Observer Definition and 331 Threads

When we say that the the velocity of light, c, is independent of the velocity of emitter or the observer, does it mean that .. if we are in an spaceship and measure c with Fizeau arrangement we will obtain the same result, no matter the velocity of the spaceship nor the velocity of the...

Homework Statement You're flying in an aircraft at 46 m/s. An eagle flies directly towards you at 11 m/s. Speeds are relative to ground. The eagle emits a cry at 3400 Hz, and the speed of sound is 330 m/s. What frequency do you hear? Homework Equations f_o = f_s\left(...

In this example, which I found via Wikipedia on Delayed Choice, http://www.bottomlayer.com/bottom/basic_delayed_choice.htm" it makes the "observer" special, i.e. it's the observer who "chooses" whether the photon goes through one slit or the other, or through both as a wave, or more...

Alright, I've been doing a lot of reading and talking with my professors at college, and I just can't seem to wrap my head around the observer effect. Basically, Schrödinger's cat. I've heard a lot of analogies to compare it to, but I'm still baffled by it. I've heard "If a tree falls in...

It is my understanding that if an observer accelerates he must rotate in space-time. But then why is that factor generally omitted in the calculations related to accelerations?

:smile: Hi all, In quantum physics (i.e. the double slit experiment with electron), why does mere act of observing the electron affect the fact of whether its a wave or particle? Please answer in laymens terms if possible as i am no physicist! Thanks in advance :smile:

In Special Relativity, If an inertial photon emitter, A, emits photons every second and an observer, B (moving away from A at a constant velocity v), intercepts these photons and instantaneously reflects them back to A then we would expect to see the Doppler redshift effect. My question I...

I have a problem that I can not understand what I am doing wrong. A rocket moves at 1.0*18^6 m/s. Inside is an E Field (coming out of the page of the book) that is 2.0*10^6 V/m. There is also a B Field in the rocket pointing up that is -1.0 T. What is the E Field observed by someone on Earth...

A muon is created 3km above the Earth's surface heading downward at a speed of 0.98c. It is able to survive 2.2\mu s in its own frame before it decays. (1) The muon travels a distance of 647m before it decays in its frame d = vt = (0.98\times 3\times 10^8m/s)(2.2\times 10^{-6}s) = 647m...

Hi, i am confused by the following question: When an observer is going towards the horizon of a BH from outside, he finds the light from far away so blue shifted that the far future of the far away world presents in front of him. Does that mean when he is crossing the horizon, he has seen...

Let says there's a starting point A. Two observer, B and C travel from point A in opposite direction with 90%c. How can we calculate the speed of observer C as observed by observer B?

I recall that an object's mass increases as the the object travels faster through space. Question: Imagine observer A is stationary, and observer B & an object move near light speed. When observer A and B measure the mass of the object, do they measure diffenrent masses?

:confused: I am sooo intrigued. The speed of light is independent to the speed of the observer. Why? I don't understand and is it the speed of light only that is independent to the speed of the observer? What makes it so special?

Since in relativity everything is relative to a frame, doesn't that mean that in relativity theory (RT), all measurements are observer-dependent? Doesn't RT historically precede quantum theory (QT) in that respect? I am asking this because it seems to me that there is a general presumption "out...

Before I begin I feel that I should state that I have only a passing amount of knowledge on the subject so if I've got something wrong let me know. My current understanding of QM is that certain atomic attributes are created through observation of these attributes. This seems to suggest that...

Stupid Question: SR says that c is constant in which ever I-FRAME its in right? now does that include an observer looking into the system? that they would also measure c? or would they measure c+vFrame? Also Does this have anything to do with the "index of refraction" between mediums...

What should I say to people who claim that QM supports the view that the universe couldn't exist without humans or some kind of "observer"? Really?? I see where this comes from, but what is the truth? I'm not talking about getting into an ontological argument- just what QM really has to say on...

Some investigators, including Einstein and Planck, have found expressions relating temperature and the velocity of an observer . ¿ How is it possible if temperature is a thermodynamic property independent of trajectory and time?

I'm wondering if someone could tell me what would be the result of the following thought experiment, to help answer a simple question I have about the Heisenberg Uncertainty Principle: (I am just an educated layman trying to figure it all out- hopefully my thought experiment isn't complete...

Hi, I recenlty had a friend whose interested in QM email me an article: http://www.space.com/searchforlife/quantum_astronomy_041111.html , asking for more explanation. This is the explanation I sent in a sleep-deprived state of mind (in fact, I'm still in said mind state as I post this now :) )...

Is it true that Einstein believed that for reality to exist, an observer must be present? If so, what is the current theory on the existence of an observer, early on in the development of space-time?

what defines an observer for reality to exist externally? (refer to Einstein) personally i am not convinced an observer must have conciousness (i am not sure about how Einstein defined it). what is consciousness anyway? i mean i believe i am consciouss, but it seems to me that there are...

Does quantum mechanics allow an observer free choice of measurement?

Using Speical relativity, of course If two trains leave a station on the same track. An observer missed both these trains and is standing close to the track sees the westbound train recede at 0.6c and sees the eastbound train recede at 0.8c. There is a ticket collector on the westbound train...

This is just to be a bit of fun but also to express whether or not you think that the quantum physicist should be labelled an observer or a participant? And also why or why not? I mean I think this is such a great subject, but it may be really boring to some people! (sorry about the spelling...

I wonder if each path in a Feynmen path integral might represent another path from an observer in a different frame of reference. Perhaps if another FOR is accelerating, it may appear as if the path we might consider looks distorted from that other FOR. If so, then QM is accounting for every...

What follows is my attempt to make a comprehensive list of properties that observers and observation exhibit. Please add your own, or critique those already there. Observer Characteristics 1. An observer increases its accessible spectrum over time 2. An observer increases memory...

You are on a salt flat, away from the city lights, no moon and it is cloudy. It is pitch black, you can't see a thing. It is a salt flat so there is nothing for miles. You shine a torch so the beam hits a hundred meters in front of you onto the ground. If the light is traveling away from you at...

Since all motion is relative to an inertial frame of reference, is a bodies kenetic energy only relevant when the observer is the intertial frame of reference? (i.e. would the kinetic energy be different for another observer and if so does this violate any of the principles of energy...

"Observer Dependant" vs "Invariant" The point I want to make in this thread is on something with is rather subtle. Define the quantity, m, as the quantity such that, in an inertial frame, mv is conserved. Call this quantity "mass" (some call this "relativistic mass") For tardyon's...

Considering that certain areas in physics today rely on an observer, such as when considering the collaspse of a wavefunction, I think that we need a good physical definition of an observation. So what is an observation? I like to think of it as a change in configuration or state. Think...