Why does everyone assume the speed of light is the fastest we can go?

[Rukentuts]

Ensign Ro was tougher and probably the cutest of the bunch. Not hot, but definitely cute.

[lanerios]

No what changed is that those claims where made by people with NO "tech"nology

WRONG!

Those people were scientists, made statements with the technology (or lack thereof) in their current day

Right now

Scientists, make statements with the technology (or lack thereof) in their current day.

What we see as technology now, might be seen as completely useless years down the line. It is exactly the same.

[Wikiy]

And people on these boards like to suggest that no great scientific advances are made anymore...

I think they're talking gibberish.

[Deleted]

Here's something I have yet to understand..
If photons have no mass, how does a solar sail work ?

[Garnier Fructis]

Here's something I have yet to understand..
If photons have no mass, how does a solar sail work ?

Because mass isn't what's important, it's momentum. While photons do not have mass, they have momentum, and as such are able to exert a radiative pressure on a solar sail. Fun fact, if you make the sail out of reflective material the pressure is doubled.

We tend to associate momentum with mass because for large objects where Newton's laws approximately hold, momentum is defined as mass * velocity. For a photon, momentum is instead defined to be energy / speed of light.

[Deleted]

Because mass isn't what's important, it's momentum. While photons do not have mass, they have momentum, and as such are able to exert a radiative pressure on a solar sail. Fun fact, if you make the sail out of reflective material the pressure is doubled.

So I guess the answer is that light just works that way ? Pretty sure that the formulas from my physics class had a mass factor in all of them, but we weren't working on massless objects.

Yeah just thinking about it the models I have simply do not work for massless objects. Silly non-Newtonian physics.

[Garnier Fructis]

So I guess the answer is that light just works that way ? Pretty sure that the formulas from my physics class had a mass factor in all of them, but we weren't working on massless objects.

Yeah just thinking about it the models I have simply do not work for massless objects. Silly non-Newtonian physics.

The funny thing about physics is that it only gets weirder as you learn more.

[Gheld]

So I guess the answer is that light just works that way ? Pretty sure that the formulas from my physics class had a mass factor in all of them, but we weren't working on massless objects.

Yeah just thinking about it the models I have simply do not work for massless objects. Silly non-Newtonian physics.

The answer is all particles have energy. As defined by E^2={mc^2}^2+(pc^2)

If a particle is at rest, its energy is defined by E=mc^2. If a particle has no mass its energy is defined by E=pc. (momentum times the speed of light). And it's momentum can then derived to be it's energy divided by the speed of light. Albert Einstein et. al.

EDIT:

The funny thing about physics is that it only gets weirder as you learn more.

You mean like the fact that given Heisenberg's uncertainty principal, because a photon has a fixed, known, speed, one therefore has absolutely no conceivable location while in transit?

[Woebegone]

If a particle is at rest, its energy is defined by E=mc^2. If a particle has no mass its energy is defined by E=pc. (momentum times the speed of light). And it's momentum can then derived to be it's energy divided by the speed of light. Albert Einstein et. al.

Does this mean that if I trap photons between two 100% reflective surfaces, I can just keep gathering energy from the momentum flips?

[Psilar]

Einstein talking about space-time quite a bit. Currently we exist in this space-time. As far as we can tell light only travels so fast in space-time. Warp drives move and bend space-time and therefore get around the idea of traveling IN IT. You're not actually traveling in space-time but having it move around you. In other words there are potential ideas out there right now that would enable faster than light travel.

Light only travels so fast in a vacuum. This doesn't mean we can't go faster with some creative out of the box thinking. Nuclear fusion would help too...

[Deleted]

Nuclear fusion would help too...

You would need an infinite amount of energy to get to the speed of light through conventional means, and we have no idea of how we can manipulate space time yet. Nuclear fusion is not going to change that.

Does this mean that if I trap photons between two 100% reflective surfaces, I can just keep gathering energy from the momentum flips?

Is there such a thing as a 100% reflective surface ?

[Deleted]

Is there such a thing as a 100% reflective surface ?

Nop. If that was the case we'd be a solar driven society

[Kouki]

This really perplexes me sometimes. Why does EVERYONE assume and think that the speed of light is the fastest speed we can go? Just cause we havent discovered how to or understand the science behind it doesnt mean that the speed of light is the fastest and ONLY way we can go.

The Speed of Light is A theory as is any Theory in Science its only Right till proven Wrong with evidence.

The speed of light is considered to be solid because no matter how fast you fly away from me and i shine a light on you, you will see the light hit you instantly.
Even if you fly towards me you see it at the same speed.

The reason is "Time Dialation" Meaning you slow down, minutes to you at the speed of light are months to the rest of us.
And because gravity and speed of light are the same, we can prove in hundreds of ways the speed of light.

And its not new knowledge it was known before Einstein.

[Deleted]

Nop. If that was the case we'd be a solar driven society

Well it would probably have to take the energy from somewhere

[Woebegone]

Is there such a thing as a 100% reflective surface ?

No. Purely theoretical pondering. Fairly certain there will always be some absorbtion.

[Senathor]

I seriously don't think anyone assumes that. I never hard anyone say "we'll never travel faster than the speed of light ever".

[Priestiality]

People assume that our primitive physics is the end all and be all.

Primitive physics? As opposed to what exactly?

[Reeve]

Does this mean that if I trap photons between two 100% reflective surfaces, I can just keep gathering energy from the momentum flips?

No. Either the reflective surfaces move slightly with each impact of the photons, or they are fixed, and the full amount of energy stays with the photon. No energy is gained in the system.

[ShamanTankFTW]

Didn't NASA just make a statement not too long ago that they were in the process of creating/theorycrafting (whatever the term is) something that would take them faster than light speed? Would look for a link but I am too lazy. I know they mentioned not too long ago; go look it up.

---------- Post added 2013-01-09 at 05:19 AM ----------

Primitive physics? As opposed to what exactly?

Uhh, I would assume non-pimitive?

[Woebegone]

Not really sure how to do the calculations, but if decently sized ship crashed into Earth at 50% of c, it would probably leave a crater the size of Florida and wipe out all life on Earth in a fiery blaze of fire.

This thread has grown way too fast for me to keep up with my sporadic posting habits, but I just had to pick this one out. Anyone here got any idea what would actually happen?

Asteroids hit the atmosphere at something like 0,01% c (ballpark), so we can't even use those as a reference. My guess is that something moving at 50%c would hit the atmosphere so fast that air might as well be solid matter. Any kind of heat shielding would be utterly pointless, no matter how advanced your tech is, you'd just disintegrate in a chain of fusion explosions somewhere in the upper atmosphere, maybe engulfing half the planet in a ball of fire and radiation as you go. Actually the carbon fiber compounds we currently use for heat shielding might even make things worse.

(hey, this is still remotely related to light speed...)