Dial-Up Modem Sound Spectrogram

Pure nostalgia. There was always something satisfying to me when the handshake was over and the bandwidth increased at the end. The tones almost made every connection personal. “You’ve got mail!” was the original Internet adrenaline high. Looking back, it all seems so silly now.

Back from the days of CompuServe and Prodigy, the likes of 14.4 and 28kbs Modems. From a time long before broadband was affordable. Ah the early days.. When connecting to the Internet meant tying up your only phone line for hours. Back then the first multiplayer games like Diablo had a risk of a lurking family member.. Where in the heat of an intense battle, fighting a demon of hell in a dungeon, about to make the winning blow with your friends watching, when someone in your family picks up the phone in another room to make a call and crashes your connection.

Back when the time of day/night you tried to get online really mattered. A famous free shrug from Steve Case for every busy signal when trying to connect to AOL. I remember spending hours trying to configure a com port for that damn modem to get a dial tone. Those were the days.. Kids today with their fancy Google Fiber and WiFi, know nothing of the dread when hearing your modem step down and start over instead of connecting. Or the denial of a busy signal for the 20th time. Don’t even get me started on page load times..

“Spacetime Stretcher,” a new demonstration of gravity

This is one of the best descriptions of gravity I have seen. Here are the main points from the video provided by the author, EdwardCurrent:

1. As a falling object’s path goes increasingly in the space (down) direction, it goes a little bit less in the time direction. Gravity is effectively converting some of its travel through time into travel through space. How much time converts into how much space? It works out to be 186,000 miles of space for every second of time — that’s the speed of light! The equivalence between a little time and a lot of space has a parallel with Einstein’s famous equation E = mc^2, where a little mass is equivalent to a lot of energy — also with the speed of light c as the conversion factor, only squared. It’s amazing how all these physics concepts fit together.

2. An object moving up or down at the speed of light, such as a photon, follows a vertical path on our graph. If we could warp the Spacetime Stretcher as much as we wanted, we could make the time axis curve around and re-intersect with this vertical line. That would be a black hole: Even a photon moving straight up would get “warped back” to the place where it started.

3. Spacetime warping is usually depicted as going into a higher dimension — in this case, bending toward or away from the camera. But such a device would have been much harder to build. You can think of this model as a two-dimensional “projection” or “shadow” of three-dimensional curvature, i.e. the flattening of a flared-out surface that curls away from the plane of the graph.

4. In addition to mechanically calculating trajectories of objects falling on the Earth, Mars, or Moon, the Spacetime Stretcher (at a zoomed-out calibration scale) can also calculate the length-contraction and time-dilation observed with a rocket traveling close to the speed of light.