Speed of Light Barrier

Photons have no mass. For objects with mass m moving at velocity v relative to you, apply this equation to find the mass you'll measure: As you can see, the denominator of that equation becomes 0 for v==c, and so the mass you perceive will be infinite for objects traveling at the speed of light, and the impossibility of infinite mass explains why you'll never perceive any object with non-zero mass traveling at the speed of light. For one thing, it would take infinite energy to accelerate a mass, no matter now slight, to the speed of light.So obviously the only things that can travel at the speed of light must have no mass, and the photon fills the bill in this respect.--Percy

The universe is thought to be unbounded, so there's no such thing as objects at the boundary, but there are certainly objects at the boundary of our perception. The further away the object the faster it is receding from us due to the expansion of the intervening space. Objects far enough away are receding from us faster than the speed of light, but of course we cannot see them because the light will never reach us.But the portion of the recession velocity contributed by the expansion of space is not part of the velocity of the object. Imagine a broad rubber strip stretched between your hands and upon which ants are walking. Ants at opposite ends of the strip have a velocity relative to one another as they walk randomly about. When you begin moving your hands apart and stretching the rubber strip longer and longer so that the ants recede from one another, the velocity contributed by your stretching of the rubber strip is not part of the ants' velocity.The stretching of the rubber strip is analogous to the expansion of space, and that expansion is separate from the velocity of objects within that space.--Percy

You know, things like radio waves, microwaves, visible light, UV rays, x-rays, gamma rays. If the physics is right, then yes. As the observations seem to match what physics predicts, we can pretty confidently state that nothing can move faster than the speed of light.Again, the sound barrier was merely a barrier due to technological gaps. The speed of light is a physical barrier that cannot be broken due to the laws of physics.

Relativity theory is very mathematical. Physicists and cosmologists plug values into the relativity equations to make predictions, then they peer through telescopes or otherwise make measurements, and in this way they verify the predictions of relativity theory. This has been done over and over and over again with increasingly novel predictions. This kind of repeated confirmation is the hallmark of solid theory.Have you considered the possibility that you might be rejecting relativity prematurely? That perhaps a bit more study might be appropriate before drawing conclusions?--Percy

Nothing is moving.Relative to us, galaxies appear to be moving at faster than (c) - light speed. But in fact, they are not moving much, it only appears that way to us because the space between the galaxies is expanding. Save it from what, your take on it?You are simply wrong in your understanding of this subject.

---

"I smoke pot. If this bothers anyone, I suggest you look around at the world in which we live and shut your mouth."--Bill Hicks"I never knew there was another option other than to question everything"--Noam Chomsky

Because they are zero rest-mass partciles. Given the need for you to ask the above question, it is abundantly clear that you are in no position to make such statements. All that is clear is that you are confused. No biggie - there are not many that are not confused by relativity...

It certainly appears that we are not going anywhere at the speed of light any time soon.So, since I believe that humans will eventually colonize the galaxy, we will have to go star hopping. What would be the maximum reasonable speed, relative to c, that we could attain?

An ion drive would be limited solely by the amount of fuel it could carry, and if some kind of ramjet capability is possible then the sky's the limit, you could put as many 9's after the decimal place as you like.--Percy

Tau Zero

Interesting thread topic idea, interstellar travel and associated difficulties.To keep it pertinent to the EvsC forum maybe it could include some thought about the problems posed by the evolution of man under those constraints and whether we would be suitable to re-inhabit a planet after traveling for that duration through space. The issues are more technological than theoretical in nature.

quote:

---

OK, so the speed simply isn't there for a quick flight over 4.3 light years. But there is an even bigger problem than that. How would these interstellar spaceships be fueled? According to Brice N. Cassenti, an associate professor with the Department of Engineering and Science at Rensselaer Polytechnic Institute, at least 100 times the total energy output of the entire world would be required for the voyage. "We just can't extract the resources from the Earth," Cassenti said during his conference presentation. "They just don't exist. We would need to mine the outer planets."

​

For mankind to extend its reach into the stars, we need to come up with a better plan. Even the most advanced forms of propulsion (even anti-matter engines) cannot make the gap seem any less massive.

---

Which, if it proves true, leaves us time until the sun expands or the earth's core cools enough for the magnetic field to disappear or maybe the stability of planet orbits will cease before that.There is also the YEC problem that after traveling toward the stars for a period of time they may simply disappear as the light created in transit is all there ever was..Which raises the question, with an expanded sun would some of the other moons of the solar system become habitable with the use of terraforming?Maybe we should seed the appropriate lifeforms to start the process now..

I've always been attracted to the idea of a Bussard ramjet. The spacecraft produces large magnetic fields which funnel interstellar hydrogen into a fusion reaction chamber. You still have to be going pretty fast for the ramjet to function, but at least it gets around the ineffeciency of carrying all of the fuel. Also, the effeciency of the ramjet increases with speed. There's a wiki page with all of the details.

My question, and this was a question of some interest before I dropped out of my physics major and switched to philosophy, is what about the laws of the Universe make the speed of light the ultimate barrier. I mean, I can understand that something with mass would need infinite engergy to reach c, but why can't something without mass go faster? Do they have a tentative answer about that yet?The more we answer the more we find we can ask.

There is a hypothetical particle that can go faster than the speed of light. It is called a tachyon. The slowest it can go is the speed of light. Strangely enough, it is though that it actually gains speed when it loses energy. Read more here: link

The laws of cause and effect.

---

"I smoke pot. If this bothers anyone, I suggest you look around at the world in which we live and shut your mouth."--Bill Hicks"I never knew there was another option other than to question everything"--Noam Chomsky

The laws of the universe are really a metaphore for the phenomena of how the universe operates. Layman take the word "law" too literally. This is an anthopomorphic term conjured in the minds of men. In other words, we see through human-centered glasses and attempt to label things on the edge of human comprehension with human centered language. Asking why matter has a speed limit is akin to asking why does the universe aka spacetime exist in the first place. These two concepts are one in the same, are fundamental in nature and have yet to be fully understood. There is speculation of faster than light zero-mass particles/energy called tachyons (yes, Star Trek borrowed this idea from main stream science). However, this idea is purely hypothetical with no evidence yet supporting it.The limit of the speed of light (or more accurately electromagnetic radiation) in a vacuum is tied up to the very concept of spacetime itself. They are indistinguishable as described by Einstein's Special/General Theory of Relativity. A good book that describes the nature of spacetime and the speed of light limit is Brian Greenes's "The Fabric of the Cosmos" and the classic Hawking book "A Brief History of Time". I whole-heartedly agree with this. If we stop asking questions we become non-sentient beings.

---

For me, it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring.
Dr. Carl Sagan