Can speed of light be faster with this?

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Discussion Overview

The discussion revolves around the theoretical possibility of constructing a long steel rod in space and whether it could be manipulated to exceed the speed of light. Participants explore the implications of mass, resistance, and the physical limitations imposed by relativity.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant proposes a hypothetical scenario involving a 300,000 km long steel rod anchored at one end, suggesting it could be pushed or pulled to achieve extreme speeds.
  • Another participant questions the molecular dynamics involved when pushing an object, indicating a need for clarification on the mechanics of motion.
  • Some participants argue that the mass of an object remains constant regardless of its location in space, emphasizing that weight changes but not mass.
  • Concerns are raised about the feasibility of rotating the rod, with one participant noting that inertia would prevent it from moving faster than the speed of light.
  • Another participant asserts that no material exists that is both light and strong enough to support such a structure, and that nothing with rest mass can accelerate to the speed of light.
  • It is mentioned that compressive forces in materials travel at the speed of sound, implying that pushing an object does not result in instantaneous movement across its length.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the feasibility of the proposed scenario and the underlying physics, with no consensus reached on the possibility of exceeding the speed of light.

Contextual Notes

Limitations include assumptions about material properties, the nature of forces in space, and the interpretation of physical laws such as inertia and the speed of sound in materials.

Archangel
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Can this be doable in theory? Because who in the right mind would build this :)

Let us imagine if we could build a steel rod, that has mass of 1 Kg, that has length about 300000 km. Yeah I know, impossible, but how about some material that can weight 1Kg or even 10Kg. But in space even 1000 tons of material is like a feather.

Now let's say that we anchor one side to earth, asteroid or whatever.
If rod is r in circle, then quarter of circle would be 471000 km.
Now few cm from anchor we push or pull rod for a 1/4 circle, because there is no resistance in space/universe, or it is minor, it could be pushed or pulled by a second or fraction of a second. So the far end would cross 471000 km by a second or less.
 
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What do you think happens on a molecular level when you push something?
 
Archangel said:
But in space even 1000 tons of material is like a feather.

The mass of an object doesn't change by moving it to space, it's weight will change but not it's mass.

Archangel said:
Now let's say that we anchor one side to earth, asteroid or whatever.
If rod is r in circle, then quarter of circle would be 471000 km.
Now few cm from anchor we push or pull rod for a 1/4 circle, because there is no resistance in space/universe, or it is minor, it could be pushed or pulled by a second or fraction of a second. So the far end would cross 471000 km by a second or less.

Are you saying that you want to turn this rod in a circle with one end being the center of the circle and the other end being the edge of the circle? I believe that is what you are saying, but it's a little difficult to tell. Anyway, you say there would be little to no resistance to pushing or pulling on this rod. This simply is not true. If you are rotating the rod it has a moment of inertia, which is the resistance to change in rotation. If you are simply moving the rod (not rotating) it has inertia (it's mass) which is a resistance to change in momentum. You will not be able to move this rod faster than the speed of light.
 
Last edited:
Archangel said:
Can this be doable in theory? Because who in the right mind would build this :)

Let us imagine if we could build a steel rod, that has mass of 1 Kg, that has length about 300000 km. Yeah I know, impossible, but how about some material that can weight 1Kg or even 10Kg. But in space even 1000 tons of material is like a feather.

Now let's say that we anchor one side to earth, asteroid or whatever.
If rod is r in circle, then quarter of circle would be 471000 km.
Now few cm from anchor we push or pull rod for a 1/4 circle, because there is no resistance in space/universe, or it is minor, it could be pushed or pulled by a second or fraction of a second. So the far end would cross 471000 km by a second or less.

This is completely impossible for the following reasons;

1. There is no material in existence both that light and strong.
2. No matter what the mechanism nothing with a rest mass can accelarate to c. There is no tricking relativity here!
 
Archangel said:
Let us imagine if we could build a steel rod, that has mass of 1 Kg, that has length about 300000 km. Yeah I know, impossible, but how about some material that can weight 1Kg or even 10Kg. But in space even 1000 tons of material is like a feather.

I'm afraid you're mixing up http://en.wikipedia.org/wiki/Weight" . 1000 tons in space would be just as hard to move as 1000 tons on Earth (well it would be a little easier thanks to the lack of friction).

Now let's say that we anchor one side to earth, asteroid or whatever.
If rod is r in circle, then quarter of circle would be 471000 km.
Now few cm from anchor we push or pull rod for a 1/4 circle, because there is no resistance in space/universe, or it is minor, it could be pushed or pulled by a second or fraction of a second. So the far end would cross 471000 km by a second or less.

Compressive forces don't travel instantly through materials unfortunately, they travel at the speed of sound. When you push an object the first atoms bang into the next, which bang into the next etc. Nothing faster than light here :)
 
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