What is Blueshift: Definition and 26 Discussions

A blueshift is any decrease in wavelength (increase in energy), with a corresponding increase in frequency, of an electromagnetic wave; the opposite effect is referred to as redshift. In visible light, this shifts the color from the red end of the spectrum to the blue end.

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  1. T

    I Is Gravitational Red-Blue Shift Dismissed in Cosmic Observations?

    Why is gravitational red blue shift ruled out as a cause of what we see in stars and galaxy's and such?
  2. S

    I Photons being blueshifted when crossing evolving voids?

    I was reading this paper (https://academic.oup.com/mnras/article/288/2/387/960778) where they analysed how CMB radiation is affected by evolving voids in an expanding spacetime (particularly through the Rees-Sciama effect and the integrated Sachs-Wolfe effect). This effect predicts that photons...
  3. S

    I Dark energy and the kinematic Sunyaev-Zeldovich effect?

    I was reading this interesting article about possible effects of dark energy in the formation of large-scale structures which should have an impact on the Sunyaev-Zeldovich effect ("Dark energy imprints on the kinematic Sunyaev-Zel'dovich signal" (https://arxiv.org/abs/1309.1163))There, the...
  4. sol47739

    I Is the light from Andromeda truly blue shifted?

    I asked a similar question on Quora not that long...
  5. M

    Measurement of speed using redshift or blueshift

    The solution on my textbook is 13000m/s toward Earth as the light is blue-shifted I'm able to calculate the magnitude of velocity (13000m/s), but i don't understand why thus is blue-shifted? Since in the lab, the light's wavelength observed is slightly higher than light from Ursa Majoris. So my...
  6. G

    I Falling into a Black Hole: Blueshift Questions Explored

    I am under the impression that an outside observer would see things redshifted as the person they are observing approaches the event horizon. So, it seems reasonable that someone from inside the black hole would see incoming light blueshifted. Is this inaccurate? Why or why not? If it is...
  7. Revolucien

    B Exploring the Effects of Black Hole Gravity: Blueshift

    Does the extreme gravity from a black hole cause a blueshift in light approaching the event horizon? sorry for the newb question
  8. N

    I Does a blueshift change the energy of a photon?

    The energy of a photon depends on its wavelength, so theoretically when it is blueshifted it should have more energy right? Then what if a spaceship with a solar panel on the front is traveling towards the sun at relativistic speeds. An incoming photon undergoes a blueshift from the observer on...
  9. P

    I How Can We Measure Redshift Using the Spectrum of a Star?

    As far as I know, when we use the spectrum of a star, we see where the absorption lines are and using this, we can detect the elements that are present in the star. We also measure whether those absorption lines are supposed to be for a particular element. But why is it not possible that the...
  10. G

    Solar Sail/ Mirror Redshift & Blueshift

    Hi all, I was hoping you could help me out with this one. Im trying to calculate the redshift or blueshift of a photon that strikes a mirror and reflects. I know E=pc, and that 2p is the momentum transfer. I also know that kinetic energy is 2p/M (of the mirror). However, this says that...
  11. E

    Signal time in Twin Paradox: Fast clocks? Redshift/blueshift

    NOTE: This is NOT a homework problem. I created this one myself based on some problems I have seen, with specific numbers used to make calculation clean and easy. Tl/dr version: in a round trip to a star, will the "moving clock" run slower on the way there but faster on the way back due to the...
  12. Q

    Redshift and blueshift in relativistic doppler effect

    I'm looking for an intuitive explanation for the redshift and blueshift phenonema that occurs when a light ray is emitted transversely. According to wikipedia: Assuming the objects are not accelerated, light emitted when the objects are closest together will be received some time later...
  13. S

    Blueshift at event horizon in rest and accelerated frames

    Basic question I'm sure, but here goes; If the following is correct; An object may be considered to be 'at rest' when there are no inertial forces acting upon it (ie; it is not accelerating). A satellite is at rest because it is in freefall. A person standing still on the Earth's...
  14. L

    Redshift / blueshift of light in a gravity well

    I appreciate that as light approaches (say) a star, the light is blueshifted by gravity, and that as it leaves the area of the star, the light is redshifted as it climbs out of the gravity well. However, given that spacecraft execute gravity assist manoeuvres to increase / reduce speed, does...
  15. M

    Redshift and blueshift in expanding universe

    At first, people thought the universe was stationary. This seemed logical, why would any object tend to move in one direction or the other if there was the same amount of mass in all directions? Then they noticed the redshift of distant galaxies and concluded that the universe must be expanding...
  16. T

    Do Falling Observers Experience Blueshift Inside a Black Hole?

    If you could safely stand inside a black hole about the size of a small room, filled it with smoke, and shined a laser - would you see the light not only bend towards the warping gravitational field but also blueshift? My previous post was removed so if you responded I didn't get it. I guess...
  17. A

    Newbish questions (shape of the observable universe, blueshift, etc.)

    Hello! I've juggled these questions around my mind for a few days now and so far haven't been able to google any useful information: 1. What is the approximate 3D shape of the observable universe? The Wikipedia article on this subject talks about weird stuff, like a "flat universe" and...
  18. K

    Blue Shift & Red Shift: Explaining the Universe

    I have a question.. So far, from what I've browsed on the forums, I haven't found an answer to it, and I figured this would be the best place for it. I'm aware of the balloon analogy, but I have a question regarding blueshifts and redshifts. If you take the balloon analogy, everything in the...
  19. L

    Cosmic background radiation - redshift, blueshift, anisotropies

    I've been trying to find out more about cosmic background radiation, but I am unable to find any information on the variations in the measured cosmic background radiation. I'm talking about these WMAP images. Most of the images you'll find on Internet are the versions after being corrected...
  20. S

    What's Wrong with Big Clock Moving at 0.1C?

    Big clock is coming towards us at 0.1C. Seconds pointing hand is, say, green. From time it moves from 0 to 1 sec it will emmit 6 x 10 e14 wave crests. We will receive same number of crests in 0.9 sec, so it will look to us like that seconds pointing hand is moving every 0.9 sec, and being a...
  21. N

    Gravitational blueshift and a Moving Mass

    Gravitational blueshift corresponds to the difference between the underlying clock rates at the emitter and at the observer. Which means that the wavelength at the instant of emission is already longer as measured by the observer's clock than the same emission as measured by the emitter's clock...
  22. N

    Gravitational Time Dilation & Blueshift

    Consider a theoretical nonrotating solid massive ball of constant density. A shaft is drilled from a point on the surface down to the center. A light source on the surface is aimed down the shaft. Observers at each end of the shaft carry clocks which initially were synchronized before...
  23. G

    Blueshift + Classical Physics = Golden Ratio

    I was doing calculations to see how far classical physics would take us in terms of the speed of an object never exceeding the speed of light in a reference frame. Here was the scenario I set up: http://la.gg/upl/light.jpg So, if we want to find the time it takes the light to get from (A)...
  24. L

    Redshift & Blueshift: Is There a Consensus?

    Since we have been taken readings of redshift, blueshift for sometime now, is there a consensus on a percentage of each?
  25. Curious3141

    Proving relativistic blueshift with Lorentz transforms only

    Dear esteemed physicists :) I've been trying to satisfy my own curiosity by proving relativistic Doppler using only Lorentz transforms between two inertial frames, one holding a source, the other the receiver. I've managed to derive the correct expression \frac{\nu}{\nu_0} =...
  26. S

    Discover the Controversial Gravitational Blueshift Phenomenon

    It's known and experimented when you shoot a light beam upward from Erath surface to a light detector at higher altitude, the light detector will detect a redshift. This is called gravitational redshift. Both my friend and I agreed from how this was deduced, we shall see a blueshift when the...