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### Accelerating Expansion of Universe - Why Not Caused by Radiation?

As I understand it, dark matter and dark energy are used as an 'explanation' for how universe expansion is accelerating; because without it gravity would be expected to cause a long term shrinking. ...
• 181
127 views

### How big is light pressure as a fraction of light energy?

Light hitting a surface impart a force on the surface, often called "radiation pressure". My question is, given a perfectly reflective surface, if light hits it at 90° to return in the ...
• 195
1 vote
51 views

### How can I relate the temperature and pressure at the core of a star? [closed]

There are many ways to estimate the temperature of the core of a star, one of which is by radiation pressure and the gravitational force of the star on itself. I am unable to relate both of them ...
1 vote
20 views

### Optical Tweezers in a Vacuum | Oscillation

In the context of optical tweezers, if used in a vacuum and a particle starts off slightly to the right from the center of a beam, would the particle eventually become perfectly centered or would it ...
• 11
1 vote
71 views

### Is the force constraining the maximal speed-of-matter the background photonic pressure?

To start: Not a physicist, just a curious idiot. Forgive my lack of understanding if there is something fundamental I miss here. I've seen similar questions to mine, and answers relate specifically to ...
• 11
61 views

### Constant velocity motion in a radiation bath

A perfect conducting plate is moving in an infinitely large space, which is in thermal equilibrium with the plate at absolute temperature $T$. Since the space is filled with black-body radiation, if ...
24 views

### Is this paper's finding on radiation-pressure displaced Lagrange point $L_1$ incorrect?

I'm referring to the paper An L1 positioned dust cloud as an effective method of space-based geo-engineering which can be found here: http://strathprints.strath.ac.uk/27439/. I am about to try writing ...
237 views

I've been told that the radiation pressure of light can be understood(?) by considering a charged particle as a damped driven harmonic oscillator where the forcing term is the electromagnetic field, ...
1 vote
92 views

### Does the Parker Solar Probe experience radiation pressure being so close to the sun?

Since the Parker Solar Probe does close fly-bys around the sun, does it experience any significant radiation pressure from photons emitted by the sun? Is this push, significant enough to require ...
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51 views

### Radiation pressure at a surface which is perfectly refracting

Radiation pressure at perfectly reflecting surface = 2I/c Radiation pressure at perfectly absorbing surface = I/c What will be the radiation pressure at a perfectly refracting surface? Will it be ...
95 views

### Can light radiation pressure change its own path

Well i have seen that light creates radiation pressure Can two light waves coming from two different direction change each others path?
78 views

### How are solar sails maneuvered by sunlight? Are they pushed or pulled?

On 20 May, 2010, Japan launched IKAROS probe with primary propulsion by a solar sail. If the radiation pressure, that helps the sail to move, comes from the sun, then shouldn't it be pushed away from ...
• 35
49 views

### How will the Starshot swarm accelerate perfectly?

I was reading about the Breakthrough Initiative Starshot and I a question came to mind. From my understanding, the "mothership" will focus powerful lasers on each of the tiny ships, accelerating them ...
• 197
10k views

### Can an atom orbit the Sun?

Is it possible for a molecule or atom to orbit a star (e.g. the Sun)? Or is there always too much outward force imparted by solar radiation compared to the inward force of gravitational attraction?
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### Euler-Bernoulli equation for a cantilever strained by a force

I'm trying to model an experiment where a cantilever, fixed at one end, is oscillating under an applied force at the free end. Specifically, I'm focusing a laser on a rectangular cantilever and ...
1 vote
67 views

### Can I close my door with a torch? [duplicate]

Photon pressure is definitely one of the most amazing phenomenon that I have heard in a while. Some examples: The pressure from the photons emitted by the Sun can perturb the motion of artificial ...
• 1,988
305 views

### why do hypergiants shed mass before death?

I'm reading on this website here and will be using lots of quotes from it. Hypergiant Star Seen Shedding Mass Ahead Of Explosive Death As Supernova Astronomers using a telescope in Chile have ...
• 835
931 views

### Can we use radiation pressure to push/levitate a human?

I want to know, at least in theory, are there any safe em wavelength that could affect human body as net force and do no harm? To put it bluntly I want to know is it possible for levitate a human on ...
• 898
56 views

### Angular distribution of scattered photons in laser cooling

I currently prepare for a magneto-optical trap undergrad lab. Radiation pressure comes from the photon's momentum, that is clear. The emission of the photon (some time later) will give another recoil ...
• 8,439
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### Radiation pressure applied to different color surfaces

Does the value of radiation pressure exerted by photons from sunlight vary when applied to surfaces of a different color? More specifically, ranging from pitch black to white surfaces. Also, is ...
1 vote
878 views

I was watching a video on Youtube (Vsauce, great channel, check them out), and they were talking about how much a shadow weighs, and he was talking about sails that were pushed by light. He said an ...