Star Trek Question

[Lorpius Prime]

So you're in your big starship Enterprise, cruising along at Warp 5, and you run into a photon. What happens?

I mean, you can outrun light, so do all the little rays youc catch up with get caught against the hull, and are dragged along for the ride? Wouldn't this produce a blinding flash of light whenever you stopped?

Help.

[Big Brother]

Lorpius said:

So you're in your big starship Enterprise, cruising along at Warp 5, and you run into a photon. What happens?

I mean, you can outrun light, so do all the little rays youc catch up with get caught against the hull, and are dragged along for the ride? Wouldn't this produce a blinding flash of light whenever you stopped?

Help.

In Star Trek terms, this is exactly what the "navigational deflector fields" are supposed to avoid. Magnetic and gravitational fields sweep the space ahead of the hurtling starship and brush aside things like micrometeorites, dust and gas particles, stray atoms of hydrogen, and charged particles like electrons and protons from the solar wind. These fields are mentioned in one episode as being able to stop laser beam weapons on a spacecraft from a less advanced alien race, so presumably they also sweep aside photons (apparently other than those that hit the sensors so they can see where they are going).

In reality, this is one of the many problems with high-speed space travel. Real-life spacecraft so far mainly rely on dumb luck and a tiny amount of structural reinforcement on the forward end of the ship. The space shuttle has survived several minor collisions, one with a stray paint flake that left a small crater in the windsceen in front of the pilot's chair. When you're orbiting at 40,000 miles an hour, even paint flakes are dangerous. Had that one been a tiny bit heavier or moving a tiny bit faster, the big window would have shattered and the flight deck would have lost pressure catastrophically, probably killing all or most of the crew.

Real life spacecraft so far don't go fast enough to worry about photons much. Nor will future ones, since even if you're going at 99.5% of the speed of light, a light beam from, say, your own headlights will still appear (to you) to be zooming out ahead of you at 100% of the speed of light faster than you. ALL observers always measure the speed of light as the same, it's the only real constant in the universe. Photons always hit you with the same energy regardless of whether you're heading towards them or speeding away from them.

What future relativistic spacecraft WILL have to worry about will be particle radiaton. A stray proton or electron from the solar wind, when bumped into at half the speed of light, suddenly goes from a harmless particle to deadly ionizing radiation. Protons and electrons at least have an electromagnetic charge, and probably will be able to be brushed aside by magnetic fields not entirely unlike the navigational deflectors on Star Trek. Even non-ionized atoms such as stray hydrogen and helium gas molecules can be ionized by a powerful laser beam and thus made susceptible to magnetic shielding. Uncharged particles like neutrons will be a real headache to get rid of, however, as will macroscopic dust particles too heavy to brush aside with magnetic fields or vaporize with a laser, yet too small to see with enough warning time to change course. So most proposed designs for realistic spacecraft capable of a significant percentage of light speed (Project Orion and Project Daedalus, for instance) include large armored shields at the front to absorb such impacts. Beyond a few percent of light speed, however, the energy of impact with anything of non-trivial mass gets too big to absorb with mere inches or feet of steel, and will require some as-yet-unknown technology to overcome.

[Lorpius Prime]

Wow, thanks.

Though I didn't get a real response. The Star Trek ships go faster than the speed of light, and yet they are able to see through their front viewscreens just fine...wouldn't there be a problem with photons piling up? Or you catching up with your own headlights? (Yeah, I know nothing about physics, I only pretend)

[Big Brother]

Lorpius said:

Wow, thanks.

As my sister is the Canon Mistress, I am the Technobabble God, and I live to serve.

Lorpius said:

Though I didn't get a real response. The Star Trek ships go faster than the speed of light, and yet they are able to see through their front viewscreens just fine...wouldn't there be a problem with photons piling up? Or you catching up with your own headlights? (Yeah, I know nothing about physics, I only pretend)

There are a couple of problems here.

First off, in real physics, nothing can go faster than light. I finally read a good explanation for WHY this is so (beyond the increasing mass factor), but it's too long to go into here (and I'm still not sure if I really get it). Star Trek has given several explanations for how their ships go faster than light, none of them entirely consisten with the observed special effects footage.

Some sources say they enter a hyperspace-like higher dimension (and thus would not encounter photons and such from our dimension at all). That is more Star Wars than Star Trek, though.

Some say they warp space into a bubble, and then move the bubble along with them. This also would mean not encountering photons, since photons from outside the bubble would be deflected aside by the warp. Photons from inside the bubble would not be any different from photons near a stationary starship, since it's the bubble not the ship that is moving.

Some sources say the engines grab the fabric of space and twist it, then sort of twirl it like giant paddles to push through space. This is utter bull manure, of course, but oddly most consistent with the visual effects (but not the dialogue, which mostly supports the bubble theory). This seems to be the method most likely to encounter the "piling up photons" problem.

Which, of course, is no problem at all.

Dialogue in the show clearly states that the navigational deflector fields sweep aside all harmful radiation (presumably including photons) in the path of the ship. So that's one explanation for how that problem is avoided.

So how do they see? Very well. But mostly not by looking out windows, they see with sensors. Even the Main Viewscreen on the bridge is really a sensor display, not a window. The pics of ships and moons could very well be computer simulations based on some sort of exotic non-electromagnetic sensor system we can only dream of today. Maybe it's the Fairy Cake extrapolation device from HHGTTG, heh heh!

But what would happen if they COULD overtake a photon? What happens when you run into a photon normally? Either it bounces off or gets absorbed. Photons hitting the ship's bow would be no different. Either they'd bounce off (to the side or to immediately be hit again and eventually absorbed, as no surface is 100% reflective) or get absorbed (thus heating the skin of the ship, and yet another obstacle to building real-life high-speed starships).

But as I said before, in real-life physics, you can't go faster than the speed of light, and thus can't catch up with your own headlights.

]

[Mlle Bienvenu]

Big said:

As my sister is the Canon Mistress, I am the Technobabble God, and I live to serve.



There are a couple of problems here.

First off, in real physics, nothing can go faster than light. I finally read a good explanation for WHY this is so (beyond the increasing mass factor), but it's too long to go into here (and I'm still not sure if I really get it).

Can you give me a point me on that info? I'd be interested in reading about that reason that isn't the increasing mass factor Thanks ^_^

[Big Brother]

The explanation I referred to starts on page 47 of the paperback edition of The Elegant Universe by Brian Greene.

[Big Brother]

Okay, here's a crappy attempt at explaining this idea...

Say you took a fancy sports car out for a test drive on a wide, flat stretch of dry lake bed out in Utah. This is a special car, which can ONLY drive at its top speed. For the first few test drives of the afternoon, you travel along the top edge of the diagram here along the line AC. And I just realized I drew this backwards, so imagine that somehow West is towards the right edge of the map. My slight dyslexia strikes again...



Each test run, the car travels at the same top speed and takes the same amount of time to go from the start line to the finish line. However, as the afternoon fades to evening and the sun starts to go down, the low-in-the-sky sun starts to shine right in the driver's eyes, so you start crossing the test track at a slight angle, so that the sun isn't directly in your eyes as you drive just North (down on this backwards diagram) of West. The car is still going at the same top speed, yet is traveling a longer, diagonal path (line AE on the diagram) to get from the start line to the finish line. And so the time measured to go from the start line to the finish line is slightly longer.

This is akin to what objects moving in 4-dimensional spacetime go through. In the diagram, the 3 spatial dimensions are simplified to one (up-down) and the left-right axis measures time.

Just as the fancy race car in the example above has only one possible speed, physical objects have only one possible speed, the speed of light. Objects "at rest" are actually hurtling through the temporal dimension at the speed of light, a speed of "time travel" we would measure in human units as one second per second. Since the speed of light is the only allowable speed, to travel "diagonally" through spacetime (and thus move some distance along the space axis) instead of a straight line along the time axis (and be an object at rest), one must travel less distance along the time axis than an object with the same net vector (the speed of light) that does not waste some of its total motion traveling along the space axis.

Assume for the sake of argument (since my art skills suck big time) that the line AD in that drawing is the same length as the line AC. The line AC represents the path through spacetime of an object at rest, traveling at the speed of light into the future along the time axis but not moving at all along the space axis. The line AD represents the path through spacetime of an object that IS moving in space. Since it must move along the space axis over to the value of a point I should have labeled "F" but instead is where I put "Fig. 1", but its total net vector can only add up to the same length as the line AC, its partial vector along the time axis will only be as long as the line AB, which means that someone taking that path will measure only "B" seconds as having passed, instead of "C" seconds.

This is all much better explained in the book,with better diagrams, but I've already got a headache trying to sort it out well enough to explain it.

EDIT: Changed location of image host, so the pic should show up now for those that couldn't see it before.

[Lorpius Prime]

That's awesome, makes sense of the whole "time is relative" statement, which I pretty much just had to accept without explanation before.

Thanks Mart.

[Mlle Bienvenu]

Hmmm...sound's interesting, can't see the picture though so it's a bit difficult to grasp... must reread this when I'm awake :-) Thanks for posting it up, BB ;D

[Big Brother]

Okay, changed the host for that image so it should show up now.

[Mlle Bienvenu]

Thanks :-) The diagram is very helpful :-)