Solar Panel at the Speed of Light

Haai Hendrik.

Couple of clarifications needed.

Do you mean 'solar powered' as in converting radiation into some other form of energy and then propelling the spaceship with it? Solar power can also be used as a solar sail, where the 'solar wind' is used as propulsion, but it is not very efficient, especially going generally towards the Sun.

If you mean the solar power is just used for generating electricity, while there is another form of propulsion used, the 0.8c is perhaps possible, but reaching c, hardly!

Please clarify in order to prevent wild speculation.

Jorrie

Hi Jorrie

Actually only interested in the output of the solar panel - for any appropriate use.

for example: if you had a roof light in the ship and uses a solar powered calculator fixed to the console directly underneath the light. Will the calculator receive enough light if the ship goes at light speed?

Might I try this one...

Solar cells (at least with modern technology) seem to be most efficient toward the near infrared. If traveling close to the speed of light, your light source (i.e.; the Sun) is blue shifted, then much of its energy is going to become unusable to you.

Let's assume you're speaking of silicon or gallium-arsenide solar panels to produce electricity that, say, powers some form of propulsion system (a super-duper ion drive of futuristic design). Not that the composition or form of your panels, your drive, nor your ship will be all that useful once you've achieved your objectives.

Now, the faster you approach the Sun, the greater the blueshift of the light striking your sun-facing panels. And as you recede from the Sun, the greater the redshift.

If, as you say, you've looped around the Sun and are now receding from it at nearly speed of light (getting your ship to the speed of light is a bit difficult with merely a finite amount of energy at your disposal, so I'm hedging a bit here), the light striking your Sun-facing panels (striking them at the speed of light, no less) will have a frequency very close to zero. Solar panels of any stripe don't respond well to DC daylight.

On the flip side, let's say you've nearly achieved light-speed and are approaching a nearby star. Proxima Centauri, for example. The light from that star (and every other star in your trajectory's line of sight) will be blue-shifted to a wavelength of nearly zero. Solar panels don't respond well to that kind of light either. Nor do people. You will find yourself (and your panels) bathed in an inferno of photons that would make the hottest cosmic rays pale by comparison. Sunscreen will not help you here, but a couple parsecs' thickness of depleted uranium might - if it lasts.

And did I mention that as you accelerate to such velocities over a short distance (doing so entirely within the neighborhood of the Sun is "a short distance" on these scales), you might just be fried to a crisp not from the Sun, but from of the enormous apparent temperature of the Universe's blackbody radiation? Not to mention all those nasty virtual particles that just popped out of nowhere once you kicked in the afterburners. Blame Unruh for that. Like, there's always some friggin' physicist lurking in the wings gleefully waiting to rain on someone's parade.

Honestly, wouldn't you rather be sipping a nice margarita at the beach? I've heard Vanuatu ain't bad.

Not to mention that if you sped toward the Sun at even the slightest % of the speed of light, you'd go shooting past the Sun and out into deep space. That is, of course if your trajectory wasn't targeted on the center of the Sun.

^poof!!!

The slightest % will send me shooting past the Sun? Well that explains it! Just yesterday I set out for a walk to the corner store and found myself deep in the Oort Cloud. Next time I'll wear my parka.

Watch out for those bricks!!!

Do you mind? I'm eating dinner! (Sorry, Thread. Private joke.)

Hi Hendrik.

On top of what "vermin" and "europium" correctly stated, when you pass 'underneath' the Sun at near light-speed you have no or little radial speed relative to it, so there is no red- or blue-shift due the Doppler variety.

For that very brief period, your solar powered calculator should work nearly as advertised, provided you orientate the ship so that the calculator gets enough of the highly aberrated sunlight on it through the window.

Jorrie

Okay, Jorrie: how brief, ship's time? And he'd better not blink!

Hi -e, how brief? It depends.

With the engine that Hendrik's got on board, I suppose he can just fly around and around the Sun in a powered orbit and keep on using his calculator...

Jorrie

Jorrie, in response to the orginal query (Solar Panel at the Speed of Light), does any discussion really matter, as it would essentially be impossible to accelerate a material object to close to "c". As a material body accelerates beyond significant fraction of "c", the mass would become "much greater", requiring more and more propulsion, ad infinitum. Or are we just talking "what if...". Thanks.

Hi Cardio07, yep, it's basically just a 'what if...'.

I've written a reply to the 'Light Speed Motor Scooter' challenge thread in which I tried to illustrate that a 100% efficient rocket would use up all of its mass-energy to achieve a speed of light with practically nothing left...

Sorry, I haven't look up the reply#, but it's somewhere on the first page of that long thread.

Jorrie

The question suggests to this innocent--the possible non-validity of the question notwithstanding--that: if "speed" is a valid, cosmic construct and, if the speed of mass conversion to energy and infinite dimension (of the solar converter and transporter) was approached (even asymptotically speaking, of course) and, if light itself--or photon--is a real entity occupying non-unbounded (albeit possibly infinite) space...

then all light itself--or anything which converted to E = mc2 state--must itself exist in total surrounding "darkness." Corollary: light must be bounded by darkness and be undetectable--even to an "intelligent photon." Hope this makes some sense. Jorrie? Anyone?

There is flaw in the problem, based on a misunderstanding of the mechanism of catapaulting from one space object towards another

Catapault acceleration from a planet towards another only works because as the space ship enters the gravitational pull of the catapulting planet, the the ship gains the velocity of the planet. Thus the ship leaves the catapaulting planet with a higher velocity towards the target planet than it would have had it not been inthe vicinity of the catapaulting planet. The catapaulted planet also suffers deceleration by gravitational pull of the catapaulting planet as it moves away, but the gain it made from the catapault is not lost

With the ship nearing the sun, the sun is the centre of the solar system and no planet has a particularly high radial component of velocity. So the ship accelerates towards the sun and orbits behind it and as it moves away it is decelerated by the sun. There was no catapault gain in velocity to the target panet, and the high speeds spoken of in the problem will not be achieved.

That is true, but the speed at which you approach the Sun is far too high for it mass to hold you in orbit. You escape the Sun's gravity and just continue on an adjusted path into deep space.

You flea-infested rat. I was just beginning to enjoy this bit of fiction. Heard there's a good Free-Energy forum just down the street. Think I'll join it. I'm sick of reality.

Catapulting around planets, as was done with the Voyager and other deep-space missions, increases the momentum of the the spacecraft whilst decreasing the momentum of the planet by the same amount. As planets tend to have a bit more mass, their change in velocity is imperceptible. And it works the same way in the Sun's case, as well, because the Sun's orbit (wiggly and erratic though it be) around the galaxy's center of mass is not so discernible as an 'orbit' as such. Besides, the Sun is dragging all these other planets around with it, so even if you could measure the change in velocity, it wouldn't be with respect to the local system, but with the galaxy as a whole. Mass is mass. Doesn't matter whether it's glowing or not.

Besides, I saw 'em do it in Star Trek.

I rather slip into another dimension for a shorter trip around the block with a little String Theory bring up my rear.

I tried that, and did it work? I'm a frayed knot.