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Something worth noting is the only spinning platter HDDs and very few early SSDs actually work the way being described here (old files are actually still there and just waiting to be rewritten)

Modern SSDs use TRIM operations to immediately clear data from blocks as soon as you actually delete it. You'd have to manually disable TRIM, and some SSDs have TRIM instructions as part of their on chip firmware.

And this is why flash storage devices are a nightmare for forensic purposes. With magnetic storage, you can attach a write blocker and know the data on the drive won't change so you can compare hash values and verify nothing changed. Flash memory however will randomly change data so you can't rely on hash values to prove nothing has changed

Just to clear up any confusion, the word memory is often used in confusing ways. Expensive working memory (RAM) is used to do stuff (like a kitchen counter), whereas cheaper storage memory (SSD, HDD) is used to keep stuff (like kitchen cabinets).

Current computers have working memory in the 16GB to 128GB range and storage memory in the hundreds to thousand of gigabytes (known as terabytes)

Phones and tablets (and video game consoles) all have working memory, but the numbers are basically unadvertised (~up to 4 GB). Their storage memory is widely advertised, but is often in the same 16-128GB range as a computer’s working memory, which adds to the confusion.

While technically these are all “memory”, when we speak of a computer’s memory, we usually mean working memory (RAM) — not the one freed up by deleting files. But when we speak of a phone’s memory, we usually mean storage memory (SSD)

My father who was a cop told me that "Cop" stands for Constable on Patrol and comes from a time when cops would walk in pairs around the down town in old timey days.

it's pretty easy for them to limit any server within china "intranet" (call it local internet if you prefer) to not be able to establish any type of communications with any computer or server working from outside of that intranet. when we're talking about china we are talking about a lot more than a simple firewall.

this is not about Reddit.. this is about ways to circumvent the Chinese censorship, and if you believe the Chinese government doesn't scrutiny the Western social networks you are being naive.

Assuming you’re in the US, you can charge whatever, with a few limitations

-You cannot jack up prices on essentials during a state of emergency (no doubling the price of food as people are stocking up for a big hurricane, for example)

-If you have a contract to provide a good/service at a predetermined price, you cannot increase the price for whoever you contracted with while the contract is in effect

-certain goods/services like some utilities and some types of insurance may have a cap on the percentage of profit the company can take or a minimum on the percentage of the cost that goes towards the actual service (under the ACA, 80% of medical insurance premiums must go to paying for medical treatment; electric companies can only take a certain percentage of profit off of infrastructure investments and must otherwise provide electricity at cost).

-Most monopolies are illegal (so you cannot buy all the toothpaste companies and then charge $50 for a tube of toothpaste once your competition is gone)

I think that’s pretty much it. Anything else? Go nuts.

Note that different types of storage handle things slightly differently.

Magnetic storage (HDD, floppies) cannot delete files, it can only overwrite them, so the space will never stand empty.

Flash storage (SSD or a memory stick) will actually delete the file (or parts of the file) at some point (but you won’t know when) and may leave space empty for a while.

Re-writable optical storage (DVD-R) will basically wipe disc contents when you erase it (but is really bad at deleting individual files).

RAM (there are some circumstances where you can delete a file from RAM, such as when using a RAM disk) will retain the file “inaccessibly” until it is either overwritten or the RAM loses power, which causes it to lose all contents.

Note that in every case, “inaccessible” just means harder to access. If the data is there, there are ways of reading it.

I love how this reads like a buffalo complaining about their daily routine at first glance.

The devices that scan the luggage with X-rays are shielded so very little leaks out. They are large metal boxes with a scanner inside and the wall of them absorbs X- rays. The ray is also going in one direction, up or down so not toward where the baggage enters and exits.

The curtains the luggage passes through are rubber with lead in them and are X-ray shields. You have multiple of them per side if I am not mistaken.

So the number of X-Rays that leak out is minimal.

We do not use a small contained unit like that for humans because it would be quite impractical and not a great experience for the patient. We use larger protective boxes that fit humans and are not claustrophobic this is whole rooms

In Sweden there are laws against that, both in criminal law and contract law. There are laws regarding price gouging, laws regarding emergencies (for example, if one is drowning it is not legal to sell them a life vest) and also laws regarding tricking people with “lack of mental capacity” into paying more than a reasonable price for an item. Basically it isn’t, in theory, legally allowed to exploit people.

However, there are no enforced limits regarding interest on loans (used to be 6% until the 1860s). A possible limit is currently being discussed. There are limits for the cost of renting your apartment to someone, however this is rarely brought to court since people firstly don’t know it is possible and also people value a second hand renting contract too high to risk losing their contract, unreasonable costs aside.

Close. Copper buttons were worn on the jacket.

The great firewall basically works in four different ways:

1. Completely blocks access to some platforms/IP (e.g., twitter, WhatsApp, Reddit, known TOR entry nodes, etc.)

2. Completely forbids some sort of traffic (e.g., VPN-like traffic)

3. Intercepts traffic to allowed platforms and applies keyword filtering

4. Huge moderation teams across state supported media platforms

Being able to hide traffic (e.g., special hidden TOR entry nodes whose traffic is designed to blend in with standard HTTP traffic) will allow users to bypass points 1 and 2. The physical transfer of storage as another user mentioned will also work to exfiltrate info.

Using euphemisms (Winnie the Pooh instead of Xi Jinping), non-text media (screenshots, photos and videos), will bypass point 3, at least until the moderator teams catches on.

Point 4 is trickier, but it's basically a race against the clock. Subversive content will be removed, but it might survive long enough to be saved and forwarded somewhere else.

None of this is secret... They are technical limitations (mostly), not really anything that can be done about it.

What I'm not sure is why point 4 is based on accept-by-default (i.e., they could block all publications until moderators reviewed it), but I guess it would put too much strains on the communication, instant messaging would become impossible, for example. So they have to live with it.

There is also the action of a 'destructive delete', where the file is actually overwritten with gibberish. This is done when you want to delete a file without ever being able to restore it. This could be the case when handling confidential information, or in case you plan to retire the PC and hard disk.

Basically, you're telling the system to do the 'overwriting' action immediately.

Yup.

Also, fun fact, computers lie to users all the time. Eg, say you're playing a game and save. The game with very high likelihood will tell you it has saved well before the computer actually did it, and resume playing.

Why? Because people hate waiting, and the computer can actually do the writing to disk while you keep playing without making you wait for everything to be done.

There's many, many such optimizations.

It's like a book. The start of the book has a table of content, that lists all the chapters in the book. If you would want to remove a chapter, you could remove the entry to that chapter from the Table of Contents.

So, effectively, not much is removed, only the entry in the Table of Contents is gone, so you cannot easily find the chapter again. It is still possible, but takes a lot more efffort (skipping through all pages). You could even overwrite the pages of that chapter with something else, adding an entirely different chapter, as long as the chapter is of the same size or smaller than the one you just removed.

Same happens with files on computer storage. There is an index of where all files are located. By removing a file, the entry in the index is removed, effectively making it a lot harder to find that file again, and even allowing other files to be written on the same spot previously filled with that file.

Exactly. The "free" memory is just the available memory, not the empty memory.
In fact memory that has been overwritten can still be recovered.
That's why there is software that "clean" your disk if you want, and it takes a while because basically what it does is just overwrite over and over again the disk until recovery is almost undoable.

Yep, that is what it means.

Oooh that's how they work, cool!

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There are specific programs that allow file "shredding" or "secure deletion", which will overwrite the file location with junk data multiple times. The original file no longer exists and the space is free to use.

O wait, that space is now available to be taken over by new data?

Ok, so why does my computer say that I now have more memory if it's still there? Shouldn't it technically occupy the same amount of space?

Here's my ELI5 version:

Think of your computer's hard drive as incredibly large kitchen table.
And each file on your computer is a piece of paper that gets placed on that table.

The computer keeps track of where each file/paper has been placed so you don't accidentally overwrite something.

When you delete a file, you are not removing the piece of paper. But telling the computer that "this space is now empty".
So the next time you need to save a file, the computer is free to put the new file/paper on top of the old one.