Spricigo]

2 hours ago, YNM said:

... Unless when it comes to the space itself.

 

The only way to have such high a relative velocity is to let spacetime takes it's course...

That's not the rate of change in position something in space have. It's just the rate of change in how many space there is. Should we call it 'speed'?

 

[Green Baron]

If you refer to the expansion of space (of the universe) then no, it is nothing one can catch up with. Space doesn't expand into something and no matter how fast you go in any direction there is always a personal sphere around you at whose outer edge galaxies and clusters flee with lightspeed.

[wumpus]

On 10/11/2017 at 7:23 AM, YNM said:

I can tell you that the fluid and wave mechanics people (and I'm) learn(ing) have no implications to/from/of "modern" physics, even less to quantum ones. Mechanics of fluids are still describeable "classically", unless it's intentionally unclassical (like, dunno, magnetic fluid or some other exotic things).

Oddly enough, digital signal processing (basically anything computing a fourier* or related transform) will see effects rather similar to Hiesenburg's uncertainty principle.  I *think* that they are related primarily due to underlying math behind waves in general, but really don't have the math to tell.  Basically it all comes out under "windowing theory".

* image, audio, and video compression often use discrete cosine transforms, a related transform.  I also took an undergraduate class on DSP in the early 90s which could now be almost completely replaced with the phrase "just take a 1k FFT...".

[Vanamonde]

A post or two have been removed from this thread. Please stick to the topic, and refrain from complaining about each other's writing styles. 

[YNM]

4 hours ago, Spricigo said:

That's not the rate of change in position something in space have. It's just the rate of change in how many space there is. Should we call it 'speed'?

The expansion rate isn't exactly "speed", but your movement wrt some other thing is still speed no matter what's moving it.

If only there's a way to "see" them... !

3 hours ago, wumpus said:

Oddly enough, digital signal processing (basically anything computing a fourier* or related transform) will see effects rather similar to Hiesenburg's uncertainty principle.  I *think* that they are related primarily due to underlying math behind waves in general, but really don't have the math to tell.  Basically it all comes out under "windowing theory".

* image, audio, and video compression often use discrete cosine transforms, a related transform.  I also took an undergraduate class on DSP in the early 90s which could now be almost completely replaced with the phrase "just take a 1k FFT...".

Well I'm sure waves on water courses don't need them really badly ! 

[Spricigo]

39 minutes ago, YNM said:

The expansion rate isn't exactly "speed", but your movement wrt some other thing is still speed no matter what's moving it.

If only there's a way to "see" them... !

Which movement you talk about?

There's no movement

 

Also, the hypothetical 'thing' separated by those ever increasing distances cannot observe each other (as you hint) and don't interacte. That is 'as good' as non-existent. Like the dragon in Carl's garage.

 

Edited October 13, 2017 by Spricigo

[YNM]

4 hours ago, Spricigo said:

Which movement you talk about?

There's no movement

 

Also, the hypothetical 'thing' separated by those ever increasing distances cannot observe each other (as you hint) and don't interact. That is 'as good' as non-existent. Like the dragon in Carl's garage.

Yup, exactly my point.

There's still a movement. Just because you're being washed offshore by the waves from the beach doesn't mean you don't move wrt the beach.

 

Also, there's no way to tell what, where, and how are these things that's relatively faster than light to us.

So I think, anything that moves faster than light may as well doesn't exist (?)