balios

@ilza: I'll tear up my engineering degree and tell Lawrence Krauss he's a quack. Thank you for setting us straight.

"does rocket just outside EH see same thing as Earth observer sees 1 month later"

The Earth will appear blueshifted (higher frequency) to the rocket. The laser coming from from the rocket will appear redshifted (lower frequency). The degree to which will depend on the actual distance to the event horizon. There will be time dilatation, so 1 month for the rocket is not 1 month for Earth (longer for Earth).

"So, in your educated opinion, the situation of “a moving black hole” differs from an object falling to a stationary black hole? Yeah, right!"

At time T = 0, black + object at distance X with no relative motion. The object will vanish at time T1.

At time T=0, same black hole + object at distance X, but with a relative motion towards each other. The object will vanish at time T2.

T2 < T1.

Consider objects approaching the cosmic horizon (which is identical to objects approaching any horizon):

"Objects therefore appear exponentially redshifted as they approach the horizon. Finally, their apparent brightness declines exponentially, so that the distance of the objects inferred by an observer increases exponentially. While it strictly takes an infinite amount of time for the observer to completely lose causal contact with these receding objects, distant stars, galaxies, and all radiation backgrounds from the Big Bang will effectively “blink” out of existence in a finite time – as their signals redshift, the time scale for detecting these signals becomes comparable to the age of the universe"

Life, The Universe, and Nothing: Life and Death in an Ever-Expanding Universe

Lawrence M. Krauss and Glenn D. Starkman

arXiv:astro-ph/9902189v1

<" THERE IS NO NOTION OF A MOVING OBJECT! Speed is a RELATIVE notion">

Your statement is an exercise in gibberish as are your other statements. Speed is the magnitude of relative motion. To say that motion doesn't exist is to say that objects can't have relative speed. A moving black hole is moving relative to an observer/object, the magnitude of which affects the equations of motion.

An expanding black hole is no different from a moving black hole: it simply changes how fast an infalling object approaches the event horizon. If a lot of matter is falling into a black hole at once, that simply means the horizon is expanding and time dilation and photon energy approaches zero faster for such matter.

Also keep in mind that high energy particle jets at the poles of the black hole are necessarily NOT occurring in regions where time dilation approaches zero. These particles are accelerated to 99% of the speed of light, but this is only a 7x time dilation factor. The majority of particles never receive enough energy to escape or are on a trajectory into the black hole.

The time dilation of these particles increases very rapidly (7x -> 700 -> 7 billion -> 7 billion billion billion times, etc). These infalling particles become more and more "like" the event horizon they are approaching until the are indistinguishable from it (to an outside observer).

The math says that as an object approaches the event horizon, the observed passage of time to an outside observer approaches zero. It will never reach zero but the distance will decrease exponentially (ie. the object will eventually "freeze" to outside viewers).

BUT, this also means the redshift approaches infinity (most people ignore this, leading to the confusion). Therefore the energy of any photon released when the object appears "frozen in time" exponentially approach zero to the outside observer. So no matter the energy level of the photon released, it will be finite and therefore approach zero to an outside observer (but not to the infalling object, photon energy depends on frame of reference).

Eventually even the most sensitive equipment will not be able to detect that photon and will be indistinguishable from the Hawkings Radiation, ie. the object is now indistinguishable from the back hole to an outside observer (ie. it is now part of the black hole).

It will take forever for you to "see" the matter cross the event horizon. From our point of view, rather than a "frozen image", the infalling matter becomes more and more red shifted and dimmer. This continues until the matter is essentially invisible because it will take an infinite amount of time to get that last infinitely red shifted photon from the matter crossing the horizon.

So take a 1 solar mass black hole (2.9 km radius black hole) and throw a 1 solar mass at it. Assuming all the matter goes into the black hole: the matter will be shredded, become more red shifted and dimmer until essentially undetectable, and the black hole will grow to 2 solar masses (5.9 km radius).

We will never "see" the matter fall in just like we can't "see" the event horizon. The "unseeable" region of space will grow to 5.9 km in radius.

Mars is fundamentally uninhabitable. We could fill Earth's oceans with garbage until we can walk on it, then detonate every nuclear warhead on Earth, then get hit with a dino-killer asteroid, and the resulting apocalyptic wasteland would still be a paradise for life compared to Mars. So I'm not sure how we'll "trash" Mars when its already trash.

There are fields of photography producing images for business purposes rather than art: website graphics, advertising, online/offline catalogs, product manuals, etc.

In that case It's important to understand and deliver what your client/employer wants. A business has no interest in the "true art of photography". There's no value in a photo being unaltered for sake of photography.

In some cases altered photographs will violate laws or create legal liabilities. In that case you need to understand the nuisances on what you can and can't deliver.

Ultimately, we can argue all day about the semantics of whether the altered surfer photo (above) is still a "photograph". But that's a meaningless discussion for a business that's creating a billboard... So you do your work, satisfy the client, move on to the next job and leave the semantics for the
forums.

I don't think Amazon cares. Amazon Basics and Peak Design products are aimed at different customers.

The average Amazon Basics customer is judging whether to buy the $10 no-name bargain sling bag or the $25 backed-by-Amazon bargain sling bag.

Peak Design is selling a more premium product that comes with a story on why purchasing their product makes you a better person (as told in the video). That's a different clientele from the Amazon bag, The existence of the Amazon "Basics" product actually helps Peak Design market its product as "premium". Its why the video was created.

The price keeps rising for the Amazon bag (was $27 a few minutes ago, now $30 as I write this), which according to the Amazon algorithm means its selling well (possibly thanks to this article). It is also interesting how the negative reviews on Amazon are from Peak Design employees (confirmed via Linkedin).... lol.

It says "cruelty-free, environmental-friendly, and non-toxic synthetic leather". So its not real leather (veg or chrome tanned) and likely not a petroleum-based synthetic leather. It could be something like Pinatex (a cellulose-based synthetic leather).

I would laugh if one person enters. The OP will be out $65....

@grahamho, "This criticism of a woman photographer"

You're the only one bringing gender into the discussion.

"You tell me why some readers of this article are criticising the technique "

At 6:05 in the video you can see the camera sway back and forth. I picked up on that only because *I've* had to work through similar issues when using a monopod. Monopod technique is of interest to me, far more of interest than the performance of a lens I'll never own.

With F1.8, daylight, and the giant reflector that is snow, the swaying should cause no issue. But reduce the lighting and that swaying can effect the focus/sharpness. A monopod is not a tripod, but when braced against your eye, your legs and the monopod effectively creates a tripod.

Expense/profit has nothing to do with fraud. Most "contests" that require an entry fee (eg, lottery tickets, casinos) are bad value to the contestants and result in high profits for the operator. That doesn't make it fraud. Fraud is using deceit to obtain something of value.

If the contestants willingly gave the $20 per entry free, the photos were all equally judged, and the promised prizes were given out, then there is no fraud. Perhaps fraud took place during the judging, but there isn't enough info given to say that occurred.

I agree that these types of awards are suspect and should not be publicized. But I suspect that most contestants knew the award was a bad financial investment. IMHO they probably enter many contests like this for that small chance to call themselves and "award winning" photographer.

I picked up on that as well. But as she said, the lens is much larger than what she normally uses (85mm?). So I suspect she's simply adapting her normal technique to an atypical situation. If you throw a 7 lb lens at somebody and film them use it for the first time, don't expect perfect form.

Now we only need a Verneer painting of DPR's studio test scene so we can add him to the comparison tool. That way I can compare him against my 5Div. IMHO, Canon has the edge in sharpness.

Previously, multiple prototypes would be developed during product development to test various ideas for feasibility. To use your example of scientific theory: the "theory" was developed piecemeal through multiple experiments.

Now, complete prototypes will be manufactured at the end of the development cycle to confirm the validity of the simulations. In other words, complete theories will be tested. So Mr. Feynman is still being respected.

The prior method is slow and costly. You're investing in materials, tooling, and manufacture that may be rendered obsolete by future testing. Take the desired body from one tested prototype, the desired sensor from another, and the result could be unexpected overheating.... oops, its too late in the development cycle and we're over budget on tooling so I guess we just limit the record times.

What gives it away is the sensor plane marking next to the "mushroom". Most cameras will have that symbol on the top of the camera. The knob makes it easier to utilize that location for measurement.