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Author Topic:   Speed of Light Barrier
Taq
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Posts: 9973
Joined: 03-06-2009
Member Rating: 5.7


Message 116 of 178 (503964)
03-23-2009 5:51 PM
Reply to: Message 112 by Sarawak
03-23-2009 3:13 PM


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?
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.

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Taq
Member
Posts: 9973
Joined: 03-06-2009
Member Rating: 5.7


Message 118 of 178 (503968)
03-23-2009 6:03 PM
Reply to: Message 117 by Perdition
03-23-2009 5:58 PM


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?
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

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Taq
Member
Posts: 9973
Joined: 03-06-2009
Member Rating: 5.7


Message 129 of 178 (505281)
04-09-2009 6:49 PM
Reply to: Message 128 by onifre
04-08-2009 6:17 PM


In an effort to make sense of it a bit more for you, I would say that "speed", also, only makes sense to the person observing the object in motion.
A photon heading toward Earth at (c) is said to be traveling at light speed toward us, from our frame of reference. But, from the frame of reference of the photon, it is the Earth that is traveling toward it at (c). In other words, to the photon, it is not moving at all. Yet, when we, on Earth, look at the photon in our frame of reference we are stationary and it is moving at a defined speed.
[uber-nerd nit pick]It is actually stranger than this. We don't actually observe a photon moving. We simply measure the time it takes to get from point A to point B. In between point A and point B it can be in any number of places. It is only whe a photon interacts with matter does it appear in just one place.
So might it be more accurate to describe the speed of light as the speed of the propogation of light?
[/uber-nerd nit pick]

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Taq
Member
Posts: 9973
Joined: 03-06-2009
Member Rating: 5.7


Message 133 of 178 (505303)
04-10-2009 12:37 AM
Reply to: Message 132 by onifre
04-09-2009 8:52 PM


From the observer’s point of view, the photon moves with measurable velocity, measurable frequency, measurable energy. The time experienced by the photon is still zero from start to finish of its journey, but the observer still knows it is moving at a particular pace and also vibrating as it goes. When it is said that a photon is "observed" I don't mean visually followed, I mean measured.
It was a minor and very tedious nit pick. I just happen to really enjoy these types of discussions.
I find the differences between our macroscopic experience of the world and the microscopic world of quantum mechanics to be a very exciting difference. It's not as if we measure the speed of light like we would a car going down the freeway. It is more like measuring the velocity of a bullet by measuring the time it takes between the bullet being fired and the bullet striking a target 200 yds down range. We don't see the bullet in between with our naked eye, but we do hear the bang and then see the strike. Light is somewhat like this, but even stranger.

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