Why can't we reach to Speed of light at Space?

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Discussion Overview

The discussion revolves around the question of why it is impossible to reach the speed of light in space, exploring the limitations of spacecraft propulsion, relativistic effects, and the physics governing high-speed travel. Participants examine theoretical and practical aspects of acceleration, mass increase, and energy requirements in the context of both rockets and particle accelerators.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants propose that the absence of friction in space allows for theoretically unlimited acceleration of spacecraft, questioning what limitations exist.
  • Others argue that as an object's speed increases, its relativistic mass approaches infinity, complicating the ability to reach light speed.
  • A participant mentions that particle accelerators like the LHC can only achieve speeds close to the speed of light, highlighting the immense energy required for such acceleration.
  • There is a discussion about the Tsiolkovsky rocket equation and its implications for maximum rocket velocity, with some participants asserting that rockets cannot exceed their exhaust velocity.
  • Some participants challenge the concept of increasing mass with speed, suggesting that the energy equivalent does not imply an actual increase in mass.
  • Concerns are raised about the understanding of Newton's laws in the context of rocket propulsion and the limitations imposed by fuel requirements.
  • Several participants express uncertainty about the breakdown of physical laws at light speed, with conflicting views on whether such a breakdown occurs.
  • There is a mention of the subjective nature of describing phenomena at light speed, with some participants asserting that special relativity is well-understood while others find it difficult to articulate.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the implications of relativistic mass, the applicability of the Tsiolkovsky equation, and the understanding of physical laws at high speeds. The discussion remains unresolved, with no consensus on several key points.

Contextual Notes

Limitations include varying interpretations of relativistic effects, the applicability of classical mechanics to high-speed scenarios, and the dependence on specific definitions of mass and velocity in different reference frames.

  • #121
Neandethal00 said:
. Then we turn around and say mass increases with velocity.
I don't have any idea who that "we" is that you are talking about. I'm not aware of any knowledgeable physicists who says any such thing and you will not find any such members of this forum saying so. There are HUNDREDS of threads on this forum pointing out that objects do NOT gain mass in that manner, they gain energy.
 
Last edited:
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  • #122
rootone said:
Since energy and mass are equivalent in relativity, the object's greater energy can be considered as greater mass.

Good, this can be one interpretation of effects of velocity on special relativity.
My thinking is it is not mass that increases, it is the inertia that increases requiring larger energy to move through space.
We know very little about interaction between 'empty space' and matter.

If there are 'fish scientists' in the ocean, the fish scientists formulate theories of physics to explain everything to other 'fish' totally ignoring the 'water'.
That's what we (Yes, Phind, I consider myself a scientist, it is called self criticism) are doing now.
 
  • #123
Neandethal00 said:
there are 'fish scientists' in the ocean, the fish scientists formulate theories of physics to explain everything to other 'fish' totally ignoring the 'water'.
We do that with light because there is no "medium" required for it to propagate through - no "ether". This might not always be the case with other phenomenona.

Neandethal00 said:
My thinking is it is not mass that increases, it is the inertia that increases requiring larger energy to move through space.
That's right. This is best demonstrated using a force 4-vector: ##F_μ = γ\frac{∂p_μ}{∂t}##. This implies that the force required to accelerate an object at a constant value tends to infinity over time (for rectilinear motion).
 

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