Can you stand on enough concentrated light?

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Discussion Overview

The discussion revolves around the hypothetical scenario of standing on a concentrated beam of light, such as a powerful laser, exploring the physical implications and feasibility of such an action. Participants consider various aspects including the mechanics of photon interaction, the necessary conditions for support, and the theoretical limits of this concept.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants suggest that if photons are directed upwards, they could theoretically counteract gravity by impacting the bottoms of shoes.
  • Others argue that a very powerful light source and a highly reflective mirror would be necessary to support a person's weight, citing specific energy and power calculations.
  • It is noted that the effectiveness of the mirror is crucial, as any absorption of energy could lead to melting or deformation, reducing its reflective capability.
  • Some participants interpret the original question as asking for a physical support similar to a solid object, concluding that this is not feasible.
  • There are suggestions that with the right angle of reflective shoes, it might be possible to walk away from the light source, but remaining stationary would be problematic.
  • Concerns are raised about the energy densities involved and the potential gravitational effects of such a concentrated beam of light.
  • Some participants emphasize that the original question disregarded the heat and balance issues, which are significant in practical terms.
  • There is a mention of needing near-perfect mirrors to avoid heating and damage from the light beam.
  • One participant draws a distinction between standing and other forms of movement, such as walking, in relation to the beam.

Areas of Agreement / Disagreement

Participants express a range of interpretations and opinions, with no consensus on the feasibility of standing on a beam of light. Some agree on the theoretical possibility under specific conditions, while others maintain that the original premise is fundamentally flawed.

Contextual Notes

Limitations include assumptions about the nature of light and its interaction with matter, as well as the practical challenges of creating and maintaining the necessary conditions for standing on a beam of light.

An Open Mind
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If you had so much condensed light, so a laser beam, let's say all of the suns energy output put into 1 single beam of light. Could you walk on it? Forget about the heat, the balance you would need and the burn you would get. So your invincible pretty much.

Can you stand on enough concentrated light?
 
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I think it depends which direction the photons are moving. Photons do impact objects and move them slightly (I think there was a gold foil experiments at some point in time).

So, I believe it's possible if the photons are opposing the force of gravity by hitting the bottoms of your shoes.
 
An Open Mind said:
Can you stand on enough concentrated light?
Yes, but you need a very powerful source and a very good mirror.

For photon, E=pc where E is the energy, p is momentum and c is speed of light. If you differentiate this by time, you'll get the same relationship between power and force P = Fc. In other words you need 300MW of power per 1N of force (that is if the light is adsorbed or dispersed equally in all directions, half of that if it is reflected fully backwards).
To support a weight of 100Kg on Earth (1KN) you would need a light beam of 150GW.
 
Delta Kilo said:
Yes, but you need a very powerful source and a very good mirror.

For photon, E=pc where E is the energy, p is momentum and c is speed of light. If you differentiate this by time, you'll get the same relationship between power and force P = Fc. In other words you need 300MW of power per 1N of force (that is if the light is adsorbed or dispersed equally in all directions, half of that if it is reflected fully backwards).
To support a weight of 100Kg on Earth (1KN) you would need a light beam of 150GW.

Oh my gosh that's more than I wanted to know! Thanks so much well this thread is done LOL and I love that you spread out the equation, I'm going to write down what you have said and do a lil research on this topic o.o. Thanks again!
 
Google radiation pressure and solar sails.
 
Delta Kilo said:
Yes, but you need a very powerful source and a very good mirror.

Of course the latter is very hard. If the mirror absorbs just a tiny bit of that huge energy source it will melt, warp and deform thus absorbing more and reflecting less and so on and so forth.
 
The way I read the OP, you're standing on the beam as if it were a physical, structural beam; perpendicular to it, in which case the answer would be no.
 
russ_watters said:
The way I read the OP, you're standing on the beam as if it were a physical, structural beam; perpendicular to it, in which case the answer would be no.
Why not? You just need shoes with mirror undersides. Placed at the right angle into the horizontal beam they would produce a vertical force component that would balance the weight of your body.

There would always be a horizontal component away from the source. So you could not remain stationary or walk towards the source. But walking away is no problem.
 
russ_watters said:
The way I read the OP, you're standing on the beam as if it were a physical, structural beam; perpendicular to it, in which case the answer would be no.
Wow, that thought ... didn't ever occur to me ... walking on a rainbow indeed ... :smile: You're right of course
 
  • #10
A.T. said:
russ_watters said:
The way I read the OP, you're standing on the beam as if it were a physical, structural beam; perpendicular to it, in which case the answer would be no.
Why not? You just need shoes with mirror undersides. Placed at the right angle into the horizontal beam they would produce a vertical force component that would balance the weight of your body.

There would always be a horizontal component away from the source. So you could not remain stationary or walk towards the source. But walking away is no problem.

This doesn't really change what Russ said, the OP seems to be asking about support similar to a solid object. Yes we can come up with purely theoretical examples of how you could stand on a laser but it doesn't change the fact that light does not behave like matter in the manner that was originally asked.
 
  • #11
A.T. said:
Why not? You just need shoes with mirror undersides. Placed at the right angle into the horizontal beam they would produce a vertical force component that would balance the weight of your body.
Any angle would do, but in addition to "lift", you are going to get "drag", so a smaller angle is better than high angle.

I am absolutely terrified of the energy densities involved, however. That beam of light would have its own gravitational field. And I mean one you'd be able to measure.
 
  • #12
ryan_m_b said:
the OP seems to be asking about support similar to a solid object..
He asked about walking and standing on a light beam. The answer in vacuum is:

walking : yes (one way, accelerating)
standing stationary: no

In air (ignoring what happens to the air near the beam), you could even walk both ways, or walk in place to remain stationary. But you would need shoes with mirrors and sails.
 
  • #13
A.T. said:
He asked about walking and standing on a light beam. The answer in vacuum is:

walking : yes (one way, accelerating)
standing stationary: no

In air (ignoring what happens to the air near the beam), you could even walk both ways, or walk in place to remain stationary. But you would need shoes with mirrors and sails.

You would need shoes with near perfect mirrors. The small fraction of energy that is not reflected will heat the mirror, melt/warp it and cause more energy to be absorbed rather than reflected. Try standing on a laser like that and you'll quickly find you have no feet left.
 
  • #14
ryan_m_b said:
You would need shoes with near perfect mirrors. The small fraction of energy that is not reflected will heat the mirror, melt/warp it and cause more energy to be absorbed rather than reflected. Try standing on a laser like that and you'll quickly find you have no feet left.

That is not what the OP asked about:
An Open Mind said:
Forget about the heat, the balance you would need and the burn you would get. So your invincible pretty much.
 
  • #15
Interpretations may vary, but I wouldn't consider waterskiing to be standing on the water either.
 

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