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If a black hole was next to another black hole and both where equal size what would happen? Would they swallow each other and make a bigger black hole?
  • I’ll echo the other replies that the gravitational waves from black hole mergers have been detected by LIGO. In fact, the 2017 Nobel Prize in physics was awarded to members of this collaboration specifically for this feat.

    We haven’t (yet) seen a pair of black holes collide using light directly, but the gravitational waves have been perfectly consistent with general relativity calculations. Here’s a video from LIGO that shows what one of these simulations looks like, for a simulation that reproduces a detected gravitational wave.

    As an aside, right around the time the LIGO team was awarded the Nobel prize, they detected the collision of a pair of neutron stars. They alerted the astronomy community to the direction they saw the signal from, and within a day there were telescope observations of light from the kilonova that resulted from the collision. Ultimately various sensors recorded optical light, infrared, ultraviolet, gamma rays, and radio waves being emitted from the explosion. The hope is that someday we’ll get lucky enough to see similar photon signatures from a black hole merger!

  • Can a Four-Year Degree in Any Hard Science Realistically Get You a Good Job?
  • For physics specifically, a bachelor’s degree probably won’t be enough to get a job in physics.

    You might be able to get a job as a technician in a lab, but they typically will look for people with a master’s degree for those roles. With just a bachelor’s , you’d need to get your foot in the door by already having some relevant experience, which is a possibility if you get some research experience in college and pivot that into an internship or something. But it would definitely require effort and luck.

  • When you see 'heat rising', what are you actually seeing?
  • You’ve gotten some good answers explaining that heat changes the density, and therefore the index of refraction of air.

    Fun fact: Schlieren Imaging allows one to photograph shockwaves by relying on the same effect. As a shockwave travels through air, it creates a region of high density, which can be imaged with this technique.

  • If space didn't expand/accelerate, would photons keep zipping along forever in the same wavelength in which they were emitted?
  • in the photon's frame of reference

    There are no valid inertial frames for an object moving at the speed of light. The idea that “a photon doesn’t experience time” is a common, but misleadingly incorrect statement, since we can’t define a reference frame for it. Sometimes this misconception can be useful for conveying some qualitative ideas (photons don’t decay), but often it leads to contradictions like your question about Hawking Radiation for black holes.

  • If space didn't expand/accelerate, would photons keep zipping along forever in the same wavelength in which they were emitted?
  • Yes, the wavelength of photons will be preserved if they travel through non-expanding space. If the photon is emitted by a source that’s in motion with respect to a detector, there could still be redshift or blueshift from the relativistic Doppler effect. This would only depend on the relative velocity between the emitter and observer, and not on the distance the photon traveled between them.

  • Beyond the established symmetries of physics - Charge, Spin, Color, Time, etc. - is there any such thing as symmetry of Information?
  • This falls a bit outside my wheelhouse but I believe the answer is no. The established symmetries in particle physics are all associated with the quantum mechanical state of a particle (charge, parity, etc) and to my knowledge there isn’t an “information” quantum number.

    The closest you might get to this is quantum information theory, where information is encoded in other physical characteristics (spin, parity, energy, etc). In this sense information is more of an emergent phenomenon than a fundamental property.

  • [Physics] Does gravity have 'elasticity'? If a solid sun-sized object zooms across space at the speed of light, then abruptly stops, does it take gravity some time to 'settle' around it?
  • Hah tell me about it. The 2017 neutron star merger happened while I was writing a proposal for an experiment where the physics was sort of related. So of course I completely reframed the proposal around that event, and it got funded! And that was just a few years ago, right?

    Man I really need to publish the results of that project…

  • Is there a temperature so hot that relativistic effects are noticeable?
  • Certainly! You can see discrete emission lines from the ionized air molecules, which only occurs because of quantum physics. I realize that’s not what you’re asking though.

    I did a quick calculation and for a plasma torch (~27000 Kelvin) and assuming air molecules, the average velocity of the plasma ions would only be like 6000 m/s. That’s 0.001% the speed of light, so you aren’t going to see any relativistic effects.

  • [Physics] Does gravity have 'elasticity'? If a solid sun-sized object zooms across space at the speed of light, then abruptly stops, does it take gravity some time to 'settle' around it?
  • First a caveat: An object with mass can’t move at the speed of light, but it could move at speeds arbitrarily close to that.

    The most successful model of gravity isGeneral Relativity, which treats gravity as a curvature of 4-dimensional space time. Gravity’s influence travels at the speed of light. There’s a classic thought experiment that sort of answers your question: what would happen if the sun was teleported away? The answer is the earth would continue to orbit around the spot the sun was for 8 minutes, and we would continue to see sunlight for that same amount of time since that’s how long it takes light to travel that distance. Then after 8 minutes the sun would disappear and the first “lack of gravity” would reach us, and things would be bad for earth :(

    The fact that gravity travels at the speed of light actually leads to an interesting phenomenon: Gravitational waves If a massive object rapidly accelerates (or decelerates), for example a star sized mass moving quickly and then coming to an abrupt stop, it will emit a ripple in space time called a gravitational wave that will travel outward at the speed of light.

    It was big news about a decade ago when gravitational waves were first detected by LIGO, a series of large interferometers that look for expansion/contraction in spacetime. Their first detection was the collision of 2 black holes; as the black holes spiral around each other and eventually merge, they emit oscillating waves with increasing frequency. They made a cool video showing how the frequency increases by converting it to sound.

    Since then LIGO and VIRGO (similar European collaboration) have detected multiple gravitational waves from the collision of black holes and neutron stars. So not only are gravitational waves a neat validation of general relativity, they’re actually being used to do astronomy.

  • This is probably a dumb question, but if we eliminate the hydrophobia caused by rabies, would it increase the survival rate of active rabies?
  • The Milwaukee Protocol is a treatment plan that is essentially a more advanced version of what you’re asking. The patient is put in a medically induced coma and then given antivirals and IV fluids, which avoids the issue of hydrophobia.

    It got a lot of press because one person survived on it (a big deal given that rabies is a death sentence once symptoms appear) but this success hasn’t been reproduced with other patients. A paper on the protocol has a remarkably blunt title: Critical Appraisal of the Milwaukee Protocol for Rabies: This Failed Approach Should Be Abandoned.

  • [Solved] Trees supposedly take 30 years *before* they absorb CO₂. Why?
  • Hi there! Can you please remove the word “retarded” in your first sentence? This word is now generally considered a slur, which runs afoul of rule 6 “Use appropriate language and tone. Communicate using suitable language and maintain a professional and respectful tone.”

  • Can sufficiently energetic EM waves of a specific frequency affect weaker EM waves of a different frequency?
  • I second the other poster’s suggestion to look into nonlinear optics. A really common application is frequency doubling, also known as second harmonic generation, which doubles the energy of the photons. So an 800 nm laser (red) can be converted to 400 nm (green) with this method.

    The National Ignition Facility (NIF) actually uses frequency tripling of the laser pulses right before they enter the target chamber. That’s pretty wild, I had intended to look up NIF to give a high profile example of second harmonic generation, I hadn’t realized they were actually doing third harmonics.

    Another optics-based phenomenon that I think maybe strays too far from the intent of your initial question, but is too cool not to share, is laser Wakefield acceleration. A very high power laser pulse will push electrons out of its path in plasma or materials via the ponderomotive force. This charge separation creates electric field gradients on the order of billions of volts per centimeter, which can accelerate electrons or other charged particles to relativistic energies. So you can start with a green laser pulse and wind up producing gamma-ray beams, either by slamming the electrons into a stopping material or by Compton scattering other low energy photons off the relativistic electrons.

  • Does Higgs exist in nature or is it merely artificially synthesized particle?
  • But in order to do that photon actually needs to be created and travel from one particle to another.

    The electromagnetic force is mediated by virtual photons. These don’t exist as free particles, such as a photon emitted by a light source, but only as an intermediate particle. Because they’re only intermediate states, virtual photons can have non-physical energies (so long as they’re within the uncertainty principle), resulting in some having an effective mass. Suffice it to say virtual photons are quite distinct from real ones! Technically, I believe you could have some of the basic features of the em force (namely attraction/repulsion by 2 point charges) with just virtual photons. Things get tricky once charges begin accelerating though, as this leads to the emission of real photons.

    If Higgs works in a similar way also being a boson

    The short answer is, it doesn’t. The Higgs Field gives mass to fundamental particles. Existing in that field causes certain particles to have mass due to their coupling to the field. The W and Z weak gauge bosons gain mass through electroweak symmetry breaking, quarks and leptons gain mass through a different coupling. I realize this is a very unsatisfying answer as to “how” the Higgs field creates mass, but the mechanism involves some complex math (group theory and non-abelian gauge theory), so it kind of defies a simpler explanation. Regardless, it’s through interactions with the Higgs field (which can exist without any Higgs bosons around) that fundamental particles gain mass. The search for the Higgs boson was just to confirm the existence of the field, because while the field can exist without Higgs bosons present it must be possible to excite it sufficiently to create them.

    Going back to your original question: these particles have almost certainly been created “naturally” in high energy collisions between particles and matter. Nature can achieve much higher energies than our particle accelerators. The highest energy particle ever observed was a cosmic ray. However, Higgs bosons are extremely short lived, with a lifetime of 10^-22 seconds. So whenever they’re created, they don’t stick around for a meaningful amount of time.

  • Is there an insect that can devour plastic, breaking it down to less harmful components?
  • Im dealing with all rule breaking behavior. The unsourced comments have now been removed as the user is unable to provide a source to backup their claim. The comments that break civility rules, including this one, are also being removed.

    Please report rule 9 violations so that we can act on them.

  • Is there an insect that can devour plastic, breaking it down to less harmful components?
  • The source provided by another user gives a definitive counter argument.

    From the article: “ The wheat kernel contains 8%–15% of protein, from which 10%–15% is albumin/globulin and 85%–90% is gluten (Fig. 1).1 Gluten is a complex mixture of hundreds of related but distinct proteins, mainly gliadin and glutenin. Different wheat varieties vary in protein content and in the composition and distribution of gluten proteins.”

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