Physics/Astronomy Questions for Sci-Fi Story

General Questions
#1

iI’m writing a science fiction short story, and while I have most of the scien ce figured out, I need to fine-tune some of it to sound more plausible:

  1. I need a fairly distant star in which to place a fairly small system, preferably in a semi-well known constellation.
  2. How is the speed of light affected by quantum mechanics and/or the four basic forces of the universe? (Gravity, electromagnetism, strong nuclear, weak nuclear)
  3. How would a localized alteration of the strengths of these forces influence the objects involved? For example, could a weakened strong nuclear force make nuclei more prone to fission, thus producing more radiation?

Thanks for your help!

#2

If your looking for something similar to our Sun, then 18 Scorpii is for you.

If not, use the search engine and type other parameters your looking for in your star and see what pops up.

I’ll leave #2 and #3 for the heavyweights (like Chronos).

#3

For #1 you probably need to better define what “fairly distant” means.

#2 is easy. Light speed is a constant, period.

As for #3, my first instinct is to say that if all the forces really are connected, as every Theory of Everything says they are, you can’t locally alter any one of them without affecting everything else.

But the physics pros are very clever. Maybe they can come up with something.

#4

If you want something closer for your star, tau Ceti is somewhat less like the Sun (a bit redder and cooler), but it’s only about ten lightyears away.

For question number 2, it’s not even clear that it’s meaningful to ask if the speed of light changes. It’s the standard for speed in the Universe, and it’s fair to say that it is in fact the only possible standard for speed.

On question 3: There is no known or theorized way to change the strengths of the fundamental forces, but this one at least is askable (that is to say, it would be meaningful to speak of the strengths of the forces changing). As you speculate, a weakened Strong Nuclear Force would probably make elements more succeptible to fission. This would mean not only that ordinarily unstable elements would fiss more energetically, but also some elements which are ordinarily stable would become unstable. Make sure that you include some energy source to make up for this extra fission energy: The device which causes this change in the forces would need some outside energy source.

#5

For a selection of stars, try this page: Sol Station: Notable Nearby Stars. Not all will be suitable for a life-bearing planet so you’ll have to read the pages.

#6

  1. Here’s a handy (zoomable!) map.

  2. The speed of light is constant in all reference frames in vacuo. The only way you can ‘slow it down’ is by introducing an optically denser medium.

  3. The four fundamental forces are balanced so ablsolutely precariously that the slightest change, down past tens of decimal places, would render “interesting” structures such as stars (and ultimately, life) impossible. Weaken the strong force which holds protons together in the nucleus and the entire atom does indeed fission spontaneously.

#7

This is a bit of a nitpick, perhaps, but the speed of light is contstant in vacuum. Light traveling through matter moves more slowly. So the speed of light in our atmosphere is a little bit slower, and the speed of light in water is slower than that.

Also, if you haven’t studied relativity it may not be clear to you exactly what is meant by “the speed of light is constant”. You might think that if you get in your car and drive down the road at exactly 15 mph, then your speed is constant. But it isn’t constant the way the speed of light is constant. Your car would be moving at 15 mph relative to the road, but at 0 mph relative to you (because you’re in the car moving with it.) The speed of light, however, has the same constant value in every inertial (i.e. unaccelerated) reference frame. That is to say that if I’m “standing still” on the earth watching a beam of light fly by, and you’re chasing after the beam at 1/2 light speed, we’ll both see the beam moving away at roughly 300 million meters/second, even though common sense tells you that you should see it moving at half that speed. This bizarre fact gives rise to all sorts of disagreements about our measurements of distances and time intervals and such.

However, these differences are only really noticable if one of us is moving at a significant fraction of light speed, as in the above example. In normal day to day life, you might be driving along at as much as, say, 80 mph relative to me, but this is still insignificant next to the speed of light, and the differences in our perceptions are too small to be noticed.

I hope this makes sense. I’m sure if I’ve made any errors in this explanation, someone will correct me.

#8

I didn’t notice his post before, but I see SentientMeat beat me to the punch (by a good 3+ hours) on the speed of light changing in a medium, and even used the correct Latin word ending for vacuum in the ablative case. :slight_smile:

#9

Although the speed of light in vacuum shouldn’t be affected by any forces we know of, and there’s no way we know of to cause the other forces to vary, that doesn’t mean that you can’t explore the effects in a science fiction story. The essence of science fiction, of course, is “What if”.

Poul Anderson wrote a novel in which the speed of light did vary from place to place in the universe. The earth emerged from one place where the speed of light (and electrical signals in general) had been retarded, and the result was that everyone became much more intelligent. How would people deal with such a situation? That was the theme of the novel. Its title is Brain Wave, and it’s a classic.

Of course, I doubt that this would be the real effect, but there’s nothing to stop anyone else from speculating about it. As far as I know, though, no one has since Brain Wave came out. So the time is arguably ripe for something like what you suggest.

But if you’re going to write about someplace where the fundamental forces of the universe and/or the speed of light vary, and that’s the foundation of your fictional world, you’re gonna have to do your own research, and quite a bit of it. You’ll have to know more than you’ll get from a SDMB thread. But it will be worth it.

And don’t worry if your result is not strictly scientifically accurate. No one blames Anderson for his accuracy.

#10

By the way, the classic text used by aspiring SF writers to locate stars and planets and to describe them for their stories is Dole’s Habitable Planets for Man. It’s an old book now, and I know I’ve seen more recent guides in the “Writing” sections of the local bookstores. You might want to look for ads in Writing magazines, SF magazines, or, say, Locus.

#11

The moral of the thread is, you can ask about how the universe really is all you want, but the beauty of real sci-fi (not cheesy star wars/trek rip-off paperbacks) is when the writer either predicts new science or makes changes to old science and forms an intriguing story around it, expanding on the consequences of the predictions/changes.

#12

It’s incorrect to say that the speed of light changes in a vacuum; it’s more accurate to say that light propagates slowly through a medium. Photon interaction with the particles in the medium delays the wavefront, but the speed of the photons is either c or nothing.

#13

There is Einstein’s constant, C, which is a fixed number; and there is the actual propagation of massless particles through a medium, c. These are two very different things, although people get them confused all the time.

It is possible for massed particles to move through a medium faster than the local speed of light. This is what produces Cherenkov radiation. However, these still can never move faster than C.

It’s not clear what dwalin thought he was asking with question #2. I hope he comes back and explains the thinking. He may be having more trouble with the science than he thinks.

#14

Checkout Redshift Rendezvous by John Stith for an interesting take on this. It is set on a starship traveling through a weird space where the speed of light is much lower than ours - so people on the starship have to deal with relativistic effects in normal life. It’s quite good, and even has appendices.

#15

This might be a minor hijack. As has been previously mentioned, the speed of light in a vacuum is a constant in all inertial reference frames. However, my basic understanding of general relativity is that gravity wells warp spacetime, in effect turning those regions affected into non-inertial reference frames. Is the speed of light in a non-inertial reference frame still a constant?

#16

Larry Niven wrote of a weapon created by the Slaver species in World of Ptavvs that could supress the weak force, thus acting as a disintegrator ray. I don’t think the physics are correct, but I’m pretty sure he wrote weak force rather than strong force, which would make more sense.

#17

My only advice, given the response here, is do not mess with the speed of light! :eek:

Oh, hang on a minute, you did say your story was science fiction, not science fact. :smack:
If it’s fiction, then do what you want, just try and come up with a way of making it appear possible. There’s plenty of armchair physicists out there who can suspend belief - to a certain extent - for the sake of a decent SF read. :slight_smile:

#18

(Bolding mine.)

Others have dealt with the physics questions better than I could, so I’ll just caution you about something that’s a pet peeve of mine. A constellation, as seen from Earth (or any other given point) is an optical illusion; the stars that make up a constellation may be quite spread out, not occupying a discrete chunk of three-dimensional space. Cygnus, for example, contains Deneb, 3,261 light years from Earth, and also Tau Cygni, only about 68 light years away. So don’t use the word “constellation” as if it describes a place in the Galaxy.

You probably had no such intention, but better safe than sorry.

#19

Indeed, my only thought was to make it somewhat familiar to the reader; I labor under no illusions that constellations have any real existence.

To those working on my lightspeed question, I’m basically asking if lightspeed is ruled by its own fundamental law or if the other laws have any effect. For example, would strengthening electromagnetism make light travel at a different speed? See, this is one of my basic assumptions for the story, and I’d really rather not have to do something else.

#20

I guess I still don’t understand what you’re asking.

When you say strengthening electromagnetism, do you mean changing the relative strength of electromagnetic attraction compared with the strengths of the other three forces? The old “gravity is 10[sup]-42[/sup] times as strong” business?

If so, that would be a field strength change in QED - Quantum Electrodynamics. I don’t believe C enters into any of the basic equations, so that would not change.

But I’m teetering over the border of my formal knowledge by this point.

P.S. IIRC, the speed of light effects in Redshift Rezvendous are local changes in c due to proximity to a superdense object, not changes to the fundamental constant of C. Good book, though.