Can Light Particles Propel Spacecraft to the Speed of Light?

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Discussion Overview

The discussion revolves around the feasibility of using light particles, or photons, for spacecraft propulsion and the implications of the speed of light in physics. It includes theoretical considerations, technical explanations, and conceptual clarifications regarding light propulsion and the nature of light speed.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether it is possible to catch light particles to propel a spacecraft to the speed of light.
  • Another participant argues that photons cannot be caught in a traditional sense, but their momentum can be transferred when absorbed, suggesting that a solar sail could be used for propulsion.
  • Some participants discuss the limitations of reaching the speed of light, asserting that while it is impossible to reach light speed, one could get arbitrarily close.
  • There is a debate about the nature of the speed of light, with some stating it is the rate at which time flows, while others contest this by referencing Maxwell's equations and the properties of space.
  • One participant proposes that the speed of light may relate to the Higgs field, suggesting a connection between mass and light speed.
  • Questions arise regarding the relationship between the speed of light and the concepts of permeability and permittivity of space, with requests for simpler explanations of these terms.

Areas of Agreement / Disagreement

Participants express differing views on the nature of the speed of light and its implications, with no consensus reached on whether it is the rate at which time flows or a consequence of electromagnetic properties. The discussion remains unresolved regarding the relationship between light speed and permeability/permittivity.

Contextual Notes

Participants express uncertainty about the definitions and implications of permeability and permittivity, indicating a need for clearer explanations. The discussion reflects a mix of theoretical and conceptual challenges without definitive resolutions.

Killer slug
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is it possible to catch light particles and have them push you along in some kind of space ship, and if you could would it be the speed of light
 
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No, but apparently swans make good propulsion for early space craft. Light particles or "Photons" are packets of energy that you can't catch. If you were to try and "grab" one with your hand and catch a ride you may be disappointed. Traveling at light speed is impossible for such a large mass as yourself, but seriously swans all the way...
 
Actually, every time a photon hits you and you absorb it, you have "caught" it. And when you do, it transfers its momentum to you. So yes, you could propel a spaceship that way (actually, reflecting them is better...), but you'd need an enormous solar sail to catch enough photons to be useful. And no, you could never reach the speed of light. You could get arbitrarily close to it, though.

Anyway, look here: http://en.wikipedia.org/wiki/Solar_sail
 
"swans"? Is that a technical term.

"Light Sails" have long been a staple of science fiction. I don't know if NASA is doing any research but it would certainly been possible.
 
Why is the speed of light limited to 3*10^8 m/s? What is blocking it from going faster than that?
 
The speed of lights is an absolute maximum to speed, because it is the rate at which time flows. The digits it is expressed as are based on our units of measurement.
 
The speed of light is not the rate at which time flows.

The speed of light is a dictated by the permeability and permittivity of space, as a consequence of Maxwell's equations.
 
Well Watters has explained it clearly...
 
lanman said:
it is the rate at which time flows.

Not sure where I heard that...
 
  • #10
lanman said:
Not sure where I heard that...

In a sense, c is the conversion rate between space and time. In many theoretical papers, "natural" units are adopted, where c = 1, \hbar = 1, etc. So that mass, length, time are all inter-convertible without changing the number.
 
  • #11
russ_watters said:
The speed of light is a dictated by the permeability and permittivity of space, as a consequence of Maxwell's equations.

From the speed of light, did we derive the permeability and permittivity of space, or is it the other way?

Can anyone explain permeability and permittivity of space in simpler terms? I googled those keywords, but gave me pages with lots of greek symbols, which I used to understand in the past, for a short period in my life.
 
  • #12
I would think that the definition of c, the speed of light, would rely somewhat on the Higgs field - that which endows mass upon particles. Massless particles travel at the speed of light, massive ones at less than c.
 
  • #13
jobyts said:
From the speed of light, did we derive the permeability and permittivity of space, or is it the other way?
If I understand the history correctly, I think they were measured about the same time the first accurate measurements of the speed of light were being taken (by Michelson). So the speed of light was separately measured and calculated and found to be the same value.
Can anyone explain permeability and permittivity of space in simpler terms? I googled those keywords, but gave me pages with lots of greek symbols, which I used to understand in the past, for a short period in my life.
Basically, the resistance to passing magnetic and electric fields.
 
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