A few things in relation to FTL travel

[sparta98]

When I get bored I like to think about how certain things work in space. One of the topics that wound up on my mind was this: if the speed of light is faster than the speed at which radio waves travel, would it be ( in theory) more effective to send unmanned "messenger shuttles" than to use something more like a space version of a landline, or is my reasoning faulty?

The second topic is the subject of a weird joke." If you are in a car going faster than the speed of light, will the headlights work?" at first I thought it was funny, but when I tried to guess what would happen, I realized I didn't know.


Does anyone know the answers? (sorry if these seem like dumb questions, because they probably are.

 

[MeteorWayne]

The speed of light, and the speed of radio waves are the same. It really is the speed of electromagnetic radiation, though it is called the speed of light. Light is just a narrow band of the electromagnetic frequency/wavelength spectrum.

 

[sparta98]

Ok, that makes more sense
That brings to mind something else...
If the speed of radio and light are the same measurement, what happens if you are at the speed of light and you were to turn on your radio?(provided there was something to detect)

I have a feeling I messed up my reasoning here too...

(thanks for the answer Wayne)

 

[MeteorWayne]

Ok, that makes more sense
That brings to mind something else...
If the speed of radio and light are the same measurement, what happens if you are at the speed of light and you were to turn on your radio?(provided there was something to detect)

I have a feeling I messed up my reasoning here too...

(thanks for the answer Wayne)

No problem. I didn;t have time to answer your other question earlier. Since nothing with mass can travel faster than the "speed of light" your question is invalid. But say you are doing 0.9999 of the speed of light (not realistic, but possible at least if you have almost unlimited energy), the light will leave you at the speed of light relative to you, but will only be traveling the speed of light. I know, this stuff makes your brain hurt...it does that to me too.

 

[sparta98]

Hmmm... I have a feeling humanity is doomed to this little portion of the galaxy unless we invent some good teleporters..

.

 

[MeteorWayne]

Go for it. But I'd advise not holding your breath in the meantime.... :shock:

 

[sparta98]

Unless people start living forever, I don't think we'll ever understand this universe (or teleprters teleport themselves here)

 

[Valamir]

Unless people start living forever...

That may very well be the only key to interstellar travel. Sci-fi has produced some wild and fun ideas, but everything we actually know seems to indicate that super-luminal travel is impossible. And even if it were possible, we might have to face another uncomfortable fact: we might not be a smart enough species to ever hope to understand the physics involved.

What may be possible is that genetic engineering advances will allow us to tweak our own evolution so that disease and degeneration become a thing of the past. That doesn't mean we will live forever (immortality will have to be left to the gods), but a two hundred year journey won't be a big deal when man's mortality is defined by accident or war rather than disease and degeneration. Don't hold your breath though, I think that time is yet many centuries in the future - well long past the 23rd and 24th century settings of pop sic-fi. We'll get there eventually, provided we don't off ourselves and become extinct first.

 

[sparta98]

Depressing... It might happen, but we'll all be long dead

I'll start the teleporter...
(being serious now)
Are there any answers to my other questions though, or are they also unfeasable? (thanks )

 

[SpeedFreek]

Are there any answers to my other questions though, or are they also unfeasable? (thanks )

I thought all your questions had been answered.

if the speed of light is faster than the speed at which radio waves travel, would it be ( in theory) more effective to send unmanned "messenger shuttles" than to use something more like a space version of a landline, or is my reasoning faulty?

Light and radio waves travel at the same speed, as they are the same thing.

If you are in a car going faster than the speed of light, will the headlights work?" at first I thought it was funny, but when I tried to guess what would happen, I realized I didn't know.

You cannot travel faster than light, or even at the speed of light itself. But if you travel slower than light, however fast you are moving, light always travels ~300,000 km/s faster than yourself! The speed of light is always measured to have the same value, relative to whoever is measuring it, whatever their own speed relative to anything else.

I can't see any other questions.

 

[sparta98]

I must have had a blonde moment going at the time...
Thanks guys

 

[neilsox]

If you are traveling away from Earth at 0.9 c, a special radio receiver may be able to detect signals from Earth, but they will be stretched out, due to time dilation. If you record the signals and play them back ten times faster they will sound normal. Conversely if you are approaching Earth at 0.9 c you need to play back the recordings ten times slower to sound normal. The reverse occurs for transmissions you send to Earth. At Earth the signals will need to be slowed by ten times to be intelligible, if you are approaching Earth at 0.9c. Also the carrier frequency is shifted up by ten times. At 0.9999 c communication is likely impossible as the shift is 10,000 times, but perhaps we can invent a recorder capable of a 10,000 times shift in speed from record to playback. This is called doppler shift. Head lights behave tha same way = the light is shifted out of the visable band for the distant observer. Neil

 

[flyer456654]

Just outta curiosity, would it be possible to exceed the speed of light if a mass reduction device was created? That is to say, you have a ship that has a mass of 100 tons. The ship has a device that can create a negative mass field (i know not possible right now). This negative mass field produces a negative mass around the craft of -101 tons. This means that the net mass of the ship is -1 ton. Would it be possible to exceed the speed of light if this occured? Secondly, would the negative mass field have to fundementally alter space or could it actually work in normal physics? Lastly, does negative mass actually occur naturally?

 

[sparta98]

Do you mean like in Mass Effect? Or am I just too much into my video games.

 

[flyer456654]

Well first off I LOVE Mass Effect and Mass Effect 2. And yes, I think that the Mass Effect Field is what would be most similar. Great example of the negitive mass effect that I wanted to postulate here. Would this allow FTL travel since it is a very convienient loophole through the whole "mass cannot achieve 1.00C". Since it will have negative mass then any amount of energy would allow it to get to FTL right? Sorry I have never had physics so I can only guess maybe someone can back me up with facts?

 

[origin]

Well first off I LOVE Mass Effect and Mass Effect 2. And yes, I think that the Mass Effect Field is what would be most similar. Great example of the negitive mass effect that I wanted to postulate here. Would this allow FTL travel since it is a very convienient loophole through the whole "mass cannot achieve 1.00C". Since it will have negative mass then any amount of energy would allow it to get to FTL right? Sorry I have never had physics so I can only guess maybe someone can back me up with facts?

Well, since anything with mass cannot reach the speed of light and anything with out mass can only go the speed of light, then sure negative mass can go FTL. The problem is there is no such thing as negative mass. A mass effect machine is as likely as Prof. Dumbledor using magic for FTL.

 

[sparta98]

It sucks that the universe seems to have filled in the loopholes with cement... Maybe something will present itself

 

[ramparts]

Actually, the universe uses that "cement" for a very good reason - if FTL travel were allowed, effects could proceed their causes and the whole notion of cause and effect would be thrown off. Assuming causality is something the universe wants to keep, then the laws of physics have to conspire in some way to prevent FTL travel.

 

[ramparts]

Well first off I LOVE Mass Effect and Mass Effect 2. And yes, I think that the Mass Effect Field is what would be most similar. Great example of the negitive mass effect that I wanted to postulate here. Would this allow FTL travel since it is a very convienient loophole through the whole "mass cannot achieve 1.00C". Since it will have negative mass then any amount of energy would allow it to get to FTL right? Sorry I have never had physics so I can only guess maybe someone can back me up with facts?

Well, since anything with mass cannot reach the speed of light and anything with out mass can only go the speed of light, then sure negative mass can go FTL. The problem is there is no such thing as negative mass. A mass effect machine is as likely as Prof. Dumbledor using magic for FTL.

While we're talking about physically unrealistic mathematical constructions, negative mass wouldn't actually make something go faster than light - as far as the speed limits are concerned, having negative mass is no different than having positive mass. The mass-energy equivalence is:

E^2 - (pc)^2 = (mc^2)^2

where E is energy, p is momentum, m is mass, c is the speed of light, and 2 is the number after 1. For an object at rest (p=0), this becomes the famous E=mc^2. For an object with no mass (m=0), this becomes E=pc. Since velocity is related to energy and momentum by:

pc^2 = Ev

substituting in E=pc gives v=c for massless particles. So massless particles, like light, travel at the speed of light. Cool.

Now say we have an object with negative mass. Well, since it gets squared in the first equation, its energy is the exact same as if it had the same amount of positive mass, so it'll travel at the same speed.

But say m was an imaginary number; then the right hand side of the first equation would be negative, E would be less than pc, and v would thus be greater than c. So it's an imaginary mass (imagine that!) which would give you FTL travel. But I'm not sure what imaginary mass would mean

Origin, I know you know all this so pardon the over-explanation, it's for the general benefit

 

[sparta98]

I think I follow you, but math is my worst subject.

What if m were equal to zero then?( I get that it isn't possible at this point in time)



Edit/ sorry, I just found the answer in your explanation

 

[ramparts]

For an object with no mass (m=0), this becomes E=pc. Since velocity is related to energy and momentum by:

pc^2 = Ev

substituting in E=pc gives v=c for massless particles. So massless particles, like light, travel at the speed of light. Cool.

Having no mass is absolutely possible - several different elementary particles, including photons (light particles) have no mass. They all travel at the speed of light, for the reasons I just quoted.

 

[flyer456654]

OK i get the math...but I have an issue with it. If negitive net mass can be created, why would it still not be possible to get past light speed. By having negative mass, you essentially have less than no mass. I get the mathematical reason why it would still require an a$$ ton of energy to get to the speed of light, but I don't understand common sense wise. I mean when I push something that weighs 100lbs it moves a lot slower than when I push something with 1lbs. I guess the best similarity I can come up with involves elements. Lets say Iron is a positive mass object, Oxygen is a 0-mass object, and Helium is a negative mass object. The object with mass (iron) needs a butt load of energy to be lifted off the ground. Oxygen is kinda nulled out, where ever you put it on earth it kinda just chills (might be off but i'm not a chem guy just go with the example), but Helium, by its nature, floats away without any energy needed. Now I know that isn't the best example but it is the easiest to comprehend for me. Now lets translate this to FTL. An object with mass would require a rediculous amount of energy to get to light speed (more than is available, kinda like trying to throw iron in the air and make it stay there) making FTL impossible. An object with no mass travels at the speed of light but cannot exceed it (kinda like just chilling in one place like the oxygen). But if the object has negitive mass, that is to say net negative mass, why wouldn't it inheritly want to go faster than the speed of light, when a positive energy is put toward it (kinda of like helium inheritly wanting to rise on earth). I understand that it would take an infinite amount of negitive energy to get it going to FTL but wouldn't positive energy force it to inheritly want to go FTL.

Once again, I totally understand the math behind it. I get that you square it and thus it doesn't matter if it is negative or positive. My problem is with the conceptual idea. I mean, in my mind, I feel that a negitive mass object theoritically would want to go FTL rather than below FTL (when a positive energy is placed against it).

 

[MeteorWayne]

Since negative mass objects don't exist, it's a moot discussion.

 

[flyer456654]

Shoot Wayne. (lets look at the past) I guess since human flight is an impossibility it is moot to even attempt to do it. Since landing on the moon is impossible we might as well not try. Just because something doesn't exist currently doesn't mean that it won't ever exist...and on a second note, I said theoretically. I know that negitive mass does not exist but "theoretically" if it did what would be the answer to my question. And last time i checked, we don't know if negitive mass exists. If the idea that negitive mass would inheritly want to go FTL...then how would we ever detect such an event? (Has anyone definitively disproven tachyons or for that matter proven them?) Its something to say that current theories and evidence point to it not exisiting, but to simply shoot down a discussion (and a valid question based purely on theory) is kinda mean. I'm not saying that it can be done, just wanted to have a better understanding of the theories. So Wayne, my question is not moot since it is based on attempting to better understand the THEORY. Oh and can you prove to me definitively that negitive mass does not or cannot exist (in dumb person terms since I am not a physics person).

To reiterate, I am attempting to learn about a theory and would like a nice explaination of certain aspects. I also understand that negative energy doesn't exist, but since we are discussing pure theory existance or non-exisitance doesn't matter.

 

[ramparts]

Oxygen, helium, iron, and every other element all have positive mass. So you can visualize some of them as having zero or negative mass if you really want, but then don't expect that faulty visualization to generalize to faster than light travel.

Your question is really hard to answer because there are lots of instances in physics, especially modern physics, where the Universe doesn't work as common sense or everyday intuition would tell you. Your common sense was developed by watching how things work here on Earth, where nothing's too massive (or has negative mass) and everything moves at really slow speeds. That common sense shouldn't necessarily apply in vastly different circumstances. So there's just not much point then in coming up with a common sense explanation - you're better off studying this stuff some more so you change your intuitions

To put it a bit more roughly, the Universe doesn't care if in your mind you "feel that a negitive [sp] mass object theoritically [sp] would want to go FTL rather than below FTL." Energy is dependent on the square of an object's mass, not just the mass itself. That's how the Universe works.

Also, "butt load" isn't really used in physics. Since science runs on the metric system, physicists more commonly use the "metric buttload."